The most powerful and largest particle accelerator host CERN is up to experiments to look for particles that are associated with the mysterious dark matter. The dark matter is believed to make up about 27% of the universe according to the European physics lab.
The dark matter is a mysterious substance which is perceived through its gravitational pull on other objects. According to the scientists associated to the study of space science, the so-called ordinary matter – which includes stars, gases, dust, planets and everything on them – accounts for only five percent of the universe. “Some of these sought-after particles are associated with dark matter,” a statement from CERN said.
Using observations from NASA’s Hubble Space Telescope and Chandra X-ray Observatory, astronomers have found that dark matter does not slow down when colliding with itself, meaning it interacts with itself less than previously thought. Researchers say this finding narrows down the options for what this mysterious substance might be. Dark matter is an invisible matter that makes up most of the mass of the universe. Because dark matter does not reflect, absorb or emit light, it can only be traced indirectly by, such as by measuring how it warps space through gravitational lensing, during which the light from a distant source is magnified and distorted by the gravity of dark matter. (Credit: NASA Goddard)
On Tuesday, the European Organization for Nuclear Research (CERN) announced that it has approved the experiment designed to look for light and weakly interacting particles at the Large Hadron Collider (LHC) — a giant lab in a 27-kilometer tunnel straddling the French-Swiss border.
The Lab has also given a statement about the Forward Search Experiment (FASER) that it will complement CERN’s ongoing physics programme, extending its potential to several new particles. Some of these sought-after particles are associated with dark matter, which is a hypothesized kind of matter that does not interact with the electromagnetic force and consequently cannot be directly detected using emitted light. FASER will search for a suite of hypothesized particles including so-called “dark photons“, particles which are associated with dark matter, neutralinos and others.
“It is very exciting to have FASER approved for installation at CERN. It is amazing how the collaboration has come together so quickly and we are looking forward to recording our first data when the LHC starts up again in 2021,” said Jamie Boyd, co-spokesperson of the FASER experiment.
“This novel experiment helps diversify the physics programme of colliders such as the LHC, and allows us to address unanswered questions in particle physics from a different perspective,” Mike Lamont, co-coordinator of the PBC study group, said in a statement. “The four main LHC detectors are not suited for detecting the light and weakly interacting particles that might be produced parallel to the beam line”, he added.
They may travel hundreds of meters without interacting with any material before transforming into known and detectable particles, such as electrons and positrons. The exotic particles would escape the existing detectors along the current beam lines and remain undetected.
The detector’s total length is under five meters and its core cylindrical structure has a radius of 10 centimeters. It will be installed in a side tunnel along an unused transfer line which links the LHC to its injector, the Super Proton Synchrotron.
A collaboration of 16 institutes is building the detector and will carry out the experiments which will start taking data from LHC’s Run 3 between 2021 and 2023.
The LHC was used in 2012 to prove the existence of the Higgs Boson – dubbed the God particle – which allowed scientists to make great progress in understanding how particles acquire mass.
What is dark matter?
Dark matter is a hypothetical form of matter that accounts approximately 85% of the matter in the universe, and about a quarter of its total energy density. dark matter does not interact with the electromagnetic force. This means it does not absorb, reflect or emit light, thus making it extremely hard to spot. Dark matter seems to outweigh visible matter roughly six to one, making up about 27% of the universe.
February 22, 2019(updated June 5, 2019) Published by Kshitij Kumar
The Higgs Boson God particle has been widely talked about in the recent past. You might have heard people talking about how its discovery has simplified explanations for why electrons have mass. You might have even heard about how it has aided in proving that the Standard Model is not incorrect. The discovery of the particle received tremendous attention from the press, and, was celebrated quite remarkably. So, what is all the fuss about? What really is the Higgs Boson? How does it help explain certain phenomena? Why is it called God particle? If you are looking for answers to any of these questions, or, are simply intrigued and want to know more about the Higgs Boson, then, look no further, you’re at the right place.
The Higgs boson is considered to be the particle excitation of the Higgs field and is named after the physicist, Peter Higgs. Peter Higgs and five other scientists are credited with coming up with the mechanism that provided evidence to the existence of such a particle.
What is all the fuss about then?
The reason there has been so much buzz surrounding the Higgs boson till recently was because its existence was only experimentally proven as recently as 2012. The reason it took so long for scientists to confirm its existence is the fact that the technology needed for confirming the existence of the Higgs boson, had not existed for a very long time. This discovery was a physics version of the discovery of DNA.
The discovery of this particle was made possible by the Large Hadron Collider (LHC). The Large Hadron Collider is a particle collider and is gigantic in nature. It is the largest machine in the world. It is present in a humongous tunnel near Geneva in Switzerland. Without the LHC, it would have been an extremely daunting, and some can even say, an improbable task to prove the existence of the Higgs boson.
You can read everything about search and discovery of Higgs boson here ->The Higgs Boson discovery pdf by CERN
Particle accelerators and the Large Hadron Collider
The Large Hadron Collider is a particle accelerator that is used to accelerate charged atomic and subatomic particles to large enough speeds to observe their behaviour. The Large Hadron Collider is currently the largest among such colliders. The tunnel in which it lies is massive and is 27km in circumference. It was built by the European Organization for Nuclear Research (CERN) and is used for studying the observations made by the collision of particle beams, generally, proton beams.
CERN LHC Particle Collider (Source: CERN)
Particle accelerators such as the LHC are considered to be fundamental in answering some of the questions that remain in the field of particle physics. These accelerators generally use an electromagnetic field to carry out the acceleration. You may ask, why is there a need for an electromagnetic field? To understand this, you will need to know how particle accelerators work. Particle accelerators need to have a source. A source is what generates particles such as protons and electrons. The electric fields are used in the process of accelerating these particles while the magnetic fields are responsible for controlling the paths of these particles.
To generate electrons for these particle accelerators, ‘electron guns’ are generally used. The electron gun consists of a cathode, which, is heated to high temperatures causing electrons to be produced from its surface. The electron gun consists of electrical and magnetic deflectors and the electron beam is obtained from a narrow hole at the end of the gun. This electron gun can also be viewed as an accelerator since it also consists of an electric field that accelerates the electrons, and magnetic deflectors that help in controlling the path. These electrons move towards the anode present in the gun and while passing through the electric field pick up speed and come out of the gun as a narrow beam.
To generate protons for the accelerators, hydrogen gas is used since only the nuclei of hydrogen atoms consist of single protons. The gas is ionized, and the protons and electrons are separated through electric fields and the beam of protons is obtained through a hole.
The beams produced are then collided and the particles that result from the collision are observed by detecting electrical signals. The detectors used in particle accelerators are built so that the electrical signals can be converted to digital data and analyzed. Higgs boson was detected in 2012 during such collisions.
Now that we know how Higgs boson was detected, let’s delve into what it really is.
The Higgs boson is a particle that is generated by the quantum excitation of the Higgs field. You may ask, what is the Higgs field? Well, the Higgs field is a field that exists evenly distributed throughout the universe. Some particles are said to interact with this field and obtain mass while some particles are said to not interact with it. The Higgs field is quite dissimilar to other fields, since, it is scalar. A scalar field is one where every point in the field can be associated with a scalar value.
So, what does that mean? It means that the Higgs field is directionless, it has a spin value of 0. Unlike other fields such as electromagnetic fields, the Higgs field has no preferred direction.
The particles carrying the strong force are the:
The strong interaction is observable at two ranges: on a larger scale (about 1 to 3 fm), it is the force that binds protons and neutrons (nucleons) together to form the nucleus of an atom. On the smaller scale (less than about 0.8 fm, the radius of a nucleon), it is the force (carried by gluons) that holds quarks together to form protons, neutrons, and other hadron particles.
What is all this stuff about the Standard Model then?
All things in this world are constituted by atoms. Atoms, in turn, are made up of protons, neutrons and electrons. These particles are made up of even smaller subatomic particles. The Standard Model was able to explain the interactions between these subatomic particles and hence provided the basis for the explanations of electricity, magnetism and radioactivity. However, the Standard Model, before the discovery of the Higgs boson, was unable to provide evidence for how these particles gained mass.
This is where the Higgs field comes into play. Like I mentioned earlier, some particles interact with this field, while some do not. The ones that do not interact with this field, like the photons, do not gain mass and can hence travel at the speed of light. The ones that do interact with this field, like the electrons, gain mass through the interactions. Think of it this way, if the Higgs field did not exist, there would be no interactions with the field and therefore, all subatomic particles would have no mass.
Why is the Higgs Boson called the God particle?
Perhaps, the term ‘God particle’ is justified. The Higgs boson helped fill a large hole in the Standard Model and is considered to have provided evidence that proves a large number of phenomena. In some sense, this particle is truly Godly!
But, the term ‘God particle’ arises from the title of Leon Lederman’s book, ‘The God Particle’, in which, the Higgs boson is the primary subject of discussion. Leon Lederman is credited with providing this particular title to the particle. But, the story is actually even more fascinating. Lederman wanted to title his book as ‘The Goddamn Particle’ because of how difficult it is to find the particle and actually prove its existence. His publishers, however, would not allow for such an audacious title and the book was then titled ‘The God Particle’.
Is this particle dangerous? Can it prove to be detrimental?
Stephen Hawking has cautioned the world about the potential dangers that the Higgs boson might harbour. Some researchers believe that this particle could lead to the destruction of the universe. However, this destruction will not take place anytime soon. These researchers estimate that this catastrophe is at least billions of years away. The mass of the Higgs field will be to blame if this occurs. Since the Higgs field is present everywhere, even a small change in its mass would cause major instability in the universe, causing the universe to collapse.
Six years ago today, physicists at the Large Hadron Collider announced the detection of the Higgs Boson, completing the Standard Model of Particle Physics and possibly indicating a disastrous fate for our Universe. https://t.co/UdtB3yD8ef#Higgs#VacuumDecay
In conclusion, the Higgs boson is the result of the excitation of the Higgs field. The Higgs field is a scalar field that provides mass to the subatomic particles that interact with it. Without the Higgs field, all subatomic particles would have no mass. This entire mechanism was suggested by Peter Higgs and five other scientists in 1964. The Higgs boson, however, was not discovered until 2012, when it was first discovered by the Large Hadron Collider, which, is a particle accelerator. The name ‘God particle’ was the result of Lederman’s similarly titled book about the Higgs boson.
Although the ‘God particle’ certainly seems to be a misnomer, the name given to the Higgs boson might have done the world a whole lot of good. The title given to the particle has ensured that more and more people look for the Higgs boson on the internet and try to understand what it means and how much effort has been put in, to find it. The name, ‘God particle’ could even be the reason why you are currently reading this. Any scientist would give you the death stare for calling the Higgs boson, the ‘God particle’, but, maybe the name is not so bad after all. Perhaps, the magnitude of the reception of the news of the discovery of Higgs boson should be entirely credited to this misnomer!
February 5, 2019(updated August 24, 2019) Published by Kshitij Kumar
There are a lot of objects and bodies that exist in this gargantuan universe of ours. Everything in this vast abode that we call the universe, whether big or small, is said to consist of matter. Your phone, your body, your hair, dust, air and everything you see around is matter. Each and every one of these objects consists of matter and their existence can generally be perceived rather easily.
Estimated division of total energy in the universe into matter, dark matter and dark energy based on five years of WMAP data (Credit: Wikipedia)
But what if I told you that most of the matter that exists in the universe cannot be perceived? What if I also told you that more than 85% of the matter in the universe has never been observed? These facts are hard to believe and are rather astounding, but, they are, indeed, facts. There is a special kind of matter called Dark matter, which constitutes about 85% of all the mass of universe and has never been observed directly.
Indeed, talking about the energy composition the universe is composed of roughly 4.6% matter, 23% dark matter and 72% dark energy (this is energy composition not to be confused with the above-mentioned mass composition). It is thought that we can neither detect nor measure dark energy but we can clearly see its implications. Let us talk about Dark matter in this blog and keep Dark energy aside for another blog.
To understand about Dark Matter, you have to understand about Matter first. The matter is something that has mass and occupies space. Matter can exist in any form or state. There are seven states of matter and they are:
Matter consists of atoms, or, to be precise, the matter is made up of protons, neutrons, and electrons. This matter is called “Ordinary Matter”. The sub-atomic particles are built with some fundamental particles. These particles can be put into two groups: fermions and bosons. Fermions are the building blocks of matter. They all obey the Pauli exclusion principle. Bosons are force-carriers. They carry the electromagnetic, strong, and weak forces between fermions.
Fermions can be put into two categories: quarks and leptons. Quarks make up, amongst other things, the protons and neutrons in the nucleus. Leptons include electrons and neutrinos. The difference between quarks and leptons is that quarks interact with the strong nuclear force, whereas leptons do not.
There are four bosons in the right-hand column of the standard model. The photon carries the electromagnetic force – photons are responsible for electromagnetic radiation, electric fields and magnetic fields. The gluon carries the strong nuclear force – they ‘glue’ quarks together to make up larger non-fundamental particles. The W+, W– and Z0 bosons carry the weak nuclear force. When one quark changes into another quark, it gives off one of these bosons, which in turn decays into fermions.
All the above particles make up the Standard Model of particles and dark matter doesn’t come in this standard model
There are many observations which strongly suggests the presence of some strange non-luminous matter or the dark matter. Let us see some of them:
The speed of bodies located farther from the galactic centre: From Kepler’s Second Law, it is expected that the rotation velocities will decrease with increase in the the distance from the centre of the galaxy, similar to the Solar System. This is not observed and the only obvious reason we could find is the presence of Dark matter.
Mass velocity discrepancy: Stars in bound systems must obey the Virial theorem which together with the measured velocity distribution, can be used to measure the mass distribution in a bound system, such as elliptical galaxies or globular clusters. However, some velocity dispersion estimates of elliptical galaxies do not match the predicted velocity dispersion from the observed mass distribution. This discrepancy also tells that there is some extra invisible mass out there.
Gravitational Lensing: Galaxies and other huge interstellar objects act as a lens and bends light. Actually, these massive things distort or bend the fabric of space-time and light passing through this distortion bends. So, the bending of light clearly depends on the mass of the galaxy. Researchers have made many such observations of light coming from quasars through some galaxy clusters. The bending of that light clearly tells that there is some extra mass out there.
Cosmic Microwave Background: The Cosmic Microwave Background radiation or CMB for short is basically electromagnetic radiation which has been travelling for these 14 billion years since the big bang. This has the temperature data also. Scientists have collected a lot of data from this radiation and created a map. This map perfectly matches with the Dark matter model and clearly tells that the universe cannot exist without Dark Matter.
9-year WMAP image of cosmic microwave background (Credit: NASA)
Like this, there are many other proofs but these four are the most prominent proofs for the existence of some unknown and invisible matter out there.
Types of dark matter
The classification of dark matter is based on its velocities. Free streaming length (FSL) is used to describe the distance objects would travel due to the random motions in the early universe. The size of a protogalaxy is used for determining the category of dark matter.
Cold dark matter: Dark matter whose constituents have an FSL less than the size of a protogalaxy.
Warm dark matter: Dark matter whose constituents have an FSL comparable to the size of a protogalaxy.
Hot dark matter: Dark matter whose constituents have an FSL greater than the size of a protogalaxy.
Why should we find dark matter?
Dark matter constitutes 85% of the Universe’s Mass and it is present in really huge quantity and a lot of it might be present here on earth as well. If detected, we could probably use it for energy production and many other unbelievable applications might come up.
Other than applications, dark matter could unveil some of the dark secrets of the universe which are lying unanswered for centuries.
What could dark matter be made of?
There are several theories about what dark matter could be made of and some of them are:
WIMPs(Weakly interacting massive particles): WIMPs are hypothetical particles that are thought to make the dark matter. These are totally new particles interacting through weak forces which are probably weaker than the weak nuclear force. These particles are not included in the above-mentioned standard model. Researchers are trying and developing a lot of experiments to detect such particles.
Axions: Axion is another hypothetical elementary particle. It was actually postulated to solve the strong CP problem in quantum chromodynamics. Scientists believe that if they axions exist and have some specific properties then they can be a possible component of dark matter.
Like this, there are many proposed things and to understand all these hypothetical particles, we need a deeper understanding of physics. There are theories also saying that the current understanding of gravity itself is wrong and should be modified according to the observations but there are limitations to this also.
How could we detect dark matter?
We can locate the places in the universe where dark matter is present using techniques like Gravitational Lensing and we can even create the model of galaxies including dark matter. But we are not yet able to detect the particles which make this dark matter. So, how could we detect dark matter? Let us discuss the possible approaches. Basically, there are three approaches and they are:
Large Underground Xenon detector inside watertank (Credit: Wikipedia)
Make it here: Physicists have been bombarding particles in accelerators like LHC and there is a hope that someday we create dark matter particles and hopefully detect them.
Direct Detection: Considering the amount of dark matter present in the universe, there is a possibility that dark matter is present here on earth as well and there is a possibility that some sensitive detector could detect it. So, scientists have been building extremely sensitive detectors to detect dark matter. One such detector is The Large UndergroundXenon experiment (LUX) aimed to directly detect weakly interacting massive particle (WIMP) interactions with the ordinary matter on Earth
Dark matter collisions: Scientists believe that collisions of dark matter could probably release something which we could detect. So, researchers are trying to use this approach as well.
The Pauli's Exclusion principle states that two electrons in same orbitals have:
The Pauli Exclusion Principle states that, in an atom or molecule, no two electrons can have the same four electronic quantum numbers. As an orbital can contain a maximum of only two electrons, the two electrons must have opposing spins.
Why is dark matter still a mystery?
While dark matter is the simplest explanation for the extra gravity and mass that exists, it is not necessarily the correct explanation. There are several theories that claim to explain this extra gravity and mass in the universe. Nobody really knows for sure if the existence of dark matter is a sufficient enough explanation for the existence of the extra mass. Dark matter does not give off light and as I have mentioned, does not interact with particles. Without any interactions, it is extremely hard to derive any conclusions on its nature and properties.
A recent paper in the physical review journals gave the maths claiming that dark matter might be created before the big bang itself which ads another mystery to the already existing mysteries around dark matter
Dark matter may be considered as the universe’s biggest mystery. It is known that something makes objects faster than they should but we do not actually know what it is and where it came from. The origins of dark matter might be even more peculiar than it is known.
Jonathon Swift, an Anglo-Irish poet once said, “Vision is the art of seeing what is invisible to the others”. Dark matter may be invisible, but it has served to solve a lot of mysteries in this astonishingly mysterious universe. Without the invisible phenomenon of dark matter, there would still be a lot of perplexity regarding the formation of galaxies and their movements. Despite all the information we possess about the universe, nobody can say with certainty that dark matter exists. Perhaps, that is where the magnificence of physics lies, in its mystery, and this mystery is what makes the search for the truth worthwhile.
February 5, 2019(updated July 10, 2019) Published by Kshitij Kumar
Gravitational waves were proposed by Henri Poincaré in 1905 and subsequently predicted in 1916 by Albert Einstein on the basis of his general theory of relativity. There are so many aspects of physics that are aesthetically pleasing. These aspects are not necessarily pleasing due to their visible or on the surface features, rather, they are aesthetically pleasing in their detail. Gravitational waves are certainly one such phenomenon. They have immense importance, and their impact in understanding the theories of physics is considerably high.
Gravitational waves are ripples in the fabric of space-time that are formed due to the acceleration of masses. These ripples propagate outwards from the source of mass. One must understand that distortions are created in the fabric of space-time by bodies of mass. To visualize this concept, think of this fabric as a piece of paper or a blanket, with people holding on to it from all sides. When an object of mass is placed on the paper or blanket, there is a visible dent or distortion of the shape of the paper or blanket at the position where the object was placed. Now when these bodies of mass are moved about, that is, they are provided acceleration, these distortions also move about in the fabric of space-time. These accelerated bodies lead to the formation of waves in space-time. These waves are the gravitational waves.
As you would imagine, larger bodies tend to create larger intensity waves. Theoretically, any movement of a body having mass can cause these ripples. A person walking on the pavement, in theory, also causes these ripples. However, these ripples caused by a walking person are very minuscule and insignificant.
So, what is space-time?
The universe was long thought to be consisting of the three dimensions of space only. But, Albert Einstein proved that the universe consisted of a fourth dimension, time. It would be impossible to move in space without moving in time. Similarly, it would also be impossible to move in time without moving in space. Space and time, therefore, have a very integral relationship. Einstein stated that there is a profound link between motion through space and passage through time. He hypothesized that time is relative. Objects in motion experience time slower than objects at rest.
The three dimensions of space and the dimension of time are viewed as the four-dimensional space-time. Hermann Minkowski provided a geometric interpretation that fused the three dimensions of space and the dimension of time to form the space-time continuum. This was called the Minkowski space.
Minkowski Space Illustration. Image Source: Wikipedia
In three dimensional space, the distance, D between any two points can be represented using the Pythagorean theorem as:
D2=(Δx)2 + (Δy)2 + (Δz)2
Δx represents the difference in the first dimension, Δy represents the difference in the second dimension and Δz represents the difference in the third dimension
The spacetime difference of two points given by (Δs)2 varying by time Δt would be given as:
(Δs)2=(Δct)2 – (Δx)2 + (Δy)2 + (Δz)2
c is a constant, representing the speed of light that enables conversion of units used to measure time to units used to measure space.
Gravitational pull and formation of waves
Every body that has mass tends to attract other bodies. Whether the mass is small or large, every body exerts a force on the other. This attraction is the gravitational pull. The greater the mass of the object, the larger its gravitational pull. The larger the distance of an object from another object, the lower its gravitational pull on it. Since every object, however large or small, tends to exert this pull on every other object, changes in gravity can provide insight into the behaviour of these objects.
If the distance between two bodies is doubled, the force of attraction F between them will be:
Since the force of gravity acting between any two objects is inversely proportional to the square of the separation distance between the object's centers, Force F will be reduced by 1/2 x 1/2 = 1/4 times.
Consider the earlier example of the distortion caused by placing an object on paper or blanket, now, if we were to place a larger object, this would result in an even larger distortion. The larger object would cause a larger depression in the paper or blanket and hence, is said to have larger gravity. If the two objects were placed on the paper or blanket together, the larger object with the larger distortion would seem to be exerting a larger force of attraction towards the other object. If these objects moved, there would be ripples formed on the paper or blanket. This is similar to how gravitational waves are formed, the only difference being that the paper or blanket would be replaced by the fabric of space-time.
These gravitational waves cannot be felt easily. To detect these, you would require special equipment. These detectors are L shaped instruments with generally long arms.
Detection of gravitational waves
Gravitational waves were first witnessed in September 2015. Scientists observed the waves that were a result of two black holes colliding. These black holes were said to possess masses several times that of the sun. The black holes were attracted to each other due to the gravitational forces and slowly, over the course of several years, began to spiral into each other. One day, they finally merged. Before they merged, they let out gravitational waves that were felt on earth billions of years later in 2015.
This was picked up by a detector called Laser Interferometer Gravitational Wave Observatory (LIGO). This signal was very short lived and lasted only a fifth of a second. These wobbles in space-time picked up by the LIGO was thousands of times smaller than the nuclei of atoms. This is because the gravitational waves over the course of time gradually became weaker. The Laser Interferometers were configured in such a way that even these small ripples could be picked up.
LIGO consists of two gigantic laser interferometers located thousands of kilometres apart. Each detector consists of two 4km long steel vacuum tubes arranged in an ‘L’ shape. A special covering is provided to these tubes to ensure protection from the environment.
Aerial view of the LIGO Hanford Observatory. (Source: Caltech/MIT/LIGO Laboratory)
These tubes are the arms. The lengths of these arms are measured with lasers. If the lengths are changing, this could be due to compression and relaxation of arms due to gravitational waves. Studying these gravitational waves enables scientists to derive certain information about the objects that produced them. Information such as the mass and size of the orbit of the object that created the wave can be extracted from studying these gravitational waves. In the year 2017, The Nobel Prize in Physics was received by Rainer Weiss, Kip Thorne and Barry Barish for their role in the detection of gravitational waves.
Today, LIGO is trying to detect Gravitational waves with even more sensitive instruments in hope to detect more merging neutron stars and black holes and maybe some new discoveries too
These gravitational waves help scientists gain information about the physical properties of the objects that created the waves. These gravitational waves provide a new way to observe the universe. A way that never existed previously.
The detection of the gravitational waves allows us to understand interactions in the universe in a completely new way. The waves detectable by LIGO are waves generated due to the collision of two black holes, exploding stars, or perhaps the birth of the Universe.
Before this form of understanding the universe was realized, most observations of the universe were made based on electromagnetic radiation. Something like the collision of black holes would have been impossible to have been picked up by electromagnetic radiation.
A major difference between gravitational waves and electromagnetic waves is the fact that gravitational waves interact very weakly with matter. Electromagnetic radiation, on the other hand, reacts strongly with matter and could face several alterations in its properties. Gravitational waves can travel through the universe virtually unimpeded.
The information, such as the mass and orbit of the object that caused the waves could be understood in a clearer manner. The information carried by the waves is free from any alterations or distortions that result from interaction with matter present in the universe.
The gravitational waves can also penetrate regions of space that electromagnetic radiation cannot. These properties have led to the creation of a new field of astronomy, called gravitational field astronomy. Gravitational field astronomy aims to study large entities in the universe and their interactions through unadulterated properties of gravitational waves.
Famous basketball player, John Wooden once said, “It’s the little things that are vital. Little things make big things happen”. In the case of gravitational waves, the little things are the ones that provide the knowledge of the larger things. Little observations made on the properties and complexities of the gravitational waves are what gives rise to the details pertaining to the larger bodies existing in the universe. There is no denying the fruitfulness of the existence of gravitational waves. One can even go so far as to say that gravitational waves have revolutionized physics. I can say without a cloud of uncertainty that gravitational waves will surely help us uncover more secrets of the universe in the future.
February 5, 2019(updated July 10, 2019) Published by Kshitij Kumar
We all travel in time, don’t we? From the last year, we’ve moved up one year. Another way to say this is that we all are travelling forward at the same speed. But our topic at hand is, can we travel faster or slower? Or can we travel backwards or forward in time? It is indeed kind of mind-boggling to wrap our whole head around that concept. And there are countless imaginative theories. What if time-travel was possible? Would we be able to prevent something bad from happening? But if so, then what’s the guarantee that something more ominous might not happen? Let us dive deep into the depth of it all. Is all of this science fiction or is it truly possible?
To understand the concepts of time travel you need to understand a few theories and about a few hypothetical things.
The first name we get to our mind while talking about Time Travel is Albert Einstein and his Theory of Relativity. Understanding these theories completely is very difficult and there are very less people in the world who understand it completely. But this theory proves two special things with which we can travel in time. They are
1. If we travel with speeds closer to the speed of light, time will move slower for us (by the Special Theory of Relativity). But achieving such speed is very difficult and the reason again comes from Einstein. Einstein gave a mass velocity relation which tells that our inertial mass increases with velocity. The equation is
Einstein’s Mass Velocity Equation
v is the magnitude of the velocity
c is the speed of light
m0 is the rest mass of the body
m is the relativistic mass
2. Gravity distorts space and time and time moves slower in places with high gravitation (by the General Theory of Relativity). Know more about Gravity time dilation.
The Theory of General Relativity predicts the existence of something called Wormholes. A wormhole is a special solution to Einstein’s Field Equation. Wormholes are like passages or shortcuts between two points in space. Physicists say that we can travel in time through Wormholes but there are serious problems. We will discuss the problems in the next section.
One more hypothetical thing one needs to know is Exotic Matter. Exotic Matter is such a matter which have negative mass and repels the mass we see. At first, scientists believed that exotic matter cannot exist as it contradicts Einstein’s theories but some of the researchers have claimed that they have found a solution to Einsteins General theory of relativity which allows the existence of negative mass.
The BBC’s long-running science-fiction series Doctor Who, celebrating its fiftieth day of remembrance on twenty-three Nov, centres on its name character’s adventures through time and house. However, he may extremely skip between totally different periods of history at will?
Travelling forwards in time is amazingly simple. Einstein’s special theory of relativity, developed in 1905, made it clear that if we can travel at speeds close to the speed of light, we can travel into the future. Thanks to Einstein
If one were to go away from Earth inside a spacecraft moving at a considerable fraction of light speed, and is available back, solely a number of years may need to be passed on board however many years may have gone along on Earth. This leads to the “twins paradox“. What is twins paradox? Suppose one of a twin goes on the above-mentioned spacecraft and comes back, he would find himself much younger than his twin.
There’s just one drawback, once after you travel into future, coming back to the time where you started is difficult. There is a possibility of travelling back in time if traversable wormholes exist in reality. Wormholes are known to exist at microscopic levels and even if traversable wormholes exist they would collapse in seconds because of gravity. To keep Wormholes open we would need Exotic matter which is still hypothetical.
Assuming exotic matter exists and wormholes also do, even then we can’t go to any point in past. First of all, we need to have a machine to travel through a wormhole and with that machine we can travel back only to the time when the machine was created. Even if we create machines which have no effect with time and if could travel back to any point in time, we still have problems like the Grandfather paradox.
More restrictively still, theoretical work by Kip Thorne of Caltech employing a partial unification of general theory of relativity with natural philosophy recommended that any hole that enables time travel would collapse as before long because it fashioned. Thorne did, however, resolve a noticeable issue that might arise because of my time travel (within the orbit of general relativity). The “grandfather paradox” involves going back in time and accidentally killing one’s grandfather before one’s father is planned – preventing one’s own birth.
Not only that, if time travel becomes possible anyone could go into the past and change the future randomly which is very dangerous.
Some paradoxes and facts about Time-Travel
Time Travel (Credi: Pixabay)
Infinite Loop Paradox
A man travels back into the past and marries a woman. After that, he returns to the present. The woman whom he married gets pregnant and has a son. After a few years, that son becomes the time traveller who goes to the past and marries the woman.
So who is the son and who is the father?
Stephen Hawking once believed that time travel is impossible
Stephen Hawking used to think that time travel is impossible. He claimed there would be some physical law which would prevent time travel and he even named it as “chronology protection conjecture”. But in the following years, unable to find any such physical law, he changed his statement and he stated as below
Many researches have proved that time flows quickly on higher altitudes on earth. Scientists have compared time from two atomic clocks, one was on a mountain and one was at sea level. The clock on the mountain was faster by 90 Billionths of a second.
So if you want to add a few billionths of a second to your life, stay in basements.
4. End of Humans Paradox
If someone travels back in time and kills the first human, there should be no life and the human who went there should disappear. What? These paradoxes really sound terrific.
There are many other paradoxes and theories, people say that
All great scientists could probably be time travels and didn’t know how to go back
All the amazing structures like the Pyramids, Kailashnath Temple etc might be built by the time travellers and the list goes on
Space and time are two sides of the same coin
Space And Time are simultaneous phenomena (like mass and energy), and together form the fabric of the universe known as space-time. A demonstration of four-dimensional space-time’s inseparability is the fact that, as astronomers often remind us, we cannot look into space without looking back into time. We see the Moon as it was 1.2 seconds ago and the Sun as it was 8 minutes ago.
Also, in accordance with Einstein’s general theory of relativity, a massive object in space stretches the fabric of both the space and time around it. For example, our Sun’s mass bends its surrounding space so that the Earth moves in a straight line but also circles within the Sun’s curvature in space. The Sun’s effect on time is to slow it down, so time runs slower for those objects close to the massive object. Interestingly, gravity is the result of mass stretching the fabric of the space-time around it. Gravity also has an infinite range such that no matter how far apart two masses are in space they will always experience some gravitational pull towards each other. Theoretical physicists have tried to explain this phenomenon in terms of gravitons, S-Theory, and M-Theory, but even today a successful quantum theory of gravity is yet to be found.
While time travel does not appear possible — at least, possible in the sense that the humans would survive it — with the physics that we use today, the field is constantly changing. Advances in quantum theories could perhaps provide some understanding of how to overcome time travel paradoxes.
One possibility, although it would not necessarily lead to time travel, is solving the mystery of how certain particles can communicate instantaneously with each other faster than the speed of light.
In the meantime, however, interested time travellers can at least experience it vicariously through movies, television and books.
February 5, 2019(updated May 27, 2019) Published by Kshitij Kumar
The secret of how life on Earth began
How did life begin? There will hardly be a much bigger question. For the abundance of human history, nearly everybody believed some version of “the gods did it”. The other rationalization was out of the question.
Is the existence of life on Earth a lucky fluke or associate inevitable consequence of the laws of nature? Is it easy forever to emerge on a fresh fashioned planet, or is it the nearly not possible product of an extended series of unlikely events? Advances in fields as disparate as uranology, planetary science and chemistry currently hold promise that answers to such profound queries could also be around the corner. If life seems to possess emerged multiple times in our galaxy, as scientists hope to find, the trail thereto can’t be thus exhausting. Moreover, if the route from chemistry to biology proves easy to traverse, the universe might be abundant with life.
During a beautiful surprise, most the fresh discovered star systems look terribly totally different from our own. Will that mean one thing regarding our own, very odd, system favors the emergence of life? sleuthing signs of life on a planet orbiting a foreign star isn’t getting to be simple, however, the technology for teasing out delicate “biosignatures” is developing thus chop-chop that with luck we tend to may even see distant life at intervals one or 20 years.
Experiments to figure out origins
In 1952, Stanley Miller was operating with Harold C. Harold Urey designed associate experiment to visualize however advanced organic molecules might need to be fashioned underneath the conditions of early Earth. They believed the first Earth atmosphere would are composed of an alkane series, ammonia, chemical element, and vapor. They sealed these gases in associate airtight instrumentality, and then exposed the gases to sparks of electricity to simulate lightning. They continued the lightning for per week, and by the top, an achromatic substance had coated the walls of the instrumentality. This substance contained eleven of the twenty amino acids employed by life on earth. Since Miller and Harold Urey performed this experiment, its results are confirmed over and over by different scientists. Several scientists currently believe that the first Earth’s atmosphere was composed of carbonic acid gas, nitrogen, and vapor.
Image Source: Wikipedia
Modern experiments with this mixture of gases manufacture similar results suggesting that early conditions on Earth made advanced organic molecules that in all probability became the premise for the event of additionally advanced organisms. However, scientists haven’t been able to replicate the formation of even easy organisms or something which will very replicate itself. There square measure many theories on however the amino acids might need to be created the leap into the advanced, self-replicating life we tend to see nowadays.
Before the 1800s, the general public believed in “vitalism”. This is often the intuitive concept that living things were blessed with a special, charming property that created them totally different from inanimate objects.
The chemicals of life will all be made up of easier chemicals that don’t have anything to try and do with life
Vitalism was typically certain up with cherished spiritual beliefs. The Bible says that God used “the breath of life” to animate the primary humans, associated an immortal soul may be a type of philosophical theory.
There is only 1 drawback. A philosophical theory is obviously wrong.
By the first 1800s, scientists had discovered many substances that appeared to be distinctive to life. One such chemical was an organic compound that is found in excretion and was isolated in 1799.
This was still, just, compatible with philosophical theory. Solely living things appeared to be ready to create these chemicals; therefore maybe they were infused with life energy which was what created them special.
But in 1828, the German chemist Friedrich Wöhler found some way to form organic compound from a typical chemical known as ammonia cyanate that had no obvious reference to living things. Others followed in his footsteps, and it had been presently clear that the chemicals of life will all be made up of easier chemicals that don’t have anything to try and do with life.
This was the top of philosophical theory as a scientific construct. However, individuals found it deeply arduous to giving up of the thought. For many, the expression that there’s nothing “special” regarding the chemicals of life appeared to rob a lifetime of its magic, to cut back the United States to mere machines. It also, of course, contradicted the Bible.
The mystery of life’s origin was unheeded for many years
Even scientists have struggled to shed philosophical theory. As late as 1913, English chemist Benjamin Moore was fervidly pushing a theory of “biotic energy”, that was basically philosophical theory below a special name. The thought had a robust emotional hold.
Today the thought clings on in sudden places. As an example, there are lots of science-fiction stories during which an individual’s “life energy” is boosted or drained away. Consider the “regeneration energy” employed by the Time Lords in Doctor United Nations agency, which might even be lidded up if it runs low. This feels futurist, however, it’s a deeply old school plan.
Still, when 1828 scientists had legitimate reasons to seem for a deity-free rationalization for the way the primary life shaped. However, they didn’t. It feels like a plain subject to explore, however in reality, the mystery of life’s origin was unheeded for many years. Maybe everybody was still too showing emotion connected to philosophical theory to require consecutive step.
Darwin’s Theory of Evolution
Darwin’s theory, come into being in On the Origin of Species in 1859, explained however the immense diversity of life may all have arisen from one common relative. Rather than every one of the various species being created separately by God, they were all descended from a primeval organism that lived uncountable years past the last universal common relative.
This idea established vastly controversial, once more as a result of it contradicted the Bible. Darwin and his ideas came underneath furious attacks, significantly from angry Christians.
Charles Darwin’s Theory of Evolution Illustration. Image Source: ConexaoCabeca (Pixabay)
Darwin knew that it absolutely was a profound question, however – maybe cautious of beginning one more fight with the Church – he solely appears to possess mentioned the difficulty in an exceeding letter written in 1871.
The first hypothesis for the origin of life was unreal in an exceedingly brutally totalitarian country
“But if (what a giant if) we tend to may conceive in some heat very little pool with all kinds of ammonia salts,—light, heat, electricity &c gift, that a macromolecule compound was with chemicals fashioned, able to endure still additional complicated changes…”
In alternative words, what if there was once a tiny low body of water crammed with easy organic compounds and bathed in daylight. a number of those compounds would possibly mix to create a life-like substance like a macromolecule, that may then begin evolving and changing into additional complicated.
What came first?
Some scientists believe that metabolism, in different words – the power to interrupt down greenhouse gas within the presence of a catalyst into tiny organic molecules – was, however, the primary life developed. These reactions may need to be evolved to become additionally complicated, and then genetic molecules somehow shaped and joined in later. There are many alternative theories on specifically what sorts of molecules and catalysts would are concerned.
Other scientists believe that the primary living organisms were genes. These genes were single molecules that had developed in such some way on be ready to catalyze their own replication. This theory looks additional possible since even easy systems like crystals are incontestible to evolve with modifications that breed true. Some scientists have urged that bound compositions of clay produce the correct surroundings for these reactions to propagate.
RNA could be a complicated molecule found altogether living things that appear to be ready to catalyze its own copy. Several scientists believe that straightforward ribonucleic acid molecules developed and eventually became a lot of complicated and developed into the organisms we have a tendency to see these days.
Astrobiologists and biochemists wish to grasp one thing they decision LUCA (the Last Universal Common Ancestor). The thought is that every one life on Earth encompasses a common ascendant, reasonably sort of a great-great-great-….-great grandparent. They rummage around for traits that are common across all life forms and assume that any traits that are common to any or all life forms nowadays should are familial from LUCA, WHO had all furthermore.
Last Universal Common Ancestor. Image Source: Wikipedia
Biochemists recognize quite a bit concerning LUCA and her organic chemistry. She keeps her genetic info in DNA, she had many hundred proteins performing arts a range of functions, and she or he used a similar twenty amino acids we tend to use in our proteins. She used polymer and had some reasonably double-layer macromolecule membrane. She was in all probability the ascendant of the 3 kingdoms of life: Archaea, Eukaryotes, and bacterium.
LUCA lived a minimum of a pair of billion years past before there was a lot of atomic number 8 within the atmosphere. She used enzymes containing iron in her metabolic pathways the approach a lot of life on early Earth did. Learning however life arose on Earth is helpful to astrobiologists, however, they confine mind that the approaching life shaped on Earth isn’t the sole approach life may have shaped. It’s merely a method that it did.
What next? Chemists are already asking whether or not our quiet life are often generated solely through one plausible pathway or whether or not multiple routes would possibly lead from easy chemistry to RNA-based life and on to trendy biology. Others are exploring variations on the chemistry of life, seeking clues on the attainable diversity of life “out there” within the universe. If all goes well, we are going to eventually learn the way strong the transition from chemistry to biology is and so whether or not the universe is packed with life-forms or—but for us—sterile.
Every single one that died before Darwin revealed the Origin of Species in 1859 was blind to humanity’s origins, as a result of they knew nothing of evolution. However everybody alive currently, riddance isolated teams, will recognize the reality regarding our kinship with alternative animals.
Similarly, everybody born when spaceman orbited the world in 1961 has lived in a very society that may jaunt alternative worlds. Notwithstanding we tend to ne’er go ourselves, voyage may be a reality.
Our world views these modifications in delicate ways. Arguably, they create the North American nation wiser. Evolution teaches the North American nation to treasure each alternative animate thing, for they’re our cousins. The voyage permits the North American nation to visualize our world from a distance, revealing however distinctive and fragile it’s.l honestly say they recognize wherever they came from. They’ll recognize what their final antecedent was like and wherever it lived.
This knowledge cans modification of the North American nation. On a strictly scientific level, it’ll tell the North American nation regarding however probably life is to create within the Universe, and wherever to seem for it. And it’ll tell the North American nation one thing regarding life’s essential nature. However on the far side that, we tend to cannot nevertheless recognize the knowledge the origin of life can reveal.
February 5, 2019(updated May 27, 2019) Published by Kshitij Kumar
Dark Matter & the Ultimate Fate of the Universe
So what is dark energy?
Well, the easy answer is that we do not recognize.
It looks to contradict several of our understandings regarding the manner the universe works. We all recognize that light-weight waves, conjointly known as radiation, carry energy. You feel that energy the instant you step outside on a hot summer day.
More is unknown than is thought. we all know what quantity dark energy there’s as a result of we all know however it affects the universe’s enlargement. apart from that, it’s an entire mystery. however, it’s a very important mystery. It seems that roughly sixty-eight of the universe is dark energy. matter makes up concerning twenty-seventh. the remainder – everything on Earth, everything ever determined with all of our instruments, all traditional matter – adds up to but five-hitter of the universe. come back to think about it, perhaps it should not be referred to as “normal” matter the least bit since it’s such a tiny low fraction of the universe.
One clarification for dark energy is that it’s a property of area. the physicist was the primary person to understand that a vacant area isn’t anything. the area has superb properties, several of that are simply starting to be understood. the primary property that Einstein discovered is that it’s potential for extra space to come back into existence.
Then one version of Einstein’s gravity theory, the version that contains a constant, makes a second prediction: “empty space” will possess its own energy. as a result of this energy may be a property of the area itself, it’d not be diluted as area expands. As extra space comes into existence, a lot of this energy-of-space would seem. As a result, this way of energy would cause the universe to expand quicker and quicker. sadly, nobody understands why the constant ought to even be there, abundant less why it’d have precisely the right worth to cause the discovered acceleration of the universe.
Another rationalization for the way house acquires energy comes from the scientific theory of matter. during this theory, “empty space” is really choked with temporary (“virtual”) particles that regularly type and so disappear. however once physicists tried to calculate what quantity energy this is able to offer empty house, the solution came out wrong – wrong by a great deal. the amount came out 10120 times too massive. that is a one with a hundred and twenty zeros once it. It’s laborious to urge a solution that unhealthy. that the mystery continues.
Another rationalization for dark energy is that it’s a brand new quite high-octane energy fluid or field, one thing that fills all of the areas however one thing whose result on the enlargement of the universe is that the opposite of that of matter and traditional energy. Some theorists have named this “quintessence,” when the fifth part of the Greek philosophers. But, if quintessence is that the answer, we have a tendency to still do not know what it’s like, what it interacts with, or why it exists. that the mystery continues.
The last chance is that Einstein’s theory of gravity isn’t correct. that will not solely have an effect on the enlargement of the universe, however, it might additionally have an effect on the method that ordinary matter in galaxies and clusters of galaxies behaved. This truth would supply the way to make your mind up if the answer to the dark energy downside may be a new gravity theory or not: we have a tendency to might observe however galaxies close in clusters. however, if it will prove that a brand new theory of gravity is required, what quite a theory would it not be? however, might it properly describe the motion of the bodies within the system, as Einstein’s theory is thought to try toto, and still provide the U.S.A. with the various prediction for the universe that we have a tendency to need? There area unit candidate theories, however none area uncompelling. that the mystery continues.
The issue that’s required to make your mind up between dark energy potentialities – a property of area, a brand new dynamic fluid, or a brand new theory of gravity – is additional knowledge, higher knowledge.
Dark energy or dark matter?
Dark energy makes up most of the universe, however, substance additionally covers a sizeable chunk. Comprising nearly twenty-seven p.c of the universe, and eighty p.c of the matter, substance additionally plays a dominant role.
Like dark energy, substance continues to confound scientists. whereas dark energy could be a force that accounts for the increasing universe, substance explains, however, teams of objects operate along.
In the Fifties, scientists learning different galaxies expected gravity to cause the centres to rotate quicker than the outer edges, supported the distribution of the objects within them. To their surprise, each region revolved at a similar rate, indicating that the spiral galaxies contained considerably a lot of mass than they perceived to. Studies of gas within elliptical galaxies and of clusters of galaxies disclosed that this hidden matter was unfolded throughout the universe. Scientists have a variety of potential candidates for substance, move to unbelievably dim objects to strange particles. however, regardless of the supply of each substance and dark energy, it’s clear that the universe is stricken by things that scientists cannotconventionally observe.
The fate of the Universe
The evolution of the universe is ruled by the number of matter and dark energy it contains, however, the densities of matter and dark energy—their concentrations inside given volume of space—are affected terribly otherwise by cosmic growth. we have a decent plan of what quantity matter the universe holds, and though we do not understand exactly what it’s, we have a tendency to do comprehend it is plagued by gravity. The key, then, to understanding the ultimate fate of the Universe lies in understanding the opposite half this dark equation: dark energy.
Currently, cosmologists perceive nearly nothing regarding dark energy albeit it seems to comprise regarding seventy % of the mass-energy content of the universe. they’re urgently seeking to uncover its elementary properties: its strength, its permanency, and any variation with direction. they need to learn the properties of matter before they will verify its influence on the increasing Universe.
This evolution in cosmic scale is schematically shown within the higher than the figure for many cosmologies. during a universe with a high density of matter, the Edwin Bubble growth that began with the large Bang continues to decelerate thanks to the gravitation attraction of the matter filling the universe, ending during a massive crunch. during a universe with a lower vital density of matter, the growth coasts. during a universe with dark energy additionally as matter, the initial slowing is reversed at late times by the increasing dominance of dark energy.
If the hypothetic dark energy continues to dominate the universe’s energy balance, then the present growth of house can still accelerate, exponentially. Structures that don’t seem to be already gravitationally certain can ultimately fly apart. the planet and therefore the Milky Way Galaxy would stay undisturbed whereas the remainder of the universe seems to run far from the USA. The nature of dark energy is presently a matter of speculation. Some believe that dark energy could be “vacuum energy,” diagrammatic by the “cosmological constant” (Λ, the Greek capital letter lambda) normally relativity theory, a relentless uniform density of dark energy throughout all of the house that’s freelance of your time or the universe’s growth. This notion was introduced by Einstein and is according to our restricted observations so far. instead, dark energy would possibly vary with time. solely new sorts of observations will settle the difficulty.
We do understand this: Since the area is everyplace, this dark energy force is everyplace, and its effects increase as area expands. In distinction, gravity’s force is stronger once things area unit close and weaker after they area unit so much apart. as a result of gravity is weakening with the enlargement of area, dark energy currently makes up over 2/3 of all the energy within the universe. It sounds rather strange that we’ve got no firm plan regarding what makes up seventy-four of the universe. It’s as if we have a tendency to had explored all the land on the world Earth associate degreed ne’er all told our travels encountered an ocean. however currently that we’ve caught sight of the waves, we wish to grasp what this immense, strange, powerful entity extremely is.
The strangeness of dark energy is thrilling.
It shows scientists that there’s a spot in our information that must be crammed, beckoning the manner toward associate degree undiscovered realm of physics. we’ve got before the United States the proof that the cosmos could also be organized immensely otherwise than we have a tendency to imagine. Dark energy each signals that we have a tendency to still have a good deal to find out, and shows the United States that we have a tendency to stand poised for an additional nice leap in our understanding of the universe.
February 5, 2019(updated May 27, 2019) Published by Kshitij Kumar
How will the universe end, and could anything survive?
The universe serves up spectacle after spectacle with so much ease and effortlessness that you cannot help but wonder how it has so many complexities hidden within its ulterior cloak of beauty. On the surface, the universe is magnificent and splendid. The immortal souls that are credited for creating it are not yet finished with it. Perhaps, they get lost in its admiration and in its beauty and lose track of the job at hand. The fact that the universe can be so alluring despite its intricacies is in itself worth cherishing. But, like all good things, the universe will come to an end.
The end of the universe is not near, however, it is inevitable. There might not be any need to set alarm bells ringing anytime in the near future, but, the universe does have an expiration date.There have been several theories on how the universe could end. If the universe has been a cause for fascination and you want to learn more about how it could potentially all end, then, this article is just for you. Read on.
Let’s start from the beginning, the Origin of the Universe
To predict an ending, you would have to understand the beginning. Like all spectacular things, the universe too had a spectacular origin. This beginning was the Big Bang. The Big Bang theory explains the evolution that the universe had to undergo. This theory states that the universe was initially extremely hot and dense.As time passed, the universe began to cool and expand.
Image Source: Coldcreation
According to the Standard model, the four fundamental forces in the universe are gravity, strong and weak attractive forces and electromagnetic radiation. Of the four, gravity is considered to be the weakest. It is hypothesized that during the beginning of the universe that gravity was as strong as the other fundamental forces. All the matter in the universe was condensed into such small spaces that the gravity had to be extremely high. The universe did not stay in this condensed state for too long and began to expand. The expansion is considered to be perpetual and is taking place even while you are reading this.
What is really scary is the fact that the rate of this expansion keeps increasing every second. This expansion is credited to dark energy, but, nobody really knows for sure what it is. Here are the theories that try to explain how the universe could end.
The Big Rip
For as long as we have known, the universe has been expanding. During this process of expansion, lots and lots of space was created. Galaxies began to move apart since the space between them increased. Within the galaxy, the space also expanded. However, the gravity acted as the glue that kept it all together. The gravity provides the force that keeps the galaxies together. It is strong enough to negate the expansion. In the Big Rip scenario, the rate of expansion increases so drastically that it reaches a point where gravity cannot counter or negate the effect of the expansion of space. The acceleration of space expansion would be tremendously high.This causes the universe to, well, rip. This is what is referred to as the Big Rip.
This effect would start with the larger bodies and slowly propagate to the smaller bodies. It would first start with the galaxies. These galaxies would get ripped apart. Then, black holes, stars, and planets would die. Since the gravity is not strong enough, they would simply just dissolve into their constituents. Then these smaller components would disintegrate. Everything we know would get ripped apart.
Space would then start expanding so fast that it would be faster than even light! Atoms and subatomic particles would also tear apart. Since space is moving so fast, there would be no interaction between particles. So, even the small particles that remain after this massive expansion cannot interact with anything in the universe to form bigger particles. This universe would be so strange that when you compare it with today’s universe, it would seem ridiculous.The possibility is unfathomable, but, not impossible.
The Big Freeze
Simply put, the difference between the Big Freeze and the Big Rip is that in the Big Freeze scenario, matter does not disintegrate, it gets converted into radiation in a process that could take forever. To understand this, you will need to understand entropy. The second law of thermodynamics states that the entropy of an isolated system can never decrease, therefore, every body moves to a state which increases its entropy. This means that every body cools down and it disintegrates until it reaches some form of equilibrium. This is true for the universe as well. The matter in the universe slowly disintegrates and spreads out. Every body, whether big or small, will have its matter disintegrating into radiation.
The gas clouds required to generate stars would disintegrate. The universe will become an extremely dark place as a result. The suns would also disintegrate. Black holes would be the only entities left in the universe. These black holes, however, will also lose energy in the form of Hawking radiation and also disintegrate. Slowly but almost surely, only a few light particles would remain. But, even these will eventually decay. The universe would be reduced to nothing. A place of nothingness. Entropy would have reached its maximum, and the highest form of equilibrium would have been reached. The universe would have finally ended.
However, all hope is not lost. The phenomenon of quantum tunneling could cause a change in the entropy leading to another Big Bang. In this case, the universe would just restart as if nothing really happened.
The Big Crunch and The Big Bounce
Gravity, which is the weakest of all fundamental forces could one day become the most powerful. This is possible if the amount of dark energy reduces substantially over time. This would mean that the universe would simply stop expanding. This would mean that the rate of expansion would slow down at some point and keep slowing down until the process of expansion ceases. Then, it slows down even more and reverses. The universe, instead of growing, would begin to contract and become smaller and smaller. Galaxies will merge, and the universe will get significantly hotter. The temperatures would reach such high levels that bodies that cannot bear such temperatures would disintegrate. Everything will get denser.
Big Crunch Illustration. Image Source : Wikipedia
Black holes that consume everything close to them, would begin consuming bodies. As things get closer and closer, more objects would get closer to black holes. These black holes would consume everything including other black holes. The amount of gravity will be immense. All black holes will eventually form a single supermassive blackhole at the center of the universe. At the last moment of the Big Crunch, the entire universe would be consumed by the gigantic black hole and finally, it would consume itself. The Big Bounce theory states that this entire process has been taking place for a long while. According to the Big Crunch, the universe is stuck in a loop of expansion and contraction leading to many deaths and rebirths of the universe.
The timeline for the end of the universe
Our planet will cease to exist in about 1 billion years from now. The Sun would burn 10% brighter and the heat from the sun would dry up all the water on earth. All life will be extinguished. In about 5 to 8 billion years, the sun would undergo expansion to reach a size that is so big that it would devour most planets. In about 1 trillion years from now, all galaxies would merge into one. In 100 trillion years, we would enter the degenerate era. This era is marked by the death of all stars in the galaxies, which, results in black holes. In 10 to 100 quintillion years, everything would be consumed by black holes. In a decillion years time, we might have the black hole era, where the universe is dominated by black holes. Eventually, these black holes will lose energy in the form of Hawking radiation and die too. In about a googol year, the universe would cease to exist.
Erich Fromm, a renowned psychologist, and sociologist once said, “The quest for certainty blocks the search for meaning. Uncertainty is the very condition to impel man to unfold his powers”. There is so much uncertainty around. Everything in the universe is uncertain, so much so that even the universe itself is uncertain! The universe always has a clever way to teach important lessons. Uncertainty should compel humanity to make the most of the time we have.
The universe can die but it can start all over again. The reality that we observe today may not be considered reality at all in the distant future. Whether the universe ends or not, one thing is certain, the universe should be cherished and celebrated while we can all still bask in its splendor.
February 4, 2019(updated July 13, 2019) Published by Kshitij Kumar
Black Holes: Discovery, Facts and Theories
A Black hole has always been a thing of immense wonder. Even the most fervent scientists have been unable to fully understand a black hole. A part of its magnificence probably lies in the fact that it still has certain mysteries associated with it. The more you find out about black holes, the more mesmerized you become. So, if you are looking to learn about black holes and possess a desire to try and understand them better, then, stick around, this article is just for you.
According to Wikipedia “A black hole is a region of spacetime exhibiting gravitational acceleration so strong that nothing—no particles or even electromagnetic radiation such as light—can escape from it“. Most black holes are created when stars implode. The gravity at the centre of the star reaches such high values that the star can no longer sustain the reactions that take place at its core. This implosion gives rise to a body of immensely high gravitational pull, called the black hole. These black holes are said to have an extremely high gravitational pull, which, led to the notion that black holes suck in everything around them. Albert Einstein has been credited for predicting the existence of black holes through his general theory of relativity. However, the term ‘black hole’ was coined by John Wheeler.
Creation of black holes
Cygnus X-1 (the image is an artist’s impression). Image Source: Sun.org
So, how are black holes formed? So, we all know that there are trillions of stars out there in the universe and all these stars continuously undergo fission reaction to keep shining. But, there comes a point when the star has very little fuel to burn out or the star gets receives extra matter in a way that does not raise its core temperature, in both these cases the star collapses. If the mass of the collapsing star is greater than a threshold then it will form a black hole. These black holes are called stellar black holes. The said threshold is called the Tolman–Oppenheimer–Volkoff limit which is 3-4 solar masses(M☉)
M☉ = (1.98847±0.00007)×1030 kg
This is not the only way by which black holes can form. Black holes can also form by high energy collisions which can achieve sufficient density. However, till now we didn’t detect any such events directly or indirectly probably because of mass-imbalance in particle accelerators. Thus, scientists came to the conclusion that there might be some lower boundary of mass for black holes to form and that would lie around Planck mass.
Planck mass = mP=√ħ c/G ≈ 1.2×1019 GeV/c2 ≈ 2.2×10−8 kg
ħ is the Planck’s constant
c is the speed of light
G is the universal gravitation constant
e is the charge of an electron
V is 1 volt
eV/c2 is commonly used to express mass in particle physics
The outer visible part of the black hole is referred to as the event horizon. In other words, the event horizon is the boundary of the black hole. The innermost part of the black hole is, what scientists call, the singularity. The constituents of a black hole are not quite known to even the most ardent scientists who study black holes.
The death of black holes
Black holes do not last forever either. In an excruciatingly slow process, black holes emanate energy and become hotter and hotter. Black holes, in this process, begin to grow smaller and smaller. They eventually disintegrate in a massive and spectacular manner, with an explosion. This entire process is attributed to the empty space around the black hole. This disintegration is often referred to as black hole evaporation.
You might have heard that the empty space is not actually empty. This is true, empty space consists of virtual particles that randomly come into existence and cancel each other out every now and then. The pair of particles that cancel each other out, is generally referred to as, the particle-antiparticle pair. When this process takes place at the event horizon of the black hole, some particles enter the black hole, while others escape outwards into space.
This results in the loss of energy of the black hole. This loss causes the black hole to become smaller. Initially, this process is slow, but, it soon picks up the pace and becomes faster. This radiation of energy by the black hole is called the Hawking radiation, named after probably one of the most renowned physicists of the recent past, Dr Stephen Hawking.
This flow chart shows the life cycle of stars from birth to remnant stages. Image Source: Wikipedia
What’s inside a black hole?
To be honest, nobody really knows for sure. It is highly unlikely that you would find someone on the face of the earth who could tell you with a great deal of certainty, what exists inside a black hole. The black hole, due to its immense gravitational pull, does tend to pull most entities that are present in its proximity. However, the belief that it attracts particles and bodies towards it, is a misconception. A black hole does not attract entities towards itself, it merely consumes the bodies that are already close to it. That is, if an entity is far away from the black hole, the black hole would not cause the entity to move closer towards the black hole, however, if the entity were in the devouring range of the black hole, it would inadvertently get sucked in.
Nothing is said to escape from the black hole. Even light can’t escape its clutches. To escape from the inside of a black hole, it is said that you would have to be travelling at speeds greater than the speed of light which is not possible according to Einstein’s theories. It is believed that most of the mass of the black hole is concentrated at its centre. This part of the black hole where the mass is said to accumulate is called the singularity.
To figure out what actually is inside a black hole, we would have to send something into it. The problem with this is that anything that enters the black hole cannot return from it. It is highly likely that we will never find out what actually is inside of a black hole.
If you have ever thought to yourself that it would be fascinating to enter a black hole and have ever considered going into one, you should probably reconsider. The larger the black hole, the more intact you are likely to be when you enter, but, there does not exist a black hole that would not kill you as soon as you reach the event horizon. You would get spread, elongated and ripped apart in what is known as spaghettification. Spaghettification is the process in which objects are ripped apart due to the strong gravitational pull of the black hole.
Types of black holes
Blackholes are considered to be of three main types, based on their mass. They are
Stellar black holes
Supermassive black holes
Miniature black holes.
Stellar black holes are those that are formed by the collapsing of the stars. The exact process of formation of stellar black holes is mentioned above The masses of these black holes generally range from 5 to several times the mass of the sun.
Supermassive black holes, on the other hand, have masses that are several hundred or thousands of times the mass of the sun. It is hypothesized that every galaxy in the universe has a supermassive black hole at its centre. Sagittarius A is the black hole considered to be at the centre of the Milky Way. Some scientists also believe that these supermassive black holes have existed since the creation of the universe, or at least, since the creation of each galaxy.
Miniature black holes, as the name suggests, possess the smallest mass of all black holes. There was a time when physicists and astronomers believed that the stellar black hole was the smallest form of black holes. Stephen Hawking introduced the concept that there might exist black holes smaller than the mass of the stellar black hole. These are said to be primordial black holes. Primordial black holes are those that have existed since the Big Bang. These are speculated to have been formed due to the fluctuations in the density of the universe. Theoretically, anything that can have its mass densely condensed and possess an escape velocity greater than the speed of light can become a black hole but experimentally a black hole can possess any mass equal to or greater than the Planck mass.
Scientists are now planning to get improved pictures of black holes. Let us hope that uncover the secrets of cosmos and answer some questions which have been daunting scientists from centuries
Neil Armstrong, widely renowned for being the first man to step on the moon, once said, “Mystery creates wonder and wonder is the basis of man’s desire to understand”. Perhaps, there exists no phenomenon in the world that epitomizes the saying more than a black hole does. Black holes are incredibly fascinating and are surrounded with so much mystery that one cannot help but be enamoured by it. However, black holes are quite dangerous, nonetheless. If one were to travel anywhere close to one, they would be sucked into it with no point of return. In all honesty, it would be truly amazing to venture into a black hole to find out what it consists of, but, it most certainly is not worth the risk. A simile that best sums up the situation goes something like
February 4, 2019(updated August 24, 2019) Published by Kshitij Kumar
Astronomers calculated that the Big Bang occurred between twelve and fourteen billion years ago. To place this in perspective, the solar system is assumed to be 4.5 billion years old and humans have existed for a few million years.
Astronomers estimate the age of the universe in 2 ways:
By trying to find the oldest stars
By finding out the speed of expansion of the universe and extrapolating back to the Big Bang
Is it older than the stars?
Astronomers could place a lower limit to the age of the universe by studying about Globular clusters. These circular clusters are a dense assortment of roughly 1,000,000 stars. Stellar densities close to the middle of these clusters are huge. If we lived close to the middle of one, there would be several hundred thousand stars closer to us than the Proxima Centauri, the nearest star after the Sun.
The life cycle of a star is solely depended upon its mass. High Mass stars are a lot brighter than Low Mass stars; therefore they quickly burn through their supply of hydrogen fuel. A star just like the Sun has enough fuel in its core to burn at its current brightness for roughly nine billion years. A star that is twice as massive as the Sun will burn through its fuel supply in only 800 million years. A 10 solar mass star, a star that is 10 times more massive than the Sun, burns nearly a thousand times brighter and has only a 20 million year fuel supply. Conversely, a star that is half as massive as the Sun burns slowly enough for its fuel to last more than 20 billion years.
All the stars in a globular cluster are formed roughly at the same time; therefore they function like cosmic clocks. If a cluster is over twenty million years old, then all of its hydrogen-burning stars will be less massive than 10 solar masses. This suggests that no hydrogen-burning star is going to be over a thousand times brighter than the Sun. If a cluster is over two billion years old, then there’ll be no hydrogen-burning star more massive than 2 solar masses.
The oldest cluster contains only those stars which are less massive than 0.7 solar masses. Low Mass stars are a lot less dim than the Sun. This observation suggests that the oldest clusters are between 11 and 14 billion years old. The uncertainty in this estimate is because of the problem in finding the precise distance to cluster (hence, uncertainty within the brightness (and mass) of the stars in the cluster). Another source of uncertainty during this estimate lies in our ignorance of finer details of stellar evolution.
Astronomers also study some old stars and try to detect remaining dust from ancient supernova to have some more limits to the age of the universe.
However, there are some stars found which contradicts the currently believed age of 13.8 billion years. Read about one such star called HD 140283 here
An alternative approach to estimate the age of the universe is to calculate the “Hubble constant”. The Hubble constant is a measure of the expansion rate of the universe. Cosmologists use this activity to extrapolate back to the Big Bang. This extrapolation depends on the history of the expansion rate that depends on the present density of the universe and on the composition of the universe.
If the universe is flat and composed largely of matter, then the age of the universe is
where Ho denotes the Hubble’s constant.
If the universe has a very low density of matter, then its extrapolated age is larger:
If the universe contains a form of matter similar to the cosmological constant, then the inferred age can be even larger.
Many astronomers are operating exhaustingly to calculate the Hubble’s constant employing a type of completely different techniques. Till recently, the simplest estimates ranged from 65 km/sec/Megaparsec to 80 km/sec/Megaparsec. In additional acquainted units, astronomers believe that 1/Ho is between 12 and 14 billion years.
In the latest researches, the results have been shown that the universe is enlarging much quicker than it should be based on the conditions after Big Bang. The constantly increasing rate of the universe is known as Hubble Constant and it has been very hard to pin down the rate.
AN AGE CRISIS?
On comparing the two age determinations, there is a potential crisis. If the universe is flat and dominated by ordinary or dark matter, the age of the universe as estimated from the Hubble constant would be around 9 billion years. This would lead to a contradiction as the age of the universe would be shorter than the age of oldest stars. This contradiction implies that either
Our measurement of the Hubble constant itself is incorrect
The Big Bang theory has to be replaced
That we need a form of matter like a cosmological constant that implies an older age for a given observed expansion rate.
Some astronomers believe that this crisis will pass as soon as measurements improve. If the astronomers who have measured the smaller values of the Hubble constant are correct, and if the smaller estimates of globular cluster ages are also correct, then all is well for the Big Bang theory, even without a cosmological constant.
Measurements by the WMAP (Wilkinson Microwave Anisotropy Probe) satellite facilitated and confirmed the age of the universe. By measuring the thermal radiation left over from the Big Bang(known as Cosmic Microwave Background), missions such as WMAP are able to determine the density, composition and expansion rate of the universe. As of 2013, WMAP determined these parameters with an accuracy of higher than 1.5%. In turn, knowing the composition with this precision, we could estimate the age of the universe to about 0.4%: 13.77 ± 0.059 billion years!
WMAP satellite artist depiction. Image Source: NASA
How does WMAP data enable us to determine the age of the universe is 13.77 billion years, with an uncertainty of only 0.4%? The key to this is that by knowing the composition of matter and energy density in the universe, we will use Einstein’s theory of relativity to calculate how fast the universe has been expanding in the past. With this information, we will flip the clock back and estimate when the universe had “zero” size, in line with Einstein.
The time between then and now could be the age of the universe. There’s one caveat to keep in mind that affects the understanding of the age determination: we have a tendency to assume that the universe is flat, that is well supported by WMAP and alternative knowledge. If we relax this assumption, the uncertainty will increase. Inflation naturally predicts a really nearly flat universe.
The expansion age measured by WMAP is larger than the oldest globular clusters, so, Big Bang theory has passed a crucial test using data independent of the type collected by WMAP. If the expansion age measured by WMAP had been smaller than the oldest globular clusters, then there would be something wrong in either the Big Bang theory or the theory of stellar evolution. Either way, astronomers would have required rethinking several of their cherished concepts. However, our current estimate of age fits well with what we all know from other forms of measurements.
So, in conclusion, we’ve 2 methods — one from our cosmic history and one by measuring native stars — that show us our Universe’s age is between thirteen and fourteen billion years. Today it is widely accepted that our universe in 13.772 billion years old with a possible error of 59 million years. However, there are a lot of observations and experiments going on to get more precise age of our universe
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