Time Travel: Theories, Paradoxes & Possibilities
We all travel in time, don’t we? During 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 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 it science fiction or is it truly possible?
Physics behind time travel
The great scientist Albert Einstein stated extensive theories on Special Relativity. Special Relativity is a difficult concept to grasp upon but it’s confirmed by scientists that we do experience it in our everyday lives. According to this theory, space and time are two sides of the same coin. Light always maintains the same speed limit through space that is 300,000 kilometers per second.
An interesting thing happens when our speed relative to other objects is close to the speed of light. Time actually starts going slower for us than for the people around us. But we won’t notice this effect until we return to those stationary around us. Mind-boggling, isn’t it?
Let’s take an example. Suppose we were 15 years old when we left Earth in a spacecraft travelling at about 99.5% of the speed of light(which has not been achieved yet), and we only celebrated 5 birthdays during our space voyage. By the time we get home when we are 20 years old, we would sadly find all our friends to be 65 years old! Most probably retired and relaxing with their grandchildren. This bizarre event is actually theoretically accurate. This is because time passed slowly for us as compared to our friends hence we experienced only five years in comparison to them experiencing 50 years.
Among Einstein’s many theories, here’s a remarkable one called General Relativity. According to this theory, time passes more slowly for objects in gravitational fields than for objects in other fields. Hence, in black holes, where gravity is extremely intense, there occur all times of space-time distortions.
In his memoirs, Einstein wrote that he was disturbed that his equations contained solutions that allowed for time travel.
But he finally concluded: the universe doesn’t rotate; it expands (i.e.as within the detonation theory) and therefore Godel’s resolution might be thrown out for “physical reasons.” (Apparently, if the Big Bang was rotating, then time travel would be possible throughout the universe!)
Godel’s resolution stated of a universe filled with a rotating field. Anyone walking along the direction of the rotation would find themselves back to where they started.
Then in 1963, Roy Kerr, a mathematician, found a solution of Einstein’s equations for a rotating black hole, which had bizarre properties.
The black hole wouldn’t collapse to a degree (as antecedently thought) however into a spinning ring (of neutrons).
The ring would be therefore rotating so fast that the force would keep the ring from collapsing beneath gravity.
The ring, in turn, acts just like the looking glass of Alice.
Anyone walking through the ring wouldn’t die, however, might end up through the ring into an alternate universe.
Since then, many different “wormhole” solutions are found to Einstein’s equations.
These wormholes connect not solely 2 regions of a house (hence the name) however additionally 2 regions of your time likewise.
In principle, they will be used as time machines.
Attempts to add to the quantum theory are going on every moment targeting to achieve the “Theory of Everything”. Since in quantum theory there can be two states of the same object, so by going back in time and changing the past, we are only creating a parallel universe.
The river of time forks into two different tributaries.
But this doesn’t solve all problems. Rather creates more.
First, the main problem is one of energy.
In the same means that an automobile wants fuel, a machine has to have fabulous amounts of energy.
One either needs to harness the facility of a star or to search out one thing known as“exotic” matter (which falls up, instead of down) or notice a supply of negative energy.
(Physicists once thought that negative energy was impossible.
But small amounts of negative energy are through an experiment verified for one thing known as the Casimir impact, i.e.the energy created by two parallel plates).
All of those are passing tough to get in massive quantities, a minimum of for many additional centuries!
Is time travel possible?
The BBC’s long-running science-fiction series Doctor Who, celebrating its fiftieth day of remembrance on twenty-three Nov, centers 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 Einstein’s theory of relativity, developed in 1905, shows that point passes at totally different rates for those who area unit moving relative to 1 another – through the impact solely becomes massive once you get near to the speed of sunshine.
If one were to go away from Earth inside an artificial satellite moving at a considerable fraction of light, speed, rotate and are available back, solely a number of years may need to be passed on board however a few years may have gone along on Earth. This can be referred to as the “twins paradox” since an individual enterprise such a journey would come to search out herself a lot of younger than her twin.
There’s just one drawback from anyone want to induce a glimpse of the longer term – obtaining back. It might mean move quicker than light-weight – and that’s unattainable.
But there could also be associate dead set be found generally Einstein’s theory of relativity, Einstein’s theory of gravity that unites house and time as “space-time”, that curves within the presence of mass. It permits for the likelihood of wormholes – a form of a tunnel through space time connecting otherwise terribly distant components of the universe.
If the “mouths” of the whole area unit moving relative to 1 another, then traversing the bridge between totally different purposes in a house would additionally take an individual to a special point in time thereto during which she started.
However, it might still be not possible to travel back any in time than the purpose at that the hole was created, limiting the choices for travel somewhat – and presumably explaining why we tend to haven’t encountered any guests from the longer term. If any natural wormholes were fashioned within the detonation, it’d be attainable to travel a restricted variety of points within the past and within the distant universe, however, wouldn’t alter one to flit around the cosmos.
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 granddad before one’s father is planned – preventing one’s own birth, creating it not possible to travel back in time and kill one’s granddad. Thorne found that for purpose lots traversing a hole, no initial conditions produce this kind of contradiction in terms.
That’s excellent news for anyone troubled concerning folks going back and ever-changing the past at random, however unhealthy news for any Whoever hoping to reverse the choice to cancel the show in 1989 and forestall a 16-year hiatus. That willing all probability be on the far side even the Doctor himself.
Fun facts about time-travel
- The fourth dimension
Simply expressed, the primary 3 dimensions are accustomed to specifying associate degree object’s location/movement in an area (forward-backwards, left-right and up-down), whereas the time locates its position in time. All four dimensions are accustomed to specifying utterly the placement or dynamism of associate degree object in an area. together the four dimensions are inseparably interlinked and referred to as a reference frame.
- Third dimension beings
Being 3-dimensional creatures (possessing length, breadth and height), humans area unit unable to envision the dimension as our physical world is made among these 3physical dimensions. we would feel or compass time’s presence, however, we are able to ne’er truly observe it with our three-dimensional senses as a result of it extends on the far side our universe. Humans solely understand the dimension time as recollections lodged at variable intervals, the results of that are our apparent perception of your time moving forward during a line. However, time still exists as a dimension and objects will cross it during a similar means as they are doing the others, though 3 dimensional like humans will solely move in one direction forward through time. If we tend to might see associate degree object’s fourth-dimensional frame of reference (or world-line) it should check a spaghetti-like line stretching from the past to the long run showing the spatial location of the item at each instant in time.
- 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 travelers can at least experience it vicariously through movies, television and books.