Can we travel back in time and change the sequence of events or we can just view events occurred in past?

Question

We know that objects are visible to us are due to reflection of light from the object which our eyes comprehend .Now my question is if we travel with a speed higher than speed of light then is it possible to view objects which were there or events which occurred inpast respectively?

Answer 1

Time travel to the past
Time travel to the past is theoretically allowed using the following methods[4]:

Traveling faster than the speed of light
Curved spacetime
The use of cosmic strings and black holes
Wormholes and Warp drive

The equivalence of time travel and faster-than-light travel
If one were able to move information or matter from one point to another faster than light, then according to special relativity, there would be an observer who sees this transfer as allowing information or matter to travel into the past. Additionally, faster than light travel along suitable paths would correspond to travel backward in time as seen by all observers. This results simply from the geometry of spacetime and the role of the speed of light in that geometry. However, traveling faster than light bends the laws of physics and is currently believed to be impossible

Special spacetime geometries
The general theory of relativity extends the special theory to cover gravity, illustrating it in terms of curvature in spacetime caused by mass-energy and the flow of momentum. General relativity describes the universe under a system of "field equations," and there exist solutions to these equations that permit what are called "closed time-like curves," and hence time travel into the past. This theory can be supported by the fact that any object that moves slower than light is propelled forward in time. [2]The first and most famous of these was proposed by Kurt Gödel, but his (and many others') examples require the universe to have physical characteristics that it does not appear to have.[2] Whether general relativity forbids closed time-like curves for all realistic conditions is unknown.

Using wormholes :-The idea of warping space to travel to the past is more plausible than traveling faster than the speed of light because it does not break the laws of Einstein's relativity[5]. Wormholes are a way of warping space. A proposed time-travel machine using a wormhole would (hypothetically) work something like this: A wormhole is created somehow. One end of the wormhole is accelerated to nearly the speed of light, perhaps with an advanced spaceship, and then brought back to the point of origin. Due to time dilation, the accelerated end of the wormhole has now experienced less subjective passage of time than the stationary end. An object that goes into the stationary end would come out of the other end in the past relative to the time when it enters. One significant limitation of such a time machine is that it is only possible to go as far back in time as the initial creation of the machine[6]; in essence, it is more of a path through time than it is a device that itself moves through time, and it would not allow the technology itself to be moved backwards in time. This could provide an alternative explanation for Hawking's observation: a time machine will be built someday, but has not yet been built, so the tourists from the future cannot reach this far back in time.

According to current theories on the nature of wormholes, creating a wormhole of a size useful for a person or spacecraft, keeping it stable, and moving one end of it around would require significant energy, many orders of magnitude more than the Sun can produce in its lifetime. Construction of a wormhole would also require the existence of a substance known as "exotic matter", which, while not known to be impossible, is also not known to exist in forms useful for wormhole construction (but see for example the Casimir effect). Therefore it is unlikely such a device will ever be constructed, even with highly advanced technology. On the other hand, microscopic wormholes could still be useful for sending information back in time.

In 1993, Matt Visser argued that the two mouths of a wormhole with such an induced clock difference could not be brought together without inducing quantum field and gravitational effects that would either make the wormhole collapse or the two mouths repel each other. [7] Because of this, the two mouths could not be brought close enough for causality violation to take place. However, in a 1997 paper, Visser hypothesized that a complex "Roman ring" (named after Tom Roman) configuration of an N number of wormholes arranged in a symmetric polygon could still act as a time machine, although he concludes that this is more likely than not a flaw in classical quantum gravity theory rather than proof that causality violation is possible. [8]

Another approach — attributed to Frank Tipler, [9] but invented independently by Willem Jacob van Stockum [10] in 1936 and Kornel Lanczos [11] in 1924 — involves a spinning cylinder. If a cylinder is long, and dense, and spins fast enough about its long axis, then a spaceship flying around the cylinder on a spiral path could travel back in time (or forward, depending on the direction of its spiral). However, the density and speed required is so great that ordinary matter is not strong enough to construct it. A similar device might be built from a cosmic string, but none are known to exist, and it does not seem to be possible to create a new cosmic string.

Physicist Robert Forward noted that a naïve application of general relativity to quantum mechanics suggests another way to build a time machine. A heavy atomic nucleus in a strong magnetic field would elongate into a cylinder, whose density and "spin" are enough to build a time machine. Gamma rays projected at it might allow information (not matter) to be sent back in time. However, he pointed out that until we have a single theory combining relativity and quantum mechanics, we will have no idea whether such speculations are nonsense.
Time travel and the anthropic principle
It has been suggested by physicists such as Max Tegmark that the absence of time travel and the existence of causality may be due to the anthropic principle. The argument is that a universe which allows for time travel and closed time-like loops is one in which intelligence could not evolve because it would be impossible for a being to sort events into a past and future or to make predictions or comprehend the world around them (at least, not if the time travel occurs in such a way that it disrupts that evolutionary process).

Answer 2

"We know that objects are visible to us are due to reflection of light from the object which our eyes comprehend."

You can definitely see objects or events from the past but you can't change the sequence. This is like a video (captured light). Changing the video doesn't change the actual object or event.

Answer 3

Well, general relativaty states that as you approach the speed of light, time slows down. The logical extreme of that is that if you go faster than that, time starts going backwards.

So if you say something stupid, you could just run around in circles for a little bit (assuming you can run faster than the speed of light), go back in time and stop yourself saying it. Which I guess translates to a yes to your question.

Several practical problems present themselves. The major one is that as you approach the speed of light, you gain mass, which means that you need more and more force to keep you accelerating. To get over the speed of light you need an infinite force, and it doesn't matter how many push ups you do, you'll never be able to exert that much force.

Answer 4

The rays of light coming from distant stars has travelled millions of light years before it reach our eyes. By the time it reach, the star would not be there as it would have moved w.r.t its galaxy or it would have died out. The light which we recieve is nothing but light emitted in the past.
So what we see is the past event of the star in the present. We need not travel back in time to see that, we can see it in present real time itself.

Answer 5

The speed of light can and has been broken.
You can travel backwards in time via a casimer effect created wormhole being transported near the speed of light (the entry point) and one stationed at the (exit point) desired destination.

Answer 6

first thing is how u go to past and by some how if u make it than the latest theory say that u can change it but the world u r living that time is not the one u come from it is the parallel universe(a very new concept which state that their are several universe which r distinct but running parallel.

Answer 7

WELL IT WILL NOT BE POSSIBLE BECAUSE IF WE EVEN ASSUME THAT WE ARE TRAVELLING FASTER THAN LIGHT THEN ALSO THE SPEED OF LIGHT WILL BE CONSTANT AND EVERYTHING YOU SEE WILL TAKE THE SAME TIME TO REACH YOUR EYES, AND HENCE ONLY THING YOU WOULD CHANGE IS YOUR SPEED, NOTING ELSE

Answer 8

The past only exists in your memory. No matter how fast you travel, you will only be able to see light particles in their current location and time will have passed by the time you get there.

Perhaps, if you underwent hypnosis, you could revisit the past and rearrange it in your mind.

Answer 9

Nope, it is not possible. Yet. But hen, neither would it be possible in the future because if the people in the future sees the people in the past(not on a video but live) then we would see them also, and we don't see anyone from the future coming to us now.

Answer 10

We can't travel faster than light unless we find an omnipotent power source.

Answer 11

Well, the law says you CAN'T travel faster than the speed of light, so this question is moot and Unanswerable