Do you think time travel could ever happen or has already happened?

Question

O.K. say you went back in time. Wouldn't everything you do somehow effect the timeline. What if whatever you did in the past changed the timeline so much that in the future you never really went back in time. How could time travel ever be possible? I don't think it could, could it? Any other opinions?

Answer 1

Everytime you look at a star the light that allows you to see that star has travelled millions (at least) of miles for many years, you are looking at something that might even no longer exist. In that sense you are observing time travel every night when you look at stars as that you are observing the past.

Anti-matter which is only theoretical in quantum physics is defined as travelling backwards in time.

Time travel may in theory be possible with the idea of wormholes (which would also eliminate the speed of  light barrier problem).  Michio Kaku of the City University of New York has done some work on this issue.

Michael John Weaver, M.S.

Answer 2

the three laws of time travel.

I) everything you do in the past affects the future

II) the further back you go in the past the greater the future affects are.

III) Time travel into the future is impossible

Keeping track of all the different possibilities though would take superpowerful computers

A society so advanced as to have time travel would be smart enough as to work in secret as to keep any future affects under control.  

Early time travel would have a limit though In the early days of t.t. you would be limited by reverse aging  but after some time a way to move past that limit would be invented .

Answer 3

I don't think we can rule it in or out. We don't have the scientific information, right now, to  make an educated guess. The possibility of time traveling (into the past or into the future) is a fascinating idea.

Answer 4

Paradox explains why time travel has not, nor will ever happen.

Answer 5

Time travel is possible in the context of time dilation. In this theory one may travel into the future but never into the past.

In Albert Einstein's theories of relativity time dilation is manifested in two circumstances: In special relativity, clocks that are moving with respect to an inertial system of observation (the putatively stationary observer) are found to be running slower.

This effect is described precisely by the Lorentz transformation. In general relativity, clocks at lower potentials in a gravitational field — such as in close proximity to a planet — are found to be running slower. In special relativity, the time dilation effect is reciprocal: as observed from the point of view of any two clocks which are in motion with respect to each other, it will be the other party's clocks that is time dilated.

Thus the duration of the clock cycle of a moving clock is found to be increased: it is measured to be "running slow." The range of such variances in ordinary life, where v / c < 1 even considering space travel, are not great enough to produce easily detectable time dilation effects, and such vanishingly small effects can be safely ignored. It is only when an object approaches speeds on the order of 30,000 km/s (1/10 of the speed of light) that time dilation becomes important.

Time dilation by the Lorentz factor was predicted by Joseph Larmor (1897). It has been tested a number of times. The routine work carried on in particle accelerators since the 1950s, such as those at CERN, is a continuously running test of the time dilation of special relativity. The specific experiments include:

Velocity time dilation tests:

Ives and Stilwell (1938, 1941), “An experimental study of the rate of a moving clock”, in two parts. The stated purpose of these experiments was to verify the time dilation effect, predicted by Lamor-Lorentz ether theory, due to motion through the ether using Einstein's suggestion that Doppler effect in canal rays would provide a suitable experiment. These experiments measured the Doppler shift of the radiation emitted from cathode rays, when viewed from directly in front and from directly behind. The high and low frequencies detected were not the classical values predicted.



Rossi and Hall (1941) compared the population of cosmic-ray produced muons at the top of a mountain to that observed at sea level. Although the travel time for the muons from the top of the mountain to the base is several muon half-lives, the muon sample at the base was only moderately reduced. This is explained by the time dilation attributed to their high speed relative to the experimenters. That is to say, the muons are decaying about 10 times slower than they would in a rest frame (that is, for "stationary observers").

Hasselkamp, Mondry, and Scharmann (1979) measured the Doppler shift from a source moving at right angles to the line of sight (the transverse Doppler shift) as deduced by Einstein (1905). Thus there is no transverse Doppler shift, and the lower frequency of the moving source can be attributed to the time dilation effect alone.

In contrast, gravitational time dilation (as treated in General Relativity) is not reciprocal: an observer at the top of a tower will observe that clocks at ground level tick slower, and observers on the ground will agree. Thus gravitational time dilation is agreed upon by all stationary observers, independent of their altitude.

Gravitational time dilation tests

Pound, Rebka in 1959 measured the very slight gravitational red shift in the frequency of light emitted at a lower height, where Earth's gravitational field is relatively more intense. The results were within 10% of the predictions of general relativity. Later Pound and Snider (in 1964) derived an even closer result of 1%. This effect is as predicted by gravitational time dilation.

Velocity and gravitational time dilation combined-effect tests:

Hafele and Keating, in 1971, flew cesium atomic clocks east and west around the Earth in commercial airliners, to compare the elapsed time against that of a clock that remained at the US Naval Observatory. Two opposite effects came in to play. The clocks were expected to age more quickly (show a larger elapsed time) than the reference clock, since they were in a higher (weaker) gravitational potential for most of the trip. But also, contrastingly, the moving clocks were expected to age more slowly because of the speed of their travel. The gravitational effect was the larger, and the clocks suffered a net gain in elapsed time. The net gain was consistent with the difference between the predicted gravitational gain and the predicted velocity time loss. In 2005, the National Physical Laboratory in the United Kingdom reported their limited replication of this experiment. The NPL experiment differed from the original in that the cesium clocks were sent on a shorter trip (London-Washingon D. C. return), but the clocks were more accurate. The reported results are within 4% of the predictions of relativity.

The Global Positioning System can be considered a continuously operating experiment in both special and general relativity. The in-orbit clocks are corrected for both special and general relativistic time-dilation effects so they run at the same (average) rate as clocks at the surface of the Earth. In addition, but not directly time-dilation related, general relativistic correction terms are built into the model of motion that the satellites broadcast to receivers.

Time dilation and space flight:

Time dilation would make it possible for passengers in a fast moving vehicle to travel further into the future while aging very little, in that their great speed retards the rate of passage of onboard time. That is, the ship's clock (and according to relativity, any human travelling with it) shows less elapsed time than stationary clocks. For sufficiently high speeds the effect is dramatic. For example, one year of travel might correspond to ten years at home..

A more likely use of this effect would be to enable humans to travel to nearby stars without spending their entire lives aboard the ship. However, any such application of time dilation would require the use of some new, advanced method of propulsion. A further problem with relativistic travel is that at such velocities dispersed particles in the rarefied interstellar medium would turn into a stream of high-energy cosmic rays that would destroy the ship unless extraordinary radiation protection measures were taken. Strong electromagnetic fields that could ionize and deflect any interstellar matter has been suggested as one way to avoid these potentially disastrous consequences.

Answer 6

According to Einstein, time is relative to the observed and the observer.

The Doppler effect is a perfect example of this.

As a train approaches, the sound is raised in pitch because the sound waves are compressed because of the speed of the moving train.  After the train passes, the sound is lowered in pitch because the sound waves are expanded by the movement of the train.

The same general thing happens as you approach the speed of light.  As you get faster and faster, everything appears to slow down.

The catch is, you can never have infinite mass.  The particles in the accellerators increase in mass the faster they travel, in a manner agreeing with Einstein.  They also decay slower, because of the speed they are travelling at. (Time, for the particles, has slowed, relative to the observer.)\

The only particle that may be able to travel in time are tachyons.  These are theoretical particles that can ONLY travel faster than light, and appear to be immune to the mass accumulation effect of the accelleration to the speed of light.

Answer 7

No, never happen.  It is all myth and sci fi.

Answer 8

It is not so much time travel as missing time.

your intention is fulfilled without the travel time in between.

It happens in small fragments almost not to be noticed.

Answer 9

No

Answer 10

Logic would suggest that if time travel were ever to exist, then it already does. If time travel is possible, then the methods required will eventually be devised. Maybe it will take another 10 thousand years to discover the secrets of time travel, but if it's possible, then it's inevitable. Which suggests that time travellers are already visiting us... and visiting our past.

Answer 11

Wow many good answers, Based on what we know now that is. Will it ever be possible maybe. We know we can go forward in time with what we have now in the labs.

There was a test with a laser in lab and it read that the laser hit split second before the button was pushed. ok granted was only like a milli second but still.

I say maybe because for the most part we still don't know our butts from a hole in the ground no matter how smart we think we are on the subject, its still in its infancy.  The ones disagree remember the world was flat at one point and all the scientist agreed then to, and they thought they knew the world.

Just my 2 cents. and not someone else's.

Answer 12

most probably not coz you have to travel faster than light to go back in time. travelling that fast is quite impossible.

Answer 13

it's happening right now. everyone it traveling through time at a speed of 24hr a day. If you want to travel back in time, then sip some coffee, relax and remember the good old days.

Answer 14

i doubt time travel will ever be possible

modern science dictates time travels only in one direction and scientists currently have no proof that time can ever be reversed.  

if time travel was possible, then surely we would have people from the future coming back in time and bringing with them scientific information that would put one country well ahead of its contemporary rivals, leaving that nation beyond any reasonable doubt, unchallenged by any competitors.  if that, really happened, then we'd have a long boring history class in high school about one country that kicks everyone's a**.  

something that DOES seem possible in regards to time though, is slowing it down.  there are many experiments that have been conducted which suggest and maybe even prove that it is possible to slow time down if one is traveling at speeds comparable to the speed of light.  one such experiment i have read about was where particles moving at VERY high speeds in a particle accelerator took more time to radioactively decay then they would have taken at a resting state.  weird stuff huh?

though i hope you have found what i said pretty convincing, we must always keep an open mind in this topic, since relatively few FACTS are known about time and much information people hold to be true in this field can actually be labeled as hypothetical and lacking the evidence needed to prove them.  one must not forget, too, that time and time again our science and our logic have been proved wrong and were subsequently altered to better explain the realm in which we live.  so despite what ive said, one cannot really definitively answer your question with what we currently "know"

Answer 15

I think time travel is possible. The inhabitants of earth know so little, so it's hard to tell what has been done and what hasn't. If you do something in the past it changes the future. If the future was changed before it even occured then no one would know or record if or when the change occured.

Answer 16

We are all travelling forwarde in time at the rate of 60 seconds per minute.

Answer 17

A lot of people believe it has been experimented on successfully in something called the Philidelphia Experiment in 1943. Using the Unified Feild Theory the government made a device that would align the molecular structure of a large boat. The boat turned invisible to the naked eye, and traveled in 4 minutes to a port that was an 8 hours away.

The experiment went horribly awry, and people got fused with the ships walls and floors, however if this did happen, then the experiments most definitly continued until they could control the results. There are several cases they believe of planes equiped with this device that disappeared in the bermuda triangle. Of course, the govt was using the reputation of the bermuda triangle to cover up thier experiments.

They would most definitly be able to completely control such things now.

Some say this is all a hoax, but judge for yourself.