Thread: Is time travel possible? At first i ....

Originally Posted by Taxpayer

4 dimensional: x, y, z, t

you are right,

Originally Posted by The DARK LORD

DIDNT think so, but now I have proof it is possible, theoretically. Anyone care to pipe in?
Alternate universes is a cool idea, but have no rational substance to sustain such a belief.

Time does not fit on a horizontal line as we so commonly think of it. Time is three dimensional.

think about the speed of light, and distances,
distance = time.....

A lot of over-educated morons claim that if you travel faster than the speed of light you break the time barrier. I call bull(*)(*)(*)(*). I say time isn't limited by the speed of light. If you travel faster than the speed of light then you travel faster than perceived time, ie you can turn around and see yourself. But that doesn't mean a fraction of time hasn't passed because it has.

Yes, time travel is theoretically possible. But it would be very difficult because the energy associated with an object's rest mass has to be overcome.

A typical setup for time travel involves two fast moving supermassive black holes flying past eachother. If you pilot your spaceship towards the gap where they have already just converged in the immediate past, the gravity from the past could fling your spaceship into the past. The blackholes must be extremely massive, and the gap distance sufficient to create a uniform gravitational field, otherwise your spaceship would simply be torn to pieces.

In reality, simply two black holes would probably not be enough. One would have to align several stages of black hole pairs in a sequence for this to practically work.

Tremendous energies need to be involved for time travel, and these energies must be carefully controlled if you do not want to be merely blown apart into subatomic particles. Suffice to say humans do not currently have the capacity for sending any significant quantity of matter back in time. It may be possible to send signals a fraction of a second back in time using current technology. While scientists do not know with certaintly, likely there would not be any "paradox" phenomena observable. Coherence and quantum entanglement prevent this. On much more macroscopic scales, this type of paradox-preventing phenomena would have much more bizarre manifestations. For example, someone who tries to go back in time to kill themselves before they were born would find that it was impossible because strange (extremely unlikely) coincidences would thwart their efforts.

Also, going back further into time might be exponentially more difficult, because of interraction between "the butterfly effect" and statistical resistance to paradox-formation. Going back in time 1000 years and touching even a single blade of grass would hypothetically substancially alter the outcome of the future, so the time-loop of existence would need to compensate to prevent the future from being altered (which would create a paradox forbidden by the laws of nature). Statistically, the more the time-loop would need to "compensate", the more difficult it may be to go back in time. Notice that by "compensate", this is not an actual event in time, it is merely something which exists as part of time, a simple relationship between events. Trying to understand sequences of events in terms of "cause and effect" becomes meaningless in time travel.

Indeed, it might even be possible that the failure of any scientists to attempt to send a signal back in time could actually be a macroscopic manifestation of this bizzare law of nature, to prevent any paradox from forming, although this is just baseless thought-provoking conjecture on my part.

The energy needed to travel faster than the speed of light is not there... because the faster something moves the more force it takes to push it.

When you get near the speed of the light the mass of any object (that has mass) is so large you cannot muster enough force to push it faster. It "weighs" too much.

Place a baseball on your bare foot....then drop a baseball on your bare foot from shoulder height if you disagree.

Originally Posted by politicalcenter

When you get near the speed of the light the mass of any object (that has mass) is so large you cannot muster enough force to push it faster. It "weighs" too much.

Some physicists think this could be because of coupling with the background energy (the Higgs boson or the quantum vacuum, "empty space" actually contains energy). An object only "increases" in mass because it begins to have more interaction with surrounding energy at higher velocities. The very fabric of space-time may actually be plain energy. Take away this energy, and an object could theoretically move with infinite speed. Reduce this energy in a particular location and space-time would become "warped".

This could be why neutrinos have been able to exceed the speed of light, since they have such little interaction.

Originally Posted by politicalcenter

The energy needed to travel faster than the speed of light is not there.

This may not necessarily be true. There could be "non-linear" effects at extremely high energy-velocities, essentially the effect of continuosuly "gaining mass" could start to level off. This can be seen in lasers traveling through a dielectric medium (like a crystal). At suffiently high energy densities, the dielectric constant changes, and the light can travel faster through the medium than it otherwise normally could.

Since the vacuum energy has an extremely high energy density, the energy of a particle would have to be extremely high for it to exceed light speed, which has never been observed.

The other strategy would be to "rarify" the vacuum. Essentially two reflective parrellel plates (Casmir effect) on a huge scale (many lightyears wide), could allow a particle to travel slightly faster than the speed of light. But from another persective, since the space between the plates would be warped, the speed of light would still be conserved within the framework of relativity.

I'd like to mention particle accelerators.

We've observed time dilation in those.

But using atomic clocks we've also observed time dilation on planes.

As I said, we're always time travelling.

Originally Posted by Panzerkampfwagen

I'd like to mention particle accelerators.

We've observed time dilation in those.

But using atomic clocks we've also observed time dilation on planes.

As I said, we're always time travelling.

It appears to be much easier to slow time than it is to speed it up. And going back in time would be extremely difficult. I would even wonder whether in the entire universe's existence any bit of matter has ever been sent back in time through natural cosmic processes. I would think that in a collision between two black holes, some small fraction of the matter might get ejected back in time, although it might not escape.

I still follow Al.

It may be possible to warp space but that would not be traveling FTL...the object we were travelling to would be closer.

If you could warp the space between here and Mars to make the journey in an hour. The hour journey would be in real time.

You would get there an hour after you left Earth. Mars time and Earth time.

My guess is that going back in time would be even more difficult than people imagine. The normal fabric of space would likely try to resist anything going back in time, just like it resists anything trying to exceed the speed of light. To send something back in time, likely space would have to be extremely warped also. If you want to think of it this way: a temporary man-made "worm hole" into the past.

We know space-time is affected by gravitational fields.

Originally Posted by politicalcenter

I don't think past and future even exist.

Many scientists view time is the "fourth dimension".

I believe the past and future exist in the same way that the present exists. Think of it this way: you only believe the present exists because it is the present you that is thinking. The past you, 1 hour ago, thinks the exact same thing.

Time only appears to flow from the human perspective. It has already been demonstated through quantum entaglement, and phenomena such as the double slit experiment, that the "cause and effect" relationship is an illusion. There is a connection, a correlation between the past and future, certainly, but there are instances we see where the future appears to affect the past. This phenomena is typically not obvious in ordinary human existence, though it is necessary to explain why we can even see our reflection in a mirror. If it was not for the fact that photons are forbiden to annhilate eachother in the future, there would be no coherence, and without coherence, all the photons reflecting from a mirrow would bounce off in random directions, because each individual photon is actually transiently absorbed by individual spherical atoms.

It seems to me that there really isn't much difference between the "energetic fabric of space-time" that we all plough through and the classical notion of an ethereal plane overlaid with the physical plane. But the notion of 2 black holes actually sending a sizeable something back in time, compared with the theory of "one timeline", where all time travel changes have already been factored in to what is, was, and will be, reminds me of an explanation for the Big Bang that I heard once: That "stuff" came back from a possible future, destabilizing the singularity. With a universe that seems to have preferences to prevent paradox, preferences to do everything with the least effort, perhaps it prefers to exist?