Time travel is not possible right?

[Aeson]

Because it's a giant, steaming pile of bull**** wrapped in a thin sheet of sciencey terms. Individual things I said are true-ish, but the whole picture makes not one lick of sense for a dozen different reasons that the average schmuck has no reason to know anything about. But if all you do is daydream about how awesome the universe could be, then you never learn enough to know why that sciencey thing you heard is dead wrong, and then you can never appreciate how awesome the universe actually is based on everything we really do know.

It's like coming to the conclusion that defensive backs are wave phenomena because they can be called for pass interference.

Thus why Star Wars is better than Star Trek.

[My Hubby Loves Civ]

The laws of science do not distinguish between the forward and backward directions of time -- yet they do distinguish the past from the future (time increases as disorder increases). There are some solutions to the equations of General Relativity which would allow for travel back and forth in time....(1) would require that you move faster than the speed of light, but we know that this cannot be done; Tachyons have not been proved. (2) would require space-time to be very warped and a sort of "tunnel" between two space-time points to be present (called a "wormhole"). Such tunnels would not last long enough on their own for anyone to travel through them (unless the traveler discovered some way or built some machine which would keep the tunnel open, which is the point of this discussion. )


There are all sorts of other conditions which would have to be imposed on space-time in order for human beings to travel into the past. All of these conditions tend to conspire against time travel being more than a theoretical possibility. But our understanding of physics causes the possibility of time travel to remain an open question. NOTE: What I have said here is related to big objects like humans...and my comments do not necessarily apply to very small (subatomic) objects.

[Donegeal]

In Feynman diagrams, electrons moving forward through time look identical to positrons moving backward through time. Since the interstellar medium is composed of ionized plasmas (evne if the scientists working for Big G try to hide this fact, as pchang astutely pointed out), which are negatively charged, it's possible that this material is actually positively charged stuff moving backward through time. And since this gravitating material is moving backward through time, it may reverse its gravimetric effects, causing repulsion instead of of attraction. Thus the source of the universe's accelerating expansion--dark energy--could be time-traveling anti-electrons. If we could harness it, we would be able to travel backward through time. And according to special relativity, anything moving faster than light can also create closed time-like curves (time travel), so we would be able to go faster than light as well. It's brilliant! Why hasn't anyone else figured this out yet?!

Great Theory! Now go find out WHY it's a giant steaming pile of bull**** and come back with an adjusted theory to account for the new information.

[My Hubby Loves Civ]

I have been trying unsuccessfully to find an excerpt from Einstein that I recall reading some time back. He was only speculating on the possibility of time travel into the past using FTL means. It said something about if one did that perhaps a paradox would not occur due to the basic fact, the rate and fluctuation of your sub-atomic particles would not match up. You would not be seen nor be able to interact with the distant past, only observe!

I have to admit reading that years ago, was exciting, I am hoping it had been archived somewhere since 1999! I know it was that far back due to where I lived back then and what I had been studying.

Since this is not a science forum per say, I have decided to toss this info out there before I find my proof. Perhaps, someone else has seen it and can direct me to a link.

Edit add: I suppose I will share why I was excited at the time. I was studying paranormal aspects, and wondered if the legitimate cases were not supernatural but scientifically possible. At that time, I thought perhaps, some electromagnetic fields would disrupt the time travelers and out of their control, they would merge momentarily. Thus, the people in the past would mistake them for ghosts, devils, spirits, etc.

[The Mad Monk]

Because it's a giant, steaming pile of bull**** wrapped in a thin sheet of sciencey terms. Individual things I said are true-ish, but the whole picture makes not one lick of sense for a dozen different reasons that the average schmuck has no reason to know anything about. But if all you do is daydream about how awesome the universe could be, then you never learn enough to know why that sciencey thing you heard is dead wrong, and then you can never appreciate how awesome the universe actually is based on everything we really do know.

It's like coming to the conclusion that defensive backs are wave phenomena because they can be called for pass interference.

...or you become Gene Roddenberry.

Yes, I know Aeson already made the point, but I've been waiting since last night to make this point, and I'm making it!

[Lorizael]

Great Theory! Now go find out WHY it's a giant steaming pile of bull**** and come back with an adjusted theory to account for the new information.

Well, my "tHeOrY" started with Feynman diagrams, so I guess I should begin by learning quantum electrodynamics. That means I need to know quantum mechanics and special relativity for background, as well as all the math to support that physics, which includes perturbation theory, gauge theory, and probably some other things as well (not to mention all the calculus and linear algebra I already know which aren't sufficient for doing QED).

[My Hubby Loves Civ]

Note that this is not FTL. But it is the methodology to get there. The time slicing to inject a photon takes time. The method uses 3 photons, two of which are entangled. But, the time it takes an entangled photon to take on the state of the destroyed photon is instantanious. It is only FTL in that instance. Mind boggling stuff.

Scientists have been able to "teleport" photons through fiber optic cables with the ability to provide an encryption key that can never be compromised. Heady stuff. The new record is 60 miles. If this proves sustainable and certainly scalable, it will be a whole new era for networking.

Scientists smash distance record for quantum teleportation Source:

https://www.washingtonpost.com/news/speaking-of-science/wp/2015/09/23/scientists-just-smashed-the-distance-record-for-quantum-teleportation/

Physicists at the National Institute of Standards and Technology (NIST) have broken the quantum teleportation record in a big way. In a paper published this week in Optica, they report successfully transferring information from one photon to another across over 60 miles of fiber-optic cable -- four times the distance of the previous record.

I am so amazed at the discoveries and breakthroughs currently going on in the quantum arena. Proving these theories opens up all of the other incredible revelations of quantum mechanics.

[pchang]

I believe they have achieved up to 88 miles and there are proposals for a space experiment that would be in the thousands of miles. But it is not actually not that big a breakthrough in networking. The encryption key thing allows us to detect that it was intercepted (the state has changed) so we can discard that key and go to the next one. However, to send real information we still need to send a real photon to the receiver so they can compare it to the entangled photon. Thus, no FTL information transfer.