# Superman time travel

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## Main Question or Discussion Point

In the movie, when superman flies near light speed, he manages to reverse time? Was the story-line just completely off from a physical perspective or is there some truth to this phenomenon? I understand that time would slow down for superman from a human's perspective. Maybe I just didn't understand what the movie-makers were implying that superman was doing, possibly (or impossibly) travelling faster than c in order to turn back the clock?

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i would think that their reasoning would be correct. however if you put it in einstein's view, he would probably say that it would be rubbish as you need infinite mass to reach light speed. but overall, they are are half correct in showing him do that stunt.

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What was their half-baked reasoning though? Were they implying that travelling near the speed of light will cause backward time travel, or that superman travelled faster than light?

In the movie, when superman flies near light speed, he manages to reverse time? Was the story-line just completely off from a physical perspective or is there some truth to this phenomenon? I understand that time would slow down for superman from a human's perspective. Maybe I just didn't understand what the movie-makers were implying that superman was doing, possibly (or impossibly) travelling faster than c in order to turn back the clock?
I thought he was traveling backwards to the spin of the Earth, turning back the days. I left the room to vomit. Did I over-react?

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I thought he was traveling backwards to the spin of the Earth, turning back the days. I left the room to vomit. Did I over-react?
That idea sounds even worse! They're saying that if you can travel faster than the Earth's rotation (which most jets now-a-days are accomplishing daily) but in the opposite direction, you will travel back in time? :rofl:

DaveC426913
Gold Member
That idea sounds even worse! They're saying that if you can travel faster than the Earth's rotation (which most jets now-a-days are accomplishing daily) but in the opposite direction, you will travel back in time? :rofl:
No. Come on now.

He was clearly flying at relativistic speeds - his path became just a blur (at the speed of light, he would circumnavigate the Earth about 7 times every second. Good thing they're paying attention to detail! )

They're clearly extrapolating that, if time slows down and stops at c, then exceeding c should make it go backwards.

maybe he had some help from his trusty sidekick mathman to renormalise some infinities.

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So he was supposed to be travelling faster than c? Thats quite an amazing velocity to reach! Not to mention the acceleration (he got to max speed in about 3 seconds). Imagine the G-forces this guy was feeling! But then again, a bullet won't penetrate his eye so I'm sure he didn't feel more than a tickle

HallsofIvy
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I thought he was traveling backwards to the spin of the Earth, turning back the days. I left the room to vomit. Did I over-react?
In the old comic-books, that exactly what he did in order to travel back in time!
(Vomiting may have been a bit of an over-reaction.)

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In the old comic-books, that exactly what he did in order to travel back in time!
I doubt these old comics came from before the time of Einstein and relativity. If superman weren't first published as a cartoon and aimed for children, I'd have to question the writers' knowledge of... stuff in general...

I doubt these old comics came from before the time of Einstein and relativity. If superman weren't first published as a cartoon and aimed for children, I'd have to question the writers' knowledge of... stuff in general...
Wait I know! He went around the Earth so fast, he was able to spin the Earth backward via relativistic frame drag, thereby reversing the days. It's all so obvious now.

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Matterwave
Gold Member
I've always thought that he went so fast he made the Earth spin the other way, thus reversing time (obviously that's what'd happen!).

I never saw anything relativistic in this because otherwise he needn't fly in a circle, he could just fly in a straight line, break C, and then fly right back. Also, if it were to do with relativity why did the filmmakers spin the Earth the other way?

Wait I know! He went around the Earth so fast, he was able to spin the Earth backward via relativistic frame drag, thereby reversing the days. It's all so obvious now.
Yeah that's what I thought it was supposed to be, something like that. Ridiculous I know but you can tell this is what they were going for because after he spins the earth one way, he SPINS IT BACK the other way to make time go forward again.

Yeah that's what I thought it was supposed to be, something like that. Ridiculous I know but you can tell this is what they were going for because after he spins the earth one way, he SPINS IT BACK the other way to make time go forward again.

Hmm. I don't know whom's fooling who..

How do you figure he learned that trick, growing up in a barn full of hay, and all?

atyy
Hmm. I don't know whom's fooling who..

How do you figure he learned that trick, growing up in a barn full of hay, and all?
Practised on a chick or piglet.

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Practised on a chick or piglet.
He would have failed everytime due to relativistic reflux of the livestock's intestines.

DaveC426913
Gold Member
What astonished me was not the idea that he could fly faster than the speed of light thus travelling back in time, it was that he could fly faster than the speed of light to reverse time. (Subtle difference.)

He flew really fast.
The Earth stopped and reversed its rotation.
He stopped flying fast.
The Earth continued to rotate in the opposite direction.
He flew real fast the other way.
The Earth stopped and reversed its rotation back to normal.

See, there was a period of a few seconds there where he was flying normally and Earth was continuing to rotate backwards. The implication is that, if he has decided to go land, he would see everybody walking backwards, etc.

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Hehe nice observation DaveC.

I'm also wondering if it truly is possible to reverse the spin of the such a large mass as the Earth that quickly with a mass of a normal human travelling near the speed of light. I'm unsure of what the physical phenomenon of this is called though. I'm guessing it could happen due to the atmosphere moving with superman, and thus slowly re-rotating the Earth in the opposite direction with superman. But again, superman clearly flew at least half the radius of the Earth into space before his flight so the atmosphere there would be so very thin?

On a more serious note, at school we were taught that although the speed of superman was, of course, variable, it was the same all reference frames.

Matheinste.

DaveC426913
Gold Member
Hehe nice observation DaveC.

I'm also wondering if it truly is possible to reverse the spin of the such a large mass as the Earth that quickly with a mass of a normal human travelling near the speed of light. I'm unsure of what the physical phenomenon of this is called though. I'm guessing it could happen due to the atmosphere moving with superman, and thus slowly re-rotating the Earth in the opposite direction with superman. But again, superman clearly flew at least half the radius of the Earth into space before his flight so the atmosphere there would be so very thin?
What? No! He flew faster than the speed of light. He traveled backward in time. He did not do anything to the Earth at all. We were seeing the Earth from his point of view, while he was travelling backward in time.

DaveC426913
Gold Member
BTW, this really ought to be moved to General Discussion. It is about movie junk-physics, and has nothing to do with real physics at all.

isn't this whole argument a bit irrelevant anyway. after all, won't he go beyond the escape velocity of earth after reaching light speed and shoot out into space away from earth, rather than keep going around it.

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What? No! He flew faster than the speed of light. He traveled backward in time. He did not do anything to the Earth at all. We were seeing the Earth from his point of view, while he was travelling backward in time.
No I don't think that's what they were going for. If that was the case time would have stopped traveling backward as soon as he stopped even though the whole idea is flawed. He flew in one direction to spin the earth the other way and somehow earths rotation is linked with earths time. If ur way was true, he would be making time go backwards regardless of his direction. He's traveling faster than C both times.

Wait a minute DaveC, im not exactly an expert on Relativity "and all that" but i thought that if you accelerated to the speed of light then time would'nt stop but it would speed up. I respect you position as a PF contributer and a Scientific adviser but i have thought through your hypothsis in situtions featuring the basic laws of Relativity and it doesn't seem to add up.

For example, the sitution that if you left the earth for 20 minutes going through space at 99% the speed of light your biological clock would slow down in comparission to someone else biological clock on earth. Meaning that when you returned to earth you would have aged slightly less than whoevers biological clock you are compared to.

I have gone other and other again through this situtation using your hypothesis and it how'd you say "DOE'S NOT COMPUTE". Please explain how your theory complies with the above situation.

DaveC426913
Gold Member
isn't this whole argument a bit irrelevant anyway. after all, won't he go beyond the escape velocity of earth after reaching light speed and shoot out into space away from earth, rather than keep going around it.
No, he's in controlled flight, not a ballistic trajectory.