Why Does Back to the Future Require 88 MPH for Time Travel?

[sweetvirgogirl]

sorry, I don't think I'm posting this thread in the right section, but then I'm not sure which section this thread belongs to

I would really like to discuss the movie "Back to the Future (1985)" coz I just saw it ...

btw something I couldn't understand was the significance of 88 miles per hour - that was the speed required in the movie to time travel - but why did they pick 88 miles per hour?

and what's the concept behind flux capacitor?

also, i found the whole pic disappearing thing kinda childish ...

anyway ... your thoughts on the movie?

 

[Danger]

I loved it, but there's absolutely no real science involved in it. This thread should actually be in General Discussion.

 

[FredGarvin]

You're reading waaaayyyyyy too much into the movie.

 

[sweetvirgogirl]

I loved it, but there's absolutely no real science involved in it. This thread should actually be in General Discussion.

yeah no doubt, it's a really entertaining and engaging movie ... but yeah, it's really childish

my teacher asked me to write a paper on it and combine it with time travel and all ...

but after watching the movie, i knew i wouldn't be able to write a paper on it ... coz there's seriously no scienece involved in it

 

[sweetvirgogirl]

You're reading waaaayyyyyy too much into the movie.

heres the deal ...

when i watched, i was going to write a a paper on it ... and discuss the paradoxes associated with timetravel ...

but i don't think i can write a paper on it anymore ... it's way too childish

 

[Danger]

my teacher asked me to write a paper on it and combine it with time travel and all ...

I hope that he meant for you to give an explanation of why time travel is impossible. If he believes in that stuff, he has no right being a teacher.

 

[cronxeh]

I loved it, but there's absolutely no real science involved in it. This thread should actually be in General Discussion.

I second this post exactly. Loved the movie, one of my all time favorites along side with 5th element, but there is [practically] no science in it

 

[franznietzsche]

I second this post exactly. Loved the movie, one of my all time favorites along side with 5th element, but there is [practically] no science in it

Its not just practically devoid of science, it really is devoid of science.

 

[mattmns]

The number 88, if you rotate it 90 degrees you get $$\begin{array}{cc}\infty\\\infty\end{array}$$ Throw on some parenthesis and you have $$\left(\begin{array}{cc}\infty\\\infty\end{array}\right)$$ = undefined, the speed in which you need to reach in order to go back to the future.

 

[Danger]

Brilliant!

 

[franznietzsche]

Brilliant!

Not drink six beers at the same time?
Brilliant!

 

[sweetvirgogirl]

The number 88, if you rotate it 90 degrees you get $$\begin{array}{cc}\infty\\\infty\end{array}$$ Throw on some parenthesis and you have $$\left(\begin{array}{cc}\infty\\\infty\end{array}\right)$$ = undefined, the speed in which you need to reach in order to go back to the future.

what the hell lol

 

[cronxeh]

Its not just practically devoid of science, it really is devoid of science.

I especially loved the part when Doc had that look of horror on his face when he discovered that the tank had no gas in it - while they were in 1885

The words that followed will be etched into the memory of anyone majoring in Chemical Engineering today!

Besides in first part there is a huge speaker with amps and subs, and then there is the refrigerator in third part, and many cool gadgets in 2nd part! (Keep in mind this was 1989!) - 4 years before any practical color video conferencing was even invented!

Frankly, imho, BTTF is the best scifi movie ever made to date. I thought the characters were very well developed and particularly the Doc's character is amazing

 

[loseyourname]

I think what your teacher wants you to look at are the paradoxes that could ensue from time travel. At least that I remember from the movie was the prospect that Marty would become involved with his own mother and keep her from ever getting with his father. Since this would result in his never being born, he could never have gone back to do it in the first place. Doc Brown warns him about these things.

This is strictly philosophical, though. There is nothing scientific about rationally contemplating paradoxes.

 

[cronxeh]

I think what your teacher wants you to look at are the paradoxes that could ensue from time travel. At least that I remember from the movie was the prospect that Marty would become involved with his own mother and keep her from ever getting with his father. Since this would result in his never being born, he could never have gone back to do it in the first place. Doc Brown warns him about these things.

This is strictly philosophical, though. There is nothing scientific about rationally contemplating paradoxes.

There is no scientific theory that states that time travel is impossible

 

[FredGarvin]

"Do you really think I should swear?"

"Yes, damnit George, swear."

My friends and I had a contest in school to see who could go to that movie the most times. We lost count. I know that movie forwards and backwards.

 

[hypatia]

Its in my top ten all time favorit movies

http://whatis88.ytmnd.com/

 

[cronxeh]

You guys will think this is crazy but I was actually seriously considering getting a used DeLorean and adding electroluminiscent strips on side that would be triggered at 88 mph+

and then I wanted to put that same concept on a motorcycle.. and Now I am thinking which one to go with.. car vs motorcycle

 

[Cyrus]

I think you could get all the chicks in this car Fred. You would be the talk of the town anywhere you parked this bad boy. https://www.physicsforums.com/attachments/5857 There was one like this on ebay a while back. It was an exact replica with working flux capacitor and computer to enter in destination time and arrival time! I was looking for that car on ebay and look what I found! http://www.bttf.com/forums/ This movie has a cult following. I think all your anwsers will be found in that site...sad

 

[FredGarvin]

I think you could get all the chicks in this car Fred. You would be the talk of the town anywhere you parked this bad boy. https://www.physicsforums.com/attachments/5857 There was one like this on ebay a while back. It was an exact replica with working flux capacitor and computer to enter in destination time and arrival time! I was looking for that car on ebay and look what I found! http://www.bttf.com/forums/ This movie has a cult following. I think all your anwsers will be found in that site...sad

Whoa. That me be a little more hard core than I ever will be. My friends and I, like most guys, simply like quoting lines. Did you ever find a Delorean on e-bay?

BTW...John Delorean is a fellow alma matter of my college. A little notoriety to start the day.

 

[sweetvirgogirl]

I think what your teacher wants you to look at are the paradoxes that could ensue from time travel. At least that I remember from the movie was the prospect that Marty would become involved with his own mother and keep her from ever getting with his father. Since this would result in his never being born, he could never have gone back to do it in the first place. Doc Brown warns him about these things.

This is strictly philosophical, though. There is nothing scientific about rationally contemplating paradoxes.

interesting ...

now I'm really confused ... what should be my thesis statement?

 

[Plastic Photon]

The first time the Doc is shot, he is already wearing the bulletproof vest.

I love the dad and the son's laugh. Me and my dad use it all the time to annoy mom. 'Ah Ah Ah Ah Ah'.

 

[JesseM]

I hope that he meant for you to give an explanation of why time travel is impossible. If he believes in that stuff, he has no right being a teacher.

Not true, time travel is allowed in certain circumstances by general relativity, so it's a perfectly valid topic for scientific discussion. Most physicists think that quantum gravity will prevent the time travel solutions of GR from actually being possible, but that has by no means been proved yet.

 

[JesseM]

I think what your teacher wants you to look at are the paradoxes that could ensue from time travel. At least that I remember from the movie was the prospect that Marty would become involved with his own mother and keep her from ever getting with his father. Since this would result in his never being born, he could never have gone back to do it in the first place. Doc Brown warns him about these things.

This is strictly philosophical, though. There is nothing scientific about rationally contemplating paradoxes.

Well, the paradoxes show why the idea of "changing the past" within a single history doesn't make sense. There are ways of avoiding such paradoxes though, like the idea that each time you travel to the past you enter a parallel universe where history diverges from the history of the universe you came from, or the idea that history is constrained to be self-consistent, so you will be unable to do anything to change the past. The second solution is the one usually considered by physicists contemplating time travel--see the Novikov self-consistency principle, or the discussion on this thread.

 

[Danger]

Not true, time travel is allowed in certain circumstances by general relativity.

While I'm somewhat familiar with the concept from the perspective of ring singularities, split event horizons, antimatter time-reversal invariance and whatnot, I don't believe that it will ever be technologically possible to transfer anything macroscopic into the past in any condition to affect causality. I'm not sure about that, of course, but it seems extremely unlikely to me.

 

[JesseM]

While I'm somewhat familiar with the concept from the perspective of ring singularities, split event horizons, antimatter time-reversal invariance and whatnot

I was thinking of stable wormholes, held open by exotic matter--this is the most common scenario when discussing time travel in GR. Travelling through a ring singularity might take you some unknown region of spacetime, but there's no reason to think it would be your own past...time-reversal invariance has nothing to do with time travel (after all, Newtonian laws are time-reversible too), and I'm not familiar with the term "split event horizons". (a google search only turns up 19 hits, are you sure you have the term right?)

I don't believe that it will ever be technologically possible to transfer anything macroscopic into the past in any condition to affect causality. I'm not sure about that, of course, but it seems extremely unlikely to me.

But when you were talking about paradoxes and the impossibility of time travel, it seemed like you were using "impossible" in the sense of what's allowed by the laws of nature, not in terms of practical engineering issues. If something leads to a genuine paradox, it must be logically impossible, not just impossible in practice.

 

[Danger]

I was thinking of stable wormholes, held open by exotic matter

As I understand it, an impossible amount of negative energy, rather than exotic matter, would be required to maintain a wormhole.

Travelling through a ring singularity might take you some unknown region of spacetime, but there's no reason to think it would be your own past

When I was informally trying to study up on this stuff almost 30 years ago, there was no mention of ring singularities. The split event horizon was at the time considered to be the consequence of excessive spin or charge on a black hole. It would essentially allow one to cross the event horizon, but miss the singularity to emerge in either a different time or a different region of space. The instantaneous travel to another place was also considered to be backward movement in time equal to the forward movement through space, so that you get there at the same time that you left. Since I never really got back into it, it's quite possible that the ring singularity is the replacement model for the split horizon.

time-reversal invariance has nothing to do with time travel

I'm aware of that; I was actually using that example to support your case about travel being theoretically possible on the quantum level. Since particle interactions going forward are identical to antiparticle ones going backward with parity upheld either way, it might be argued that antimatter is in fact traveling backward in time. On the macroscopic level, of course, causality would cut into screw it up.

But when you were talking about paradoxes and the impossibility of time travel, it seemed like you were using "impossible" in the sense of what's allowed by the laws of nature, not in terms of practical engineering issues. If something leads to a genuine paradox, it must be logically impossible, not just impossible in practice.

That's not exactly what I meant, but pretty close. I don't believe that backward time travel of a macroscopic object can physically occur, regardless of how theoretically possible it might be.
I'm going to hold off on any more comment until Space Tiger or someone else weighs in. This is getting over my head.

 

[Mk]

As I understand it, an impossible amount of negative energy, rather than exotic matter, would be required to maintain a wormhole.

matter:energy::exotic matter:negative energy

 

[cronxeh]

Jesse/Danger

Why would you even want to transform matter over a wormhole? Its too far, not in your lifetime, etc.

If you would agree that consciousness is separate from your body, then it is weightless and capable of traveling through time. Nostradamus did it. And you can do it today with certain chemicals. Its highly debatable but people do it and have OOB experiences. Some end up spending a great chunk of time in some place they don't recognize having intelligent conversations with creatures that don't exist, while their bodies are like zombies and walking around the house on their own. Far fetched? I know it happens, because it happened to me.

 

[StatusX]

The only thing from back to the future that's even remotely accurate is that if you see your future-self in the future, the universe will collapse on itself. It's true, but no one knows why.

 

[Mk]

The only thing from back to the future that's even remotely accurate is that if you see your future-self in the future, the universe will collapse on itself. It's true, but no one knows why.

I would have to disagree. We don't know enough to make any assumptions like that.

 

[franznietzsche]

The only thing from back to the future that's even remotely accurate is that if you see your future-self in the future, the universe will collapse on itself. It's true, but no one knows why.

That's a load of hogwash.

If a particle takes a four dimensional path (as all particles do) the only restrictions would be against faster than light travel (which amounts to traveling backwards in time) and having the path intersect itself (have a particle at the same time and place, twice, would violate the Pauli Exclusion Principle, so obviously I'm talking about fermions). So let's say a fermion went forward in time, and passed near its own path, the particle equivalent of seeing future-self in the future. What would possibly necessitate the collapse of the universe?

Unless you were joking, in which case

 

[JesseM]

The only thing from back to the future that's even remotely accurate is that if you see your future-self in the future, the universe will collapse on itself. It's true, but no one knows why.

You're kidding, right?

 

[StatusX]

Well, that's the last time I try to be funny. Thanks everybody.

 

[franznietzsche]

Well, that's the last time I try to be funny. Thanks everybody.

As I said, in that case

I should add that my humour detector regularly malfunctions. Just ask tribdog and Danger.