MovieChat Forums > Into the Universe with Stephen Hawking (2010) Discussion > time travel

time travel

posted 13 years ago by blackmetallic
11 replies | jump to latest

I just watched the time travel episode and I need something explained to me. In the part where he does the experiment to see if time travel to the past is possible, if the future hasn't happened yet and there is no one to have discovered the note at the time he filmed the episode, how can he prove time travel either way? Wouldn't he have to wait the length of time it takes to discover time travel and then see if anyone came to the party? In a thousand years the experiment could be proven or not but not a day after he writes the invitation. I don't get it.

[–] armored-p 13 years ago

You are right of course, but he was speaking hypothetically. As an example so to speak. Presuming that his invitation will remain preserved and attainable/noticeable to people in the future, for as long as it takes for the people to invent time travel. In that case (and in the case the people in the future want/are allowed to travel back in time) you would presume them to come to the party. But as it stands it is just a thought experiment, a quirky notion of messing around with ideas. It is not like he really did sent out invitations. He was just trying to explain how these things work to the untrained minds out there...

Actually I always found the example better if lets say you are a group scientists working on making time travel possible, they could test right at the start of the research whether they will succeed in their goal before their lives end, by just promising themselves to travel back to the start and telling themselves they succeeded.

[–] blackmetallic 13 years ago

Thanks for responding. I realize it was meant to be an example but then later in the episode he says that the real reason no one came to his party was because there would be feedback from wormholes that would destroy themselves making time travel to the past impossible (or something like that). It made it sound as if he expected his experiment to work. That's what threw me off.

[–] wrxsti2007 12 years ago

I think he always believed it impossible and just showed the experiment as proof that nothing would happen. Then with the whole feedback/wormhole theory he explained why he believes it is not possible. Of course these are just theories and nothing is certain as of yet.

[–] Strazdamonas 9 years ago

No, he said that the reason noone came to the party is because it would create a paradox and the universe would not allow paradoxes because that would turn entire universe into chaos.

The feedback thing was explaining why the wormhole would not be openable to begin with because it would not be able to stay open long enough for us to do anything with it as it would obliterate itself the moment it would open.

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Applied Science? All science is applied. Eventually.

[–] MaxMix7 12 years ago

Traveling back in time is impossible, because nobody showed up to Stephen's party lol

[–] distant-skies 12 years ago

Maybe they were late. Oh well, we'll never know.

Why can't you be a non-conformist like everyone else?

[–] Thrillseeker303 11 years ago

Time travel is a myth. It's impossible.
Stephen Hawking may have some interesting theories but when it comes to time travel he's living in his own fantasy world.
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[–] masuka-fan 11 years ago

Did you watch the show? He did, in fact, say that it was impossible, and explained why he thought so.

"Passion is just insanity in a cashmere sweater!"

[–] Thrillseeker303 11 years ago

Yes. He said if it were possible then people from the future would have already visited us in the present time.
Very good proof that it's impossible.
But still they make a whole show about theories how it could be possible. Wormholes, light-travel, black holes,.. It's quite contradictory to say something impossible could be possible.
It's either possible or it isn't.
In this case it isn't. All the rest is fantasy.

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[–] Strazdamonas 9 years ago

He has explained how under current laws of physics time travel into the future is theoretically possible. for you to claim it is not simply makes you wrong.

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Applied Science? All science is applied. Eventually.

[–] padzok 9 years ago

Wouldn't he have to wait the length of time it takes to discover time travel and then see if anyone came to the party?

Well, no.

That wouldnt be an experiment to see if time travel was possible, that would just be an experiment to see if he was popular/famous enough for people to want to come to his party.

If time travel has already been invented, there is no reason to do the party experiment to see if time travel is possible.

His claim (which does not necessarily stand up to close scrutiny) was that as soon as 10 (?) June 2009 has gone past, we know time travel is not possible because no-one travelled back to 10 June 2009 from the future.

He is correct as a matter of logic (although I think that his experiment proves nothing in practice). In theory it would not matter if time travel was invented in 2029, 2099 or 3009. Whenever it was invented, the time traveller could (he suggests) travel back to 10 June 2009. So, he reckons, the result of the experiment is known on that date.