Time travel is possible

[The-Sir]

Must have been a short program?

 

Here is what we know for sure:

 

 

 

Thats like... dark, man.

[dirty_sanchez]

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[Ginny]

I reckon Stephen Hawkings is a bad bellend and needs to sort his head out

[Stu Monty]

Monty, any idea what it was called mate? Might try and find it on Youtube if you have a name.

 

May I recommend BBC Horizon's documentaries on String Theory and Parallel Universes. They're on Youtube if you fancy a gander.

 

It was a Horizon one and I think it was called "What if everything we know about the universe is wrong". It was rather brilliant. As NN is sugesting the terms are really only easy labels to put on the areas of ignorance we still have about these things. The fact that you see scientists aware of that and still searching for answers, and also searching to prove wrong what we currently think right, is a great thing.

 

Edit - Here you go mate, found it for you:

 

ge6RjTgyLr0&feature=related

[Guest Numero Veinticinco]

Monty, any idea what it was called mate? Might try and find it on Youtube if you have a name.

 

May I recommend BBC Horizon's documentaries on String Theory and Parallel Universes. They're on Youtube if you fancy a gander.

 

The BBC, for all their faults, are just brilliant at this sort of program. They do it impeccably well.

 

It was a Horizon one and I think it was called "What if everything we know about the universe is wrong". It was rather brilliant. As NN is sugesting the terms are really only easy labels to put on the areas of ignorance we still have about these things. The fact that you see scientists aware of that and still searching for answers, and also searching to prove wrong what we currently think right, is a great thing.

 

Edit - Here you go mate, found it for you:

 

ge6RjTgyLr0&feature=related

 

 

Yes, I watched that a while back and linked it in a recent thread about religion or something else. Bloody good that was. The fact that we have no idea about 95% of... erm... stuff... other than we know we don't know about it, is so exciting.

 

I would love a link to those other programs though, Chris.

[Guest Numero Veinticinco]

Is it this?

 

80jxKQP2V0Y

[mars]

I find the idea that "if you travel fast enough you will slow time down" a little retarded.

 

Surely you will just be travelling really, really fast?

 

Time is a constant I dont see how distance travelled can affect it.

 

The idea certainly goes against our everyday experience but there are experiments that support Special Relativity - see David H. Frisch and James A. Smith, Measurement of the Relativistic Time Dilation Using Muons, American Journal of Physics, 31, 342, 1963.

 

What's weird is that you wouldn't feel any different, but people observing you would record a slower heartbeat, etc.

[AngryOfTuebrook]

I find the idea that "if you travel fast enough you will slow time down" a little retarded.

 

Surely you will just be travelling really, really fast?

 

Time is a constant I dont see how distance travelled can affect it.

Smartarse physicists would neg you for that one.

 

Mind you, they also say shit like "The gravity in a black hole is so strong that time can't escape." And they keep a straight face when they say it.

[AngryOfTuebrook]

I want to go into the future to see how Si's invention works out.

[harryo63]

According to Stephen Hawking:

 

Stephen Hawking backs possibility of time travel millions of years into the future | Mail Online

why doesnt he go back in time then to before he ended up like he is now

[razor]

Surely the cause is a super fast space ship. Or travelling faster than the speed of light. Or a combination of these factors.

 

But that's breaking the cause/effect continuum, isn't it? That's the point. Time travellers are reaching an "effect" point without the "cause".

 

So what's the difference reaching a "cause" by going BACK in time?

 

Science, schmience.

 

As an alternative to religion, it's got as many questions to answer, hasn't it?

[Guest simon]

I read something not long back about Teleportations has been invented but Scientists have only managed to Teleport an Atom haha what fucking use is that.

[Guest Numero Veinticinco]

I read something not long back about Teleportations has been invented but Scientists have only managed to Teleport an Atom haha what fucking use is that.

 

You've got to start somewhere, Simon. It's not, like, an exact science.

[Guest The Big Green Bastard]

Done it the other day, unfortunately i can't go into detail otherwise our timeline might collapse.

[Guest Numero Veinticinco]

Done it the other day, unfortunately i can't go into detail otherwise our timeline might collapse.

 

Who wins the erection ¿

[JohnnyH]

Tee hee. I'm laughing at the people on this thread telling Hawkings that he's talking shite. Lucky we have so many genius theoretical physicists on here to contradict him.

[Guest The Chimp]

Tee hee. I'm laughing at the people on this thread telling Hawkings that he's talking shite. Lucky we have so many genius theoretical physicists on here to contradict him.

 

Stephen Hawkwind then:

 

 

Stephen Hawkwind now:

 

 

I admire the fact that he can still get groupies, but c'mon he's an ex-hippie and should leave this type of stuff to theoretical physicists.

[AngryOfTuebrook]

But that's breaking the cause/effect continuum, isn't it? That's the point. Time travellers are reaching an "effect" point without the "cause".

 

So what's the difference reaching a "cause" by going BACK in time?

 

Science, schmience.

 

As an alternative to religion, it's got as many questions to answer, hasn't it?

That's sort of the point. Religion claims to have all the answers and demands you to believe them. Science raises questions, proposes hypotheses, tests those hypotheses and then challenges everyone else to come up with better hypotheses. All this time-travel stuff is just a hypothesis that can't be properly tested yet.

[armchairfan]

"There are many physicists who will tell you it is proven impossible," said Richard Muller, a physics professor at the University of California, Berkeley. "But that is not the case."

 

"Einstein himself pointed out that time travel is possible in general relativity," added Gregory Benford, a science fiction writer and physicist at the University of California, Irvine.

 

Einstein's theory of relativity suggests that, if a person could safely travel at or near light speed—a big if—he or she would experience the alteration of time. In a staple scenario of post-Wells fiction, the traveler would arrive in the future not a day older than when he or she left.

 

Getting home—going backward in time—is a thornier problem but may be accomplished by harnessing theoretical particles called tachyons. The as-yet-unobserved particles travel backward in time, some physicists speculate.

 

And below

 

Why FTL implies time travel (tachyon pistols)

 

The entire "FTL implies time travel" meme has to do with what's sometimes called "failure of simultaneity at a distance". In addition to the effects that pop treatments of relativity mention (that is, time dilation and length contraction), relativity proposes that the definition of "right now" is also different, depending on which observer's coordinate system you use. This is an effect much like the revolution of deciding that the direction "up" wasn't the same everywhere, but varied from place to place on earth. With relativity, the revolutionary notion is that the direction "futureward" (or "now-ward") isn't the same everywhere, and varies with velocity.

 

We can describe this effect by idealizing FTL to be "instantaneous", and describing how the more familar time dilation implies this effect. But remember, the same points apply to any FTL speed, you just have more messy arithmetic to grind through.

 

Consider a duel with tachyon pistols. Two duelists, A and B, are to stand back to back, then start out at 0.866 lightspeed for 8 seconds, turn, and fire. Tachyon pistol rounds move so fast, they are instantaneous for all practical purposes.

 

So, the duelists both set out --- at 0.866 lightspeed each relative to the other, so that the time dilation factor is 2 between them. Duelist A counts off 8 lightseconds, turns, and fires. Now, according to A (since in relativity all inertial frames are equally valid) B's the one who's moving, so B's clock is ticking at half-speed. Thus, the tachyon round hits B in the back as B's clock ticks 4 seconds.

 

Now B (according to relativity) has every right to consider A as moving, and thus, A is the one with the slowed clock. So, as B is hit in the back at tick 4, in outrage at A's firing before 8 seconds are up, B manages to turn and fire before being overcome by his fatal wound. And since in B's frame of reference it's A's clock that ticks slow, B's round hits A, striking A dead instantly, at A's second tick; a full six seconds before A fired the original round. A classic grandfather paradox.

 

Note, this is NOT a matter of when light gets to an observer, it is NOT an optical illusion. It is due to the fact that, in SR, the question of what occurs at the "same time as" something else is observer dependent.

 

As A fired that first show at tick 8, the bullet effectively teleported from A's gun to B's back instantly --- instantly according to A. But for B, who was moving at 0.866 lightspeed WRT A, B was hit in the back by the bullet 4 seconds BEFORE the bullet was fired. And again note, this is NOT due to the optical illusion of lightspeed delay in viewing A's turn-and-shoot; the light form that event wouldn't reach B until MUCH later, not tick 4.

 

The one I do like regarding travelling at close to the speed of light regards a train entering a tunnel, the tunnel is say 500ft long and the train is 100ft in length. If you where to shut the door at one point then the whole of the train in theory would be inside the tunnel.

 

There is also one regarding a tachyon gun being used in a murder where the defendant claims to of both shot and NOT shot the person which theoretically is correct.

[Spy Bee]

The one I do like regarding travelling at close to the speed of light regards a train entering a tunnel, the tunnel is say 500ft long and the train is 100ft in length. If you where to shut the door at one point then the whole of the train in theory would be inside the tunnel.

Yes, I find that quite easy to imagine.

 

--- = tunnel

* = train

 

-----

*

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[Guest Numero Veinticinco]

Choo Choo.

[armchairfan]

Whoops, I mean the train was a 1000ft in length.:wallbutt:

[Mel Wood]

Never mind trains, we'd have had this lark sussed by now if they hadn't stopped making DeLoreans.

[Red Phoenix]

I don't think we know shit to be honest, compared to what we eventually will do. And Bowie is surely from the future, so there goes Hawkwind's impossibility.

[Sandman]

I'd much rather they got a move on with that whole laser propelled space ship thing, so that we can see what it's like on Mars before we die.

 

Time travel is no good to any of us posting on here!