Time Travel is Science Fiction

[krash661]

You're the one that thinks morning in China is a California afternoon's future. I've asked you to explain your nonsense , and your only reply is that it's all too sophisticated for me to understand. Why not just admit that you're stupid? or that your English fluency hasn't progressed beyond the ability to compose bad haiku?

now you resort to grammar policing.

 

[Landau Roof]

Krash, you do have an obligation to make sense.

"the event occurs at the same time.
in california, it may be three pm.
in china it will be 3-4 am next day."

is babble. Why won't you tell us what you meant? I don't think the E-R bridge is any explanation. Time zones have different time designations but they are not the future or past as you seem to think. If you don't think this, simply say so.

 

[krash661]

two things,
1)http://www.sciforums.com/threads/time-travel-is-science-fiction.140847/page-33#post-3246683
2)http://www.sciforums.com/threads/time-travel-is-science-fiction.140847/page-33#post-3246679
also, think about other physics that are involved with time and time travel.
this will help with overall understanding.

 

[brucep]

So I'm having my morning coffee and checking my forum alerts and opening a few other tabs off-forum when I see this:
Time Travel Is Real. Here Are the People and Spacecraft Who Have Done It
All right. I'm very opened-minded, or like to suppose I am, so I click the link... and it's good that I did because, guess what, the headline is a totally misleading bit of the old bait and switch routine. If you care to click the link, you will see that it's a Wired.com light pop-sci piece about time dilation. For those who have been following this thread and refuse to accept that time dilation is not time travel, this article ought to show you how travel and dilation differ.

Also note that it says of time dilation,"it means that when [visitors who have made long visits to the ISS] return they’re a bit younger than they would have been—as if they’ve traveled into the future. (The effect is very small—it would take more than 100 years on the ISS to warp ahead by just one second.)"

You might find this interesting. I'll list three examples in response to comments you made in your post. The first is the relativistic rocket. The example is theoretically possible if we could solve some huge technological problems. At g_earth constant acceleration for 1/2 the journey and constant g_earth deceleration over the 2nd 1/2 of the journey we could reach the Andromeda Galaxy in 28 years measured on the ships clock. Measured on the Earth clock 2 million years would pass. So if the rocket crew turned around and came back to Earth 4 million years would have passed since the rocket started the journey.

http://math.ucr.edu/home/baez/physics/Relativity/SR/rocket.html

The 2nd example would be for the GPS. Derived by modeling the near earth spacetime with Schwarzschild coordinates. The formula is [12] in QUERY 8. For the GPS the satellite clock ticks faster [infinitesimal] than the clock on the surface of the earth [the v for the clock on the earth surface isn't an orbit. It represents the angular velocity at the earths surface due to the earth rotation on its axis]. This formula includes both time dilation components, relative velocity and gravitational. You can use this formula for calculating predictions for all the orbiting hardware in our near earth spacetime. As you pointed out the ISS clock ticks slower than the earth clock [the relative velocity component rules over the gravitational component for this event].

Choose the GPS project
http://www.eftaylor.com/download.html#general_relativity

The 3rd example is self explanatory, I hope. It's what I like to call the time travel equation. Skip the derivation and go to the example where the rocket warps from ISS orbit to the black hole. Sets up a knife edge orbit just outside the photon sphere, terminates the orbit and warps back to the ISS.

Problem 7, page 4-32, Exploring Black Holes.\

The derivation

Put the derivative of the effective potential term (from the equation of motion) into quadratic form (to find critical values)

r*^2 - L*^2r + 3L*^2 = 0

Where

r* = r/M, and L* = L/mM

Then divide through by L*^2 and manipulate to get

r*^2/L*^2 = r* - 3 [saving this for a later
substitution]

Setting dr = 0 in the Schwarzchild metric and
substituting dphi = (L*/r*^2)dTau the metric becomes

dTau^2 = (1 - 2/r*)dt^2 - (L*^2/r*^2)dTau^2

To find the ratio dTau^2/dt^2 divide through by the
bookkeeper time dt^2 and simplify to

(dTau/dt)^2 = (1 - 2/r*) / (1 + L*^2/r*^2)

Now substitute 1/(r*-3) for L*^2/r*^2 and simplify to

dTau/dt = (1 - 3M/r)^1/2

This following example uses the time travel equation in a way which might be interesting to you. Note that the time intervals dTau and dt are different but that they both measure time intervals as recorded by a clock in a specific coordinate system. dt for Earth and dTau for the spaceship orbiting the black hole.

Abe signs on with the crew of 'Warp Drive 1' while Bill remains on Earth. Warp Drive 1's maiden voyage is to visit a solar mass (M = 1477 meters) black hole, free fall to a knife edge orbit just outside the photon sphere at r = 3.000001M, remain in orbit for 172,800 seconds (Two Earth days) wristwatch time (dTau), and then return to Earth arriving ~ 9.5 years in Earths future. During the warp phase of the journey the ship remains in an inertial rest frame so the difference in wristwatch rate for Abe and Bill is minimal during this phase of the journey.

Lets make a prediction, before the ship leaves, to test General Relativity. What will be the difference in elapsed wristwatch time, dTau, for Abe with respect to the elapsed coordinate time, dt, for Bill when they meet upon Abe's return? Keeping in mind that dTau is measured with Abe's wristwatch (shipframe) and the coordinate time for
Bill is measured with Bill's wristwatch (Earthframe).

From the Schwarzchild geometry a time travel equation

dTau/dt = (1-3M/r)^1/2

Substituting 172,800 seconds for dTau, 3.000001M for r, and 1477 meter for M, then solving for dt

dt = 172,800s / 5.7735E-4 = 299298529.2s

Since there are 3.156E7 seconds / Earth year

299298529.2 seconds / 3.156E7 seconds / Earth year
= ~ 9.48 Earth year

When Abe returns the twins can determine whether the prediction was correct by just comparing clocks.

So you might play with this in the weak field. Set r for an orbit around the Sun. This equation includes the gravitational and SR component of time dilation.

dTau/dt = (1-3M/r)^1/2

 

[paddoboy]

Can you say, "false analogy"?

What is it that you regret so much you need time travel to be real? Never mind, bad haircuts heal with...time.

Oh, stop it with the pathetic jokes and misinformation!
No one needs anything. All that most here are saying is that time travel is not forbidden.And obviously, quite obviously, any sufficiently advanced civilisation could achieve it.
And you whinge about false analogies?
It is really a pity that science forums such as this is open to every landau, Farsight and theorist constant.

If we could only decide to be good, and somehow stick to it, we wouldn't need to go to Mars or the restaurant at the end of the universe or 'boldly go where no man has gone before'. We don't need to turn back the clock. What we need is the strength to be righteous and never falter. However, we're mere men and women, and we will weaken and screw up sooner or later. Dreaming of time travel changes nothing.

OMFG! You just brought a tear to my eye and a lump to my throat! [tic mode on of course]

In reality if it wasn't for the dreamers of this world and those always striving to go one step further, we all would still be swinging in the trees.
How pathetically inane to even suggest we dont need to do any of those things.
But your probably not seeing this as you did say you had me on ignore.....Another example of a copout.

 

[paddoboy]

but we cannot travel back through time. That's my opinion, and the opinion of many others. If you disagree, it's been noted, but please do explain beyond 'some really smart people 120 years ago thought planes would never fly' how and why time travel can be.

More dishonest Farsight like misinterpretations.
no one is saying that.
The accepted mainstream view is based on fact:
That fact is simply that time travel is not forbidden by the laws of physics
Your dishonesty in ignoring that fact is mind blowing.

 

[paddoboy]

This is the classic "argument from incredulity." As Beer/Straw alludes to, it is often used by creationists - "I can't understand how evolution works, so it must be impossible."

Bingo!

 

[paddoboy]

Thosewho do say it is possible have not gone beyond saying that they think so without offering any how or why.

Liar, liar, pants on fire!
check out brucep,s last post at post 664

 

[Trippy]

Don't be such a hard case, why don't you?

That's certainly one way of looking at the statement, I suppose.

While I admit to not being well versed in physics and um, the ins and outs of time travel (or Santa or unicorns), I thought we were here to discuss possibilities, and share views.

Farsight created this thread so he could preach the good news and report anybody who disagreed with him. Others sought to discuss the matter with Farsight, much to their own folly. The OP isn't typically interested in having discussions with people unless they agree with him, it's a pattern of behaviour that's been playing itself out since at least 2007 across multiple internet fora - I participate in two other fora (as a chatter) from which he has been permanently banned precisely because of this pattern of behaviour and the disruption his evangelical preaching causes.

On the other hand, in any given discussion on a public medium neccessarily stretches across multiple levels of understanding and expertise, sometimes establishing the level of understanding of your interloqutor is neccessary for reasonable discourse to occur - after all, offering you explanations, examples, and opinions that are manifestly over your head is as much a waste of your time as it is mine, correct?

Finally, do you not see a moral or philosophical objection to evangelical opposition to something you do not understand? I use the word evangelical here because it seems an approriate word to use when someone uses phrases like 'starry eyed' and starts talking about science as a faith in an effort to try and disparage explanations they do not like and can-not otherwise attack.

What you are doing is deliberately asking a question no one can answer and then calling me ignorant because I cannot answer.

Nonsense. There is one correct answer to the question. Then there are a bunch of conjectures as to why that correct answer may not be realistic or feasable, and some more conjectures as to why thos conjectures may themselves be flawed meaning that the original answer may be feasable after all.

However, I stand by my reply. Black holes, white holes, worm holes, time travel are all mere speculation.

They're not speculation. The existence of faeries is speculation, the existence of unicorns is speculation.

Blackholes, whiteholes, and wormholes are theoretical predictions that are made as solutions to the einstein field equations and various space-time metrics, each of which has theoretical reasons, many based on these same solutions, as to why they may not be stable phenomena in the universe we observe around us.

I know this is true, and you do too. You say, "physics as we understand it"

Yes, I say physics as we understand it, I even talk about physics as I understand it.

Look, the simple fact of the matter is that everybody who has ever actually studied relativity and quantum mechanics knows that both theories are incomplete, we know this because they have mutually exclusive views of how space-time works. This is why we research things like string theory and loop quantum gravity - because they provide solutions for this problem that do not exist in modern physics, and provide us with a quantum theory of gravity. This is why we use astronomical observations to test relativity in increasingly extreme environments - in the hope that we might detect some deviation between relativity and reality that might point the way to what will replace it.

Do white holes exist? We don't know. At this point they remain a prediction of relativity that, as far as we know anyway, has yet to be oserved, however, their observation has implications because there are some solutions that predict we shouldn't see them in this universe, and that their observation in this universe has implications regarding the stability of black holes.

Do wormholes exist? We don't know. At this point, if they do exist we don't expect them to look like the schwarzchild solution because we don't expect to see whiteholes in this universe. Then again, maybe the multiverse theory is correct and they behave exactly as the schwarzchild metric predicts but they connect to some other, very different place.

Do blackholes exist? Almost certainly, there's far too much observational evidence that suggests their existence, and much of that evidence points to the kerr-newman rotating blackhole as being the best model this side of the event horizon. What lies inside the event horizon? We don't know. Relativity, combined with particle physics predicts a singularity of zero size. I've always been of the understanding that this is just, in essence relativities way of saying "Nope, fuck that shit, you're on your own here" and that relativity is expected to break down somewhere inside the event horizon and be replaced by something else that we don't have yet. This is where things like loop-quantum gravity or string theory come in.

At least, as I understand it.

- Hah! We are mere monkeys' uncles trying to understand what might not be understandable even if we did have complete information, and we do not have complete information.

Are you a creationist? This kind of rhetoric sure makes you sound like one. If you want to discuss the moral and philosophical implications and meanings of 'truth' then we have a subforum or two just for that, thihs one, however, is physics and math.

I notice you haven't given your views at all.

Or maybe I have and you've just been too busy delving into the mucky-muck to notice.

 

[paddoboy]

Blackholes, whiteholes, and wormholes are theoretical predictions that are made as solutions to the einstein field equations and various space-time metrics, each of which has theoretical reasons, many based on these same solutions, as to why they may not be stable phenomena in the universe we observe around us.

After that last "matter of fact" factual" "straight down the line" "tell it as it is"post previous to this one, I have no more to say.
I would just add that what was said about WH's, wormholes, and BH's, is the same case one must apply to time travel possibilities.
Another point re the Kerr-Newman type BH, a charged rotating BH, and also the plain old Kerr metric BH, is that regions called ergospheres are created from which escape is theoretically possible.
That seems to raise another possible method of time travel.

 

[brucep]

That's certainly one way of looking at the statement, I suppose.


Farsight created this thread so he could preach the good news and report anybody who disagreed with him. Others sought to discuss the matter with Farsight, much to their own folly. The OP isn't typically interested in having discussions with people unless they agree with him, it's a pattern of behaviour that's been playing itself out since at least 2007 across multiple internet fora - I participate in two other fora (as a chatter) from which he has been permanently banned precisely because of this pattern of behaviour and the disruption his evangelical preaching causes.

On the other hand, in any given discussion on a public medium neccessarily stretches across multiple levels of understanding and expertise, sometimes establishing the level of understanding of your interloqutor is neccessary for reasonable discourse to occur - after all, offering you explanations, examples, and opinions that are manifestly over your head is as much a waste of your time as it is mine, correct?

Finally, do you not see a moral or philosophical objection to evangelical opposition to something you do not understand? I use the word evangelical here because it seems an approriate word to use when someone uses phrases like 'starry eyed' and starts talking about science as a faith in an effort to try and disparage explanations they do not like and can-not otherwise attack.


Nonsense. There is one correct answer to the question. Then there are a bunch of conjectures as to why that correct answer may not be realistic or feasable, and some more conjectures as to why thos conjectures may themselves be flawed meaning that the original answer may be feasable after all.


They're not speculation. The existence of faeries is speculation, the existence of unicorns is speculation.

Blackholes, whiteholes, and wormholes are theoretical predictions that are made as solutions to the einstein field equations and various space-time metrics, each of which has theoretical reasons, many based on these same solutions, as to why they may not be stable phenomena in the universe we observe around us.


Yes, I say physics as we understand it, I even talk about physics as I understand it.

Look, the simple fact of the matter is that everybody who has ever actually studied relativity and quantum mechanics knows that both theories are incomplete, we know this because they have mutually exclusive views of how space-time works. This is why we research things like string theory and loop quantum gravity - because they provide solutions for this problem that do not exist in modern physics, and provide us with a quantum theory of gravity. This is why we use astronomical observations to test relativity in increasingly extreme environments - in the hope that we might detect some deviation between relativity and reality that might point the way to what will replace it.

Do white holes exist? We don't know. At this point they remain a prediction of relativity that, as far as we know anyway, has yet to be oserved, however, their observation has implications because there are some solutions that predict we shouldn't see them in this universe, and that their observation in this universe has implications regarding the stability of black holes.

Do wormholes exist? We don't know. At this point, if they do exist we don't expect them to look like the schwarzchild solution because we don't expect to see whiteholes in this universe. Then again, maybe the multiverse theory is correct and they behave exactly as the schwarzchild metric predicts but they connect to some other, very different place.

Do blackholes exist? Almost certainly, there's far too much observational evidence that suggests their existence, and much of that evidence points to the kerr-newman rotating blackhole as being the best model this side of the event horizon. What lies inside the event horizon? We don't know. Relativity, combined with particle physics predicts a singularity of zero size. I've always been of the understanding that this is just, in essence relativities way of saying "Nope, fuck that shit, you're on your own here" and that relativity is expected to break down somewhere inside the event horizon and be replaced by something else that we don't have yet. This is where things like loop-quantum gravity or string theory come in.

At least, as I understand it.


Are you a creationist? This kind of rhetoric sure makes you sound like one. If you want to discuss the moral and philosophical implications and meanings of 'truth' then we have a subforum or two just for that, thihs one, however, is physics and math.


Or maybe I have and you've just been too busy delving into the mucky-muck to notice.

There should be a law restricting how much intellectual dishonesty members get to darken the doorstep of this forum with. What Farsight does is the WORST trolling possible. It must be ok with all those that continue to engage his purposely illiterate comments and those who allow it to continue without consequence.

 

[Beer w/Straw]

No wait. Landau was right.

http://theinfosphere.org/Church_of_Trek

 

[Landau Roof]

brucep, Trippy -I appreciate the effort you are making on my behalf as well as for whoever else cares to read your thoughtful post. Know that I am reading and considering well all that you have said. I will respond if and when I have something to say. Thank you.

 

[Dr_Toad]

There should be a law restricting how much intellectual dishonesty members get to darken the doorstep of this forum with. What Farsight does is the WORST trolling possible. It must be ok with all those that continue to engage his purposely illiterate comments and those who allow it to continue without consequence.

Given that, why is this thread still in Physics & Math, instead of the Cesspool?

 

[Beer w/Straw]

I've got a feeling Farsight wont be around for awhile.

Maybe someone will ponder a question in the meantime.

 

[Farsight]

Ah, so someone who works with computers who has no credentials as a physicist.

Yep. That's me.

Right. I am sure you are worshipped as much as Joseph Le Conte was.

No I'm not. It's just that as an IT guy I have a good training in analysis and logic, and there are professional physicists who have commented favourably about that.

He was a natural historian and an amateur engineer; I am sure he thought that many engineers of his time considered HIM to be the expert. His claim that man would never fly is as valid as your claims that man will never travel through time.

The guy was talking patent pompous popscience nonsense because birds flew, men had flown in a balloon a hundred years previously, and there were already internal combustion engines around.

Let's hope you can get over to the UK and straighten Hawking out one of these days. I am sure you would find the experience . . . illuminating.

I live in Poole in the UK. And honestly, whilst Hawking is a media darling, he is not well thought of by physicists. Have a read of this physicsworld article:

"This morning there was lots of talk about science on BBC Radio 4′s Today programme – but I think it left many British scientists cringing under their duvets.
Stephen Hawking was on the show explaining why M-theory – an 11-dimensional structure that underlies and unifies various string theories – is our best bet for understanding the origin of the universe. Hawking explained that M-theory allows the existence of a “multiverse” of different universes, each with different values of the physical constants. We exist in our universe not by the grace of God, according to Hawking, but simply because the physics in this particular universe is just right for stars, planets and humans to form. There is just one tiny problem with all this – there is currently little experimental evidence to back up M-theory. In other words, a leading scientist is making a sweeping public statement on the existence of God based on his faith in an unsubstantiated theory."

 

[Farsight]

So I'm having my morning coffee and checking my forum alerts and opening a few other tabs off-forum when I see this: Time Travel Is Real. Here Are the People and Spacecraft Who Have Done It
All right. I'm very opened-minded, or like to suppose I am, so I click the link... and it's good that I did because, guess what, the headline is a totally misleading bit of the old bait and switch routine. If you care to click the link, you will see that it's a Wired.com light pop-sci piece about time dilation. For those who have been following this thread and refuse to accept that time dilation is not time travel, this article ought to show you how travel and dilation differ.

Good stuff Landau. Sadly people do so love their woo. They lap it up, and they cling to it in the face of all the logic and evidence you show them.

...I think Farsight's got it right, and yes, I blame Star Trek and this faith in science that many of our friends have for accepting every 'neat' sci-fi idea as something that WILL come to pass, and make us happy and well, and oh so totally cool. I know. People thought we'd never fly or have telephones, but these achievements are of a whole nother order of things we can't possibly achieve, Travel back in time! Only think! The very phrase is nonsensical. All of us over age 12 have regrets, and wish we could turn back the clock, but it just ain't gonna happen What we should be discussing is how to make amends for all the asshat things we've all done, and do our best to improve. It's all about morals, I think. If we could only decide to be good, and somehow stick to it, we wouldn't need to go to Mars or the restaurant at the end of the universe or 'boldly go where no man has gone before'. We don't need to turn back the clock. What we need is the strength to be righteous and never falter. However, we're mere men and women, and we will weaken and screw up sooner or later. Dreaming of time travel changes nothing.

More good stuff.

 

[Farsight]

You might find this interesting. I'll list three examples in response to comments you made in your post. The first is the relativistic rocket. The example is theoretically possible if we could solve some huge technological problems. At g_earth constant acceleration for 1/2 the journey and constant g_earth deceleration over the 2nd 1/2 of the journey we could reach the Andromeda Galaxy in 28 years measured on the ships clock. Measured on the Earth clock 2 million years would pass. So if the rocket crew turned around and came back to Earth 4 million years would have passed since the rocket started the journey.

Yes, time dilation is real. But the crew travelled through space, not through time. They could achieve the same effect by spending four million years in a stasis box, which is a glorified refrigerator. They aren't time travelling, they are suffering less internal motion, that's all. It's like I said in the OP, you "travel" to the future by not moving at all whilst everything else does.

The 2nd example would be for the GPS. Derived by modeling the near earth spacetime with Schwarzschild coordinates. The formula is [12] in QUERY 8. For the GPS the satellite clock ticks faster [infinitesimal] than the clock on the surface of the earth...

Landau has already said time dilation is not time travel.

...This following example uses the time travel equation in a way which might be interesting to you. Note that the time intervals dTau and dt are different but that they both measure time intervals as recorded by a clock in a specific coordinate system. dt for Earth and dTau for the spaceship orbiting the black hole...

A clock "clocks up" local motion inside the clock. When one clock is going slower than another, the motion is going slower, that's all. When you're time-dilated it's like you're living your life in slow motion. But you aren't time travelling.

 

[Farsight]

Farsight created this thread so he could preach the good news and report anybody who disagreed with him.

No, I created this thread in order to challenge woo, and as a lead-in to another thread on the speed of light which is a lead-in to an explanation of how gravity works. I don't report people who disgree with me, I report people who are abusive and offensive and who seek to trash threads and spoil the forum.

Others sought to discuss the matter with Farsight, much to their own folly. The OP isn't typically interested in having discussions with people unless they agree with him, it's a pattern of behaviour that's been playing itself out since at least 2007 across multiple internet fora - I participate in two other fora (as a chatter) from which he has been permanently banned precisely because of this pattern of behaviour and the disruption his evangelical preaching causes.

That's not true. I make a case for the subject of discussion, with references, and the idea is that you offer a counter-argument to show where I'm wrong. If you can't, you yield graciously. When I've been banned it's typically because there's some "moderator" who thinks he's the expert and who can't bear to be shown to be wrong by a guy like me. If you'd like to refer to another forum I can show you my posts there. They will be civil, concerning physics. And other posts will probably demonstrate that the moderator gives free rein to abusive trolls who seek to trash the thread.

They're not speculation. The existence of faeries is speculation, the existence of unicorns is speculation. Blackholes, whiteholes, and wormholes are theoretical predictions that are made as solutions to the einstein field equations and various space-time metrics, each of which has theoretical reasons, many based on these same solutions, as to why they may not be stable phenomena in the universe we observe around us.

But the level of speculation varies. There's virtually no speculation concerning black holes: we know there's something very small and very massive in the centre of our galaxy. However there is no evidence whatsoever for white holes or wormholes, or for time travel.

Are you a creationist? This kind of rhetoric sure makes you sound like one. If you want to discuss the moral and philosophical implications and meanings of 'truth' then we have a subforum or two just for that, thihs one, however, is physics and math.

The people who believe in things like time travel despite all the evidence of what clocks do and what time is, are the people behaving creationists.

 

[Dr_Toad]

It's just that as an IT guy I have a good training in analysis and logic, and there are professional physicists who have commented favourably about that.

Now I know you're a liar, and not just a self-deluded narcissist.