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5351 clicks; posted to Geek » on 07 May 2012 at 3:27 AM   |  Favorite    |   share:    more»

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For the benefit of all those wondering how time travel and faster than light travel relate to each other, it works something like this:

We define our reality in terms of 4 dimensions - x, y, z, and t. This 4 dimension system is called space-time, and it encapsulates more or less every practical aspect of daily life. The funny and unique thing about spacetime is that you move through it at a constant rate, no matter what or where you are (a fact that would render GPS navigation incapable of working if unaccounted for). This bears some interesting consequences - if you were to stand still in space, you would be moving through time at the maximum possible rate since your movement through the other 3 dimensions is 0. Likewise, as you move through space, there is less and less room in the space-time equation for movement through time. This is time dilation - it actually happens everywhere all the time, but near-lightspeed is when it becomes relevant. If you move at the maximum speed - the speed of light - you are not moving through time at all. By simple arithmetic, this can be extrapolated to mean that if you went beyond the speed of light, you would have to move through negative time in order to be moving through spacetime at the same constant rate as anything else. There's a much more interesting and complicated explanation, but that's the long and short of it.

Fun Fact: Photons do not experience time at all. From their frame of reference, they are generated in the sun and disperse over your skin in the same instant. Also, if an object is not created at the speed of light, it can never attain the speed of light due to the fact that, at some point in time, it wasn't already at the speed of light. Time literally has no meaning on objects moving that fast.

The Alcubierre Warp drive cheats this restriction by not actually moving the spaceship/bullet/cargo unit through physical space. Instead, the ship is merely surfing a rippling wave of spacetime itself - from the perspective of the passengers, there would be no acceleration or any physical evidence whatsoever of the distance traveled. In addition, since the ship has been more or less sitting still this entire time, there wouldn't be any time dilation.

Someone made note of the fact that the energy dissipating from this form of travel is extremely destructive - I remember reading that same article, but remember that the mathematical simulation was only accounting for a 2D slice of the space around the arriving spaceship, so the problem may still be circumvented by "gating in" a bit to the left of your actual destination.

darthmarth28: For the benefit of all those wondering how time travel and faster than light travel relate to each other, it works something like this:

We define our reality in terms of 4 dimensions - x, y, z, and t. This 4 dimension system is called space-time, and it encapsulates more or less every practical aspect of daily life. The funny and unique thing about spacetime is that you move through it at a constant rate, no matter what or where you are (a fact that would render GPS navigation incapable of working if unaccounted for). This bears some interesting consequences - if you were to stand still in space, you would be moving through time at the maximum possible rate since your movement through the other 3 dimensions is 0. Likewise, as you move through space, there is less and less room in the space-time equation for movement through time. This is time dilation - it actually happens everywhere all the time, but near-lightspeed is when it becomes relevant. If you move at the maximum speed - the speed of light - you are not moving through time at all. By simple arithmetic, this can be extrapolated to mean that if you went beyond the speed of light, you would have to move through negative time in order to be moving through spacetime at the same constant rate as anything else. There's a much more interesting and complicated explanation, but that's the long and short of it.

Fun Fact: Photons do not experience time at all. From their frame of reference, they are generated in the sun and disperse over your skin in the same instant. Also, if an object is not created at the speed of light, it can never attain the speed of light due to the fact that, at some point in time, it wasn't already at the speed of light. Time literally has no meaning on objects moving that fast.

The Alcubierre Warp drive cheats this restriction by not actually moving the spaceship/bullet/cargo unit through physical space. Instead, the ship is merely surfing a rippling wave of spacetime itself - from the per ...

OMG photons are really smart aliens!

Baron Harkonnen: To the observers at my destination point, I would be existing at two different places at the same time, and not only that, I could potentially interact with my own self at an earlier point in time, creating any number of unresolvable paradoxes.

The observers might think that, but you shoudn't, unless you are light itself.

Baron Harkonnen: Because People in power are Stupid: At some point -some physicist physics student convinced me that time wasn't the same everywhere and that if we went faster than the speed of light then we would move backwards in time.

I've heard the same. I was hoping the question of faster-than-light travel would come up on Fark, so I could have the possibility of someone smarter than I answering the question.

Whether or not FTL is possible is besides the point. We'll assume that it is. I was told that when an object goes faster than the speed of light, it interacts at with photons and gravity waves at an earlier state in time, which is the difference in light-seconds between how fast the object is traveling and the speed of light. So, if I travel one light-day out in a single second, I'm interacting with light and gravity that's one day old minus one second. And, by logical extension, I'm not only interacting with yesterday's light and gravity, I'm interacting with anything affected by light or gravity. Which is everything. I just time traveled one day in the past.

Time travel opens up nasty unsolvable causality paradoxes which can endlessly duplicate matter and energy at a net gain, and completely defeat entropy. Which is basically the universe saying that you just divided by zero. I could take my fancy spaceship 8 light-years to Tau Ceti 8 years in the past, spend the weekend there, then zip back to Earth, once again traveling eight years in the past to 16 years ago, walk up to my previous self, and tell him that Tau Ceti is a dump and not to go there 16 years in the future. So, past me doesn't go. And with that notion, I can duplicate myself infinite times via paradox like Bender in Futurama. Potentially infinite mass and energy from nowhere.

I'd be interested to hear someone who knows physics enough to know what they're talking about reply to this. It's been a nagging question about physics I've had for a long time.

As a person who does physics, I'll jump in here.

With our current math, you basically divide by zero if you're going faster than the speed of light. m^2 becomes negative, m becomes a complex number, etc etc.

If FTL travel were possible, you would basically need to rewrite everything we know, while still having a theory that's self consistent and matches our current observation of STL travel. Currently though, even saying, "this thing is traveling 1.5C" breaks a LOT of things.

That being said, there are some attempts at consistent FTL travel theories, some of which got really popular in the bit of time that people thought neutrinos were going the speed of light. One in particular I read up a little bit about says that tachyons could break causal relations, but you couldn't transform reference frames across the light-cone. I.E. FTL and STL stuff can't swap to be each other.

TL;DR: Asking how FTL travel works gives you an AnswerNotFound exception because our current theories break hard once things are going faster than light, but some people have some interesting guesses in the, "If it can happen, it might look like this" sort of way

Time is the simplest thing

Baron Harkonnen: Bacon Bits: That's idiotic. You're also simultaneously interacting with light that won't reach you for one day, so by this same logic you're simultaneously travelling [sic] one day into the future.

You'll have to explain what's idiotic to me, because your logic escapes me. You're correct in that I would be traveling one day into the future as observed from the opposite direction of my travel. Observers would see me blink out and then re-appear 24 hours later in a location one light-day more distant. But time-traveling to the future does not create paradoxes, and is allowed by physics. In the direction I'm heading, I'd be observed to have arrived a day earlier than I departed, because the light of my spacecraft departing would take a day to arrive from my departure point, and in the meantime, I would have been at my destination for that entire day. To the observers at my destination point, I would be existing at two different places at the same time, and not only that, I could potentially interact with my own self at an earlier point in time, creating any number of unresolvable paradoxes.

Light != Time
Appearing to be in two places does not mean you are in two places. It just means that light that bounced off of you from two different locations in arriving at one destination at the same time. That doesn't mean that you can communicate with that you that you're seeing.

Because People in power are Stupid: I don't really understand this.

At some point -some physicist physics student convinced me that time wasn't the same everywhere and that if we went faster than the speed of light then we would move backwards in time. This is saying something different.

If all we needed was antimatter -according to this -all we need to do is figure out how to collect it from the Van Allen radiation belt.

The flow of time is relative to the observers speed. So you set off in your warp capable ship and go FTL for ohh... a day? Enough to go visit our nearest solar neighbour. Upon your return 200 years has passed for us on Earth but for you only two days (travel) plus whatever you'd spent sightseeing would of passed. Those are figures out of my ass I should add but no, time would not flow backwards the difference would just keep getting bigger so a day at X = Y time passed on Earth.

It does however mean that any excursion beyond light speed, without airy-fairy sub-space tunnelling/space folding shenanigans in-between, of any respectable distance... would mean everyone you knew and loved died the instant you pushed the big red button marked "Go biatch go".

Antimatter was, last I heard, pretty rare in nature. So once you've got your ram scoop and magnetic bottles to contain it, you'd be up there for a decade (if not more) fuelling up. OTOH I'm not totally sure loading 100Kg of AM on to a chemical rocket would be all that sensible either.

czetie: Actually, in Special Relativity, if an object could exceed the speed of light (c), it wouldn't move backwards in time so much as "sideways".

tl;dr: In Special Relativity, the dimension of time behaves pretty much like an extra space dimension except that it's imaginary (in the mathematical, not literal sense). If you could somehow get a particle past the barrier of infinite energy at v=c, and take the equations of SR at face value, you find that time becomes a regular space dimension, and the space dimension in the direction of travel becomes the new time. Neat, no?

Strictly speaking, Lorentz transformations of spacelike particles (if they behave the same way) will let you "boost" into the past.

A warp drive gets around the problem by not accelerating at all, and instead, manipulates the region of spacetime around the craft.

/ approves
// the spice must flow

darthmarth28: Someone made note of the fact that the energy dissipating from this form of travel is extremely destructive - I remember reading that same article, but remember that the mathematical simulation was only accounting for a 2D slice of the space around the arriving spaceship, so the problem may still be circumvented by "gating in" a bit to the left of your actual destination.

The problem with the Alcubierre hypothesis isn't the energy dissipation at the end, it's that establishing the warp bubble takes more energy than exists in the known universe.

darthmarth28: The Alcubierre Warp drive cheats this restriction by not actually moving the spaceship/bullet/cargo unit through physical space. Instead, the ship is merely surfing a rippling wave of spacetime itself - from the per ...

This is what I've always understood - warp drives aren't going past the speed of light, but warping space so that at sub-light speeds, an outside observer would see you arrive in less time that light would take to arrive.

......

Food for thought on the subject of time paradox that others have been talking about - if you think about it, a paradox exists for any possible piece of information that travels back in time even the smallest possible bit of information.

Let's say you use a time machine to send a textbook on general relativity to Einstein before he invented it. Assuming he actually uses it, he won't have to invent GR at that point. It has become information with no creator, which means it never existed in the first place, which means Einstein could have invented it, etc.

You can take that scenario and keep reducing it to smaller bits of information. So in essence, it seems to be that anything which goes back in time creates a paradox, let alone the relatively complex grandfather paradox scenario.

Femtoseconds? We didn't have this problem back in the 50s, damn women's libbers.

Interestingly enough, there is a limit to how much spacetime can be warped under M-theory. These physicists found that the ultimate warp speed limit is 1032C - or roughly 3.3 trillion trillion light years per second, and would require 1031J of energy. This speed is so fast, you could travel to the edge of the visible universe (14 billion light years) in 4.4 femtoseconds.

And under Sting Theory, there's a shadow on the door of a cottage near the shore of a dark Scottish Loch.

"The string theorists have a theory that appears to be consistent and is very beautiful, very complex, and I don't understand it. It gives a quantum theory of gravity that appears to be consistent but doesn't make any other predictions. That is to say, there ain't no experiment that could be done nor is there any observation that could be made that would say, 'You guys are wrong.' The theory is safe, permanently safe. I ask you, is that a theory of physics or a philosophy?"

-- Sheldon Glashow, Ph.D., Arthur G.B. Metcalf Professor of Physics at Boston University and winner of the 1979 Nobel Prize in Physics

BigSlowTarget: So with 0.0000001 kg of antimatter could I prove string theory by creating a warp big enough for a single particle? It seems to me if there was any validity to this new 100kg theory that would be big news.

One of the problems with string theory is scientists haven't come up with a way to test it. So if we build a warp drive, we can test string theory? Kill two birds with one stone!

meanmutton: "The string theorists have a theory that appears to be consistent and is very beautiful, very complex, and I don't understand it. It gives a quantum theory of gravity that appears to be consistent but doesn't make any other predictions. That is to say, there ain't no experiment that could be done nor is there any observation that could be made that would say, 'You guys are wrong.' The theory is safe, permanently safe. I ask you, is that a theory of physics or a philosophy?"

-- Sheldon Glashow, Ph.D., Arthur G.B. Metcalf Professor of Physics at Boston University and winner of the 1979 Nobel Prize in Physics

The attitude that we should just reject it because some pieces of it are currently untestable is foolish and short-sighted. String theory makes predictions and some can be tested and some bear out. That other pieces seem immune to the rigors of classical science may just be a temporary problem caused by a still-limited understanding of what's happening, and we shouldn't just abandon decades of work on the possibility that it may remain unknowable.

Really? I have to do this?

And Newton's gravitational theory says that it should take no work to walk from San Francisco bay to NY harbor. They are, after all, both at sea level and thus there's not gravitational energy difference.

//What I'm saying is that the engineering steps can be kind of important.

As you approach the speed of light, spatial dimensions contract. So if you're traveling from Earth to Alpha Centauri (both moving relatively slowly compared to each other) at close to the speed of light, the people on Earth see you take about 4 years to get there (rounding for simplicity) -- precisely what you'd expect.

On the ship, however, the closer you get to the speed of light, the shorter that distance is. Not looks. Is. Let's say it takes you a year from your frame of reference. So when you slow down and take a look around, you've taken a four year journey in a year -- Alpha Centauri and Earth have both experienced 4 years in their reference frame.

The equations that describe these things work extremely well. You might say they're what really happens. The problem is that they use the gamma coefficient, which is defined as 1/( sqrt(1 - (v/c)^2) ).

So when your velocity equals the speed of light, the equations are undefined, because you have to divide by zero. If velocity is greater than the speed of light, the answer is complex (square root of a negative number -- imaginary, if you want).

So the equations are correct (no lightspeed or faster travel) or incomplete (funny stuff happens at the boundaries, or there's a way to cheat relativity).

Hang on a second. Loop quantum gravity clearly offers more testable predictions than string theory.

Tyrone Slothrop: And under Sting Theory, there's a shadow on the door of a cottage near the shore of a dark Scottish Loch.

Stig Theory? Some say he can go to the loo in 4.4 femtoseconds...

Splinshints: meanmutton: "The string theorists have a theory that appears to be consistent and is very beautiful, very complex, and I don't understand it. It gives a quantum theory of gravity that appears to be consistent but doesn't make any other predictions. That is to say, there ain't no experiment that could be done nor is there any observation that could be made that would say, 'You guys are wrong.' The theory is safe, permanently safe. I ask you, is that a theory of physics or a philosophy?"

-- Sheldon Glashow, Ph.D., Arthur G.B. Metcalf Professor of Physics at Boston University and winner of the 1979 Nobel Prize in Physics

The attitude that we should just reject it because some pieces of it are currently untestable is foolish and short-sighted. String theory makes predictions and some can be tested and some bear out. That other pieces seem immune to the rigors of classical science may just be a temporary problem caused by a still-limited understanding of what's happening, and we shouldn't just abandon decades of work on the possibility that it may remain unknowable.

Economists have a term for that.

Sgygus: the ultimate warp speed limit is 1032C - or roughly 3.3 trillion trillion light years per second ... so fast, you could travel to the edge of the visible universe (14 billion light years) in 4.4 femtoseconds

.

The article gets it wrong, the distance to the edge of the observable universe is in the 46-47 billion light-years range. The AGE of the universe is 13.7 billion years but space has expanded in that time.

Observable Universe

dready zim: So just to be clear, you can travel 4 light years in much less than 4 years but you can`t go faster than the speed of light.

Relatively speaking, yes.

ArcadianRefugee: Under String Theory, a real life warp drive would only require 100kg of anti-matter

Wow. I used to think we'd require a spaceship with engines. Turns out all we need is a stockpile of antimatter, which we can produce at about 250 nanograms each year.

And it will only require 1 billion years of the energy production of the entire Earth.

Interstellar travel, here we come!

Meh, we will just outsource antimatter production to China and purchase the finished product from them. I'm sure a billion Chinese peasants can ramp that production up to 1 gram a year.

Epicedion: The equations that describe these things work extremely well. You might say they're what really happens. The problem is that they use the gamma coefficient, which is defined as 1/( sqrt(1 - (v/c)^2) ).

So when your velocity equals the speed of light, the equations are undefined, because you have to divide by zero. If velocity is greater than the speed of light, the answer is complex (square root of a negative number -- imaginary, if you want).

It could very well be Special Relativity is yet another approximation, just like Newton's laws were before them. The reason why the question is open is because there is no proof that FTL travel is physically impossible, and that's because SR is defined (if "imaginary") for v > c. While the equation works well for we've observed, the math we've established at this point does not disprove FTL.

This is where laymen get all excited for no good reason. Reality is complete; the math isn't. It's far more likely the equations needs revision than FTL travel is possible, but there are two factors to consider:
1) Since v > c corresponds to no known particles with mass and is technologically impossible for the foreseeable future, there's no hurry to update the equation to explain phenomena that haven't been observed, and
2) There isn't any defined Law of Conservation of Causality, so scientifically the anti-FTL crowd has only lack of evidence to go on. Which isn't the sort of thing that prevents science from trying.

So we have an arguably incomplete equation that allows for FTL travel on some wonky level and scientists rigorously testing that incompleteness. The media thinks this means we're trying to develop FTL when it's far more likely everyone thinks FTL is impossible and they're just trying to improve the math. Improving one of Einstein's famous equations is a real feather in any physicist's cap, and the best way to improve an equation is to try to break it.

So, all we need to do is understand gravity because you'd need local gravity right? Is the idea you speed "up to" the speed of light incrementally or is Newtons laws of motion irrelevant within a warp field?
And what happens to the casual radiation of space you pass through? If you "speed up to" the speed of light and let's say you pass through a band of radio waves, since you're moving faster than they are what happens to the radiation you pass through. Do you absorb so much energy you explode or die in a gamma ray burst? And what happens to solid objects when they meet a warp field. If you're warping along and you suddenly run into an object the size of a pea, what happens? I get the idea that time is irrelevant, because time doesn't exist to start with. Atrophy exists, not time. And speaking of gravity, how do objects react in a warp field. Do the laws of quantum mechanics and Einstein space apply within the field itself, or is their some sort of change because you're outside of the normal space/time? And I guess everything would go black as soon as you jumped to light speed since you're now traveling faster than light.
I could go on, but I think space travel is a great mind experiment. That's all. I can't see it ever coming to your nearest space port anytime soon.

Nogrhi: GAT_00: They worked out that under string theory, a warp drive would no longer require exotic matter, and the required energy would be roughly 100kg of antimatter (1019J) to warp the space around a ship the size of the space shuttle.

Well, I'm sure we'll never need a larger ship than that.

Not if you get to the edge of the visible universe in 4.4 femtoseconds.... I think we have time to make a few trips.

The space shuttle's a pretty cool design in terms of what it can do when it gets where it's going. The cargo bay can hold almost anything and the robot arm and spacewalking astronauts can do almost anything. Trouble was it was too heavy to push beyond low earth orbit. A warp drive would take care of that, especially if it didn't have to take any room in the cargo bay - something like the hyperdrive ring for Obi-Wan Kenobi's Jedi fighter. An external warp drive stage could also contain power and consumables to extend the shuttle's mission duration, similar to the EDO pallet and SSPTS.

Nogrhi: Well, I'm sure we'll never need a larger ship than that.

Not if you get to the edge of the visible universe in 4.4 femtoseconds.... I think we have time to make a few trips.

Then suddenly a clue turned up in Scotland. Mr Angus Podgorny, owner of a Dunbar menswear shop, received an order for 48,000,000 kilts from the planet Skyron in the Galaxy of Andromeda.

[Mix to interior of highland menswear shop. An elderly Scottish couple are poring over a letter which they have on the counter. Oil lamps etc.]

Mrs Podgorny: Angus how are y'going to get 48,000,000 kilts into the van?

Angus: I'll have t'do it in two goes.

Mrs Podgorny: D'you not ken that the Galaxy of Andromeda is two million, two hundred thousand light years away?

Angus: Is that so?

Mrs Podgorny: Aye ... and you've never been further than Berwick-on-Tweed...

Angus: Aye ... but think o' the money dear ... £18.10.0d a kilt ...that's ... (calculates with abacus) £900,000,000 - and that's without sporrans!

Mrs Podgorny: Aye ... I think you ought not to go, Angus.

Angus: (with visionary look in his eyes) Aye ... we'd be able to afford writing paper with our names on it... We'd be able to buy that extension to the toilet...

Mrs Podgorny: Aye ... but he hasn't signed the order yet, has he?

Angus: Who?

Mrs Podgorny: Ach ... the man from Andromeda.

Angus: Och ... well ... he wasna really a man, d'you ken ...

Creepy music starts to edge in.

Mrs Podgorny: (narrowing eyes) Not really a man?

Angus: (sweating as the music rises) He was as strange a thing as ever I saw, or ever I hope to see, God willing. He was a strange unearthly creature - a quivering, glistening mass...

Mrs Podgorny: Angus Podgorny, what do y'mean?

Angus: He wasna so much a man as... a blancmange!

[Jarring chord.]

Hoo boy, where to start here. First, I guess, is the fact that the spaceship using this "Warp Drive" is not itself moving. It is moving space around it, so there is never any incremental rise to lightspeed or any worry about impacts with space debris. If anything, the Warp Field may just pick space dust up and carry it with you - I think that's the thing that obliterates whatever you stop in front of at the end of your trip. There wouldn't be any reason why Newtonian mechanics would goof up inside the Warp Field, since the region your ship is sitting in is perfectly normal Space-time. It's the area directly in front and behind you that are going to be weird.

Also, time does exist - it is exactly as real as "up" and "down" are, which is to say it's pretty integral to the fabric of reality. Time Dilation just wreaks merry hell with it. To be fair, though, it does just as much weirdness to space - there's no good reason why we don't call it "space dilation".

As for what it would look like... that's one of the coolest damn thoughts I've had all morning. I've got no idea.

hogans: Nogrhi: Well, I'm sure we'll never need a larger ship than that.

Not if you get to the edge of the visible universe in 4.4 femtoseconds.... I think we have time to make a few trips.

Then suddenly a clue turned up in Scotland. Mr Angus Podgorny, owner of a Dunbar menswear shop, received an order for 48,000,000 kilts from the planet Skyron in the Galaxy of Andromeda.

[Mix to interior of highland menswear shop. An elderly Scottish couple are poring over a letter which they have on the counter. Oil lamps etc.]

Mrs Podgorny: Angus how are y'going to get 48,000,000 kilts into the van?

Angus: I'll have t'do it in two goes.

Mrs Podgorny: D'you not ken that the Galaxy of Andromeda is two million, two hundred thousand light years away?

Angus: Is that so?

Mrs Podgorny: Aye ... and you've never been further than Berwick-on-Tweed...

Angus: Aye ... but think o' the money dear ... £18.10.0d a kilt ...that's ... (calculates with abacus) £900,000,000 - and that's without sporrans!

Mrs Podgorny: Aye ... I think you ought not to go, Angus.

Angus: (with visionary look in his eyes) Aye ... we'd be able to afford writing paper with our names on it... We'd be able to buy that extension to the toilet...

Mrs Podgorny: Aye ... but he hasn't signed the order yet, has he?

Angus: Who?

Mrs Podgorny: Ach ... the man from Andromeda.

Angus: Och ... well ... he wasna really a man, d'you ken ...

Creepy music starts to edge in.

Mrs Podgorny: (narrowing eyes) Not really a man?

Angus: (sweating as the music rises) He was as strange a thing as ever I saw, or ever I hope to see, God willing. He was a strange unearthly creature - a quivering, glistening mass...

Mrs Podgorny: Angus Podgorny, what do y'mean?

Angus: He wasna so much a man as... a blancmange!

[Jarring chord.]

CRIVENS!!!

dragonchild: Epicedion:It could very well be Special Relativity is yet another approximation, just like Newton's laws were before them. The reason why the question is open is because there is no proof that FTL travel is physically impossible, and that's because SR is defined (if "imaginary") for v > c. While the equation works well for we've observed, the math we've established at this point does not disprove FTL.

This is where laymen get all excited for no good reason. Reality is complete; the math isn't. It's far more likely the equations needs revision than FTL travel is possible, but there are two factors to consider:

I guess you mentioned it, but just to expound a little on what you said, physics theories are special cases of a higher all-encompassing theory. E.g. relativity can be reduced to Newtonian physics if you tweak certain "input" parameters to the framework of the theory. We know from experiments that relativity is ultra-accurate in it's domain. Also from experiments we know that Newtonian physics is ultra-accurate in it's domain. Since relativity encompasses Newtonian physics, it's very very likely that the "next" theory will be an extension to relativity, or maybe a partner theory to relativity within a more general framework.

tldr: Relativity and Newtonian physics will never ever go away even if we figure out the TOE. They are badass, immortal theories if you use them in the right places.

ChaoticLimbs: 100Kg of antimatter is a lot of antimatter. I guess if we ever make antiiron you could keep it in solid state and in a magnetic field, but gaseous antimatter in that kind of quantity is going to be impossible to contain.

Also, isn't 100Kg of antimatter roughly equivalent to about 20 nuclear warheads in the megaton range?

4300 megatons if wikipedia is to be believed. I was expecting a much larger number.

dragonchild: There isn't any defined Law of Conservation of Causality

It is taken as a law, even if it's not formally defined as such, like Conservation. Even the Law of Conservation is taken as true because we don't have any countervailing evidence and a lot of stuff would stop making sense if it weren't.

Causality pretty much falls into the same bucket: effects might precede causes, but if that were true, the universe would look very different than it does now.

It is worth noting that entanglement can happen in atemporal fashions. It's not so much that causes proceed the effects, as much as the details of the cause can be dependent upon the effect.

darthmarth28: Time Dilation just wreaks merry hell with it.

I'd disagree, slightly. Time dilation wreaks merry hell with our understanding of time. From a physical perspective, the effects of time dilation are pretty simple and easy to understand. It's just exceedingly counter-intuitive because our brains didn't evolve to act at significant proportions of the speed of light.

Relativity simply tells us that temporal relationships, like spatial relationships, are a function of the reference frame doing the measuring, and might not reconcile consistently across reference frames.

nmiguy: Interestingly enough, there is a limit to how much spacetime can be warped under M-theory. These physicists found that the ultimate warp speed limit is 1032C - or roughly 3.3 trillion trillion light years per second, and would require 1031J of energy. This speed is so fast, you could travel to the edge of the visible universe (14 billion light years) in 4.4 femtoseconds.

There is no M-Theory. "M-Theory" is just a name for a theory we would like to have (but don't). People talk about M-Theory like it exists, but all we have of it is a notion of certain features we would like it to have. In fact, there is no fully formed string theory, only a lot of new results in mathematics that people have come up with trying to unify quantum mechanics with gravity.

It would take us thousands of years to generate 100kg of antimatter. May as well head to the stars the slow way.

FuturePastNow: It would take us thousands of years to generate 100kg of antimatter. May as well head to the stars the slow way.

I've been reading a really cool book lately, Centauri Dreams. He goes into the history and a little bit of detail about all kinds of methods we might use in the future for space travel. Fusion pellets...solar sails...antimatter engines...blowing up nukes...etc. Awesome book.

Shouldn't antimatter be measured in anti-kilograms?

indarwinsshadow: So, all we need to do is understand gravity because you'd need local gravity right? Is the idea you speed "up to" the speed of light incrementally or is Newtons laws of motion irrelevant within a warp field?
And what happens to the casual radiation of space you pass through? If you "speed up to" the speed of light and let's say you pass through a band of radio waves, since you're moving faster than they are what happens to the radiation you pass through. Do you absorb so much energy you explode or die in a gamma ray burst? And what happens to solid objects when they meet a warp field. If you're warping along and you suddenly run into an object the size of a pea, what happens?

My understanding, as a layperson who likes to read articles about this sort of thing, is that all the radiation / objects / whatever in your direct path gets scooped up in the spacetime warp and arrives with you at your destination. It then kills everything that's directly in front of you (on account of it being a nasty and impossibly condensed mix of radiation and matter and energy and what-have-you).

I remember, back in the 90's, when Hard Hittin' Ed Witten jacked 4 home runs, and had 12 RBI in the second game of a doubleheader at Cincinnati.
Is there anything this guy can't do?

Hoo boy, where to start here. First, I guess, is the fact that the spaceship using this "Warp Drive" is not itself moving. It is moving space around it, so there is never any incremental rise to lightspeed or any worry about impacts with space debris. If anything, the Warp Field may just pick space dust up and carry it with you - I think that's the thing that obliterates whatever you stop in front of at the end of your trip. There wouldn't be any reason why Newtonian mechanics would goof up inside the Warp Field, since the region your ship is sitting in is perfectly normal Space-time. It's the area directly in front and behind you that are going to be weird.

Also, time does exist - it is exactly as real as "up" and "down" are, which is to say it's pretty integral to the fabric of reality. Time Dilation just wreaks merry hell with it. To be fair, though, it does just as much weirdness to space - there's no good reason why we don't call it "space dilation".

As for what it would look like... that's one of the coolest damn thoughts I've had all morning. I've got no idea.

Good answers. Except the "time exists". Um, no it doesn't. Not to be a "nuh uh" guy, but you're model of time doesn't make any sense. Time isn't a physical entity. It's a happenstance of the human condition that we even notice "time". Time doesn't go from point a to b like a road. We call it time to differentiate the past from the present and future. But as far as an actual time, nope. It's not there. Entropy on the other hand makes sense since everything in existence now is slowly degrading and will eventually lose all energy to reach the zero state. Time, not so much. If you count time as measured by our brains and a clock, sure, time exists. As an actual thing. Nope. Distance sure, time nuh uh.

oh, and you've kind of nullified the point about passing through space in a warp field. There's that Einstein relativity thing creeping in. Point of view, observer see's you go by, you on the other hand see the observer go by. No matter what, you're moving from point A to B, so something is moving you or the universe. Either way, you pass through, along, or on it but either way. Somethings moving, and if you pass through a moving particle, or stationary particle either way somethings going to give up the energy from the higher state to the lower state.

indarwinsshadow: Time isn't a physical entity. It's a happenstance of the human condition that we even notice "time". Time doesn't go from point a to b like a road. We call it time to differentiate the past from the present and future. But as far as an actual time, nope. It's not there. Entropy on the other hand makes sense since everything in existence now is slowly degrading and will eventually lose all energy to reach the zero state.

Time is the progression of entropy, and it absolutely does exist. The way we perceive time is part of that progression.

I'm not even bothering with my usual screed here. Too many people with too much magic/TrekWars on the brain.

Man, why do people get things confused?
Even smart people.

Watch your definitions, know what you are trying to work with.

It's like they are trying to theorize or prove something based on an Abbot & Costello routine.

/who's on first?

indarwinsshadow: Time isn't a physical entity

Yes, it is. Our measurements of time are invented- seconds are as fictional as meters. But time, itself, definitely exists.

indarwinsshadow: We call it time to differentiate the past from the present and future.

You do realize you just said, "time doesn't exist, it exists." No one is claiming that time is a place you can go to. That's absurd. We're claiming that time is one of the four factors that differentiates an event in space-time. The others can vary depending on your coordinate system, but we usually use something cartesianesque- (x,y,z,t). That fourth coordinate is absolutely required to differentiate two events in spacetime- (1,1,1,0) is unique and distinct from (1,1,1,1).

hogans: Nogrhi: Well, I'm sure we'll never need a larger ship than that.

Not if you get to the edge of the visible universe in 4.4 femtoseconds.... I think we have time to make a few trips.

Then suddenly a clue turned up in Scotland. Mr Angus Podgorny, owner of a Dunbar menswear shop, received an order for 48,000,000 kilts from the planet Skyron in the Galaxy of Andromeda.

[Mix to interior of highland menswear shop. An elderly Scottish couple are poring over a letter which they have on the counter. Oil lamps etc.]

Mrs Podgorny: Angus how are y'going to get 48,000,000 kilts into the van?

Angus: I'll have t'do it in two goes.

Mrs Podgorny: D'you not ken that the Galaxy of Andromeda is two million, two hundred thousand light years away?

Angus: Is that so?

Mrs Podgorny: Aye ... and you've never been further than Berwick-on-Tweed...

Angus: Aye ... but think o' the money dear ... £18.10.0d a kilt ...that's ... (calculates with abacus) £900,000,000 - and that's without sporrans!

Mrs Podgorny: Aye ... I think you ought not to go, Angus.

Angus: (with visionary look in his eyes) Aye ... we'd be able to afford writing paper with our names on it... We'd be able to buy that extension to the toilet...

Mrs Podgorny: Aye ... but he hasn't signed the order yet, has he?

Angus: Who?

Mrs Podgorny: Ach ... the man from Andromeda.

Angus: Och ... well ... he wasna really a man, d'you ken ...

Creepy music starts to edge in.

Mrs Podgorny: (narrowing eyes) Not really a man?

Angus: (sweating as the music rises) He was as strange a thing as ever I saw, or ever I hope to see, God willing. He was a strange unearthly creature - a quivering, glistening mass...

Mrs Podgorny: Angus Podgorny, what do y'mean?

Angus: He wasna so much a man as... a blancmange!

[Jarring chord.]

SirTanon: a barry bit ay fin!

My nightmares have come true, I read that entire thing in the accent of my Uncle and Aunt.

/Mah heed is gonnae explode.

t3knomanser: indarwinsshadow: Time isn't a physical entity

Yes, it is. Our measurements of time are invented- seconds are as fictional as meters. But time, itself, definitely exists.

indarwinsshadow: We call it time to differentiate the past from the present and future.

You do realize you just said, "time doesn't exist, it exists." No one is claiming that time is a place you can go to. That's absurd. We're claiming that time is one of the four factors that differentiates an event in space-time. The others can vary depending on your coordinate system, but we usually use something cartesianesque- (x,y,z,t). That fourth coordinate is absolutely required to differentiate two events in spacetime- (1,1,1,0) is unique and distinct from (1,1,1,1).

No, I said it was a product of the calculation. People think of time as an object like a bug, or a piece of wood. It's not a thing. It's the end product.

Jubeebee: indarwinsshadow: Time isn't a physical entity. It's a happenstance of the human condition that we even notice "time". Time doesn't go from point a to b like a road. We call it time to differentiate the past from the present and future. But as far as an actual time, nope. It's not there. Entropy on the other hand makes sense since everything in existence now is slowly degrading and will eventually lose all energy to reach the zero state.

Time is the progression of entropy, and it absolutely does exist. The way we perceive time is part of that progression.

I'm not even bothering with my usual screed here. Too many people with too much magic/TrekWars on the brain.

Ok. Now prove it.

poot_rootbeer: Shouldn't antimatter be measured in anti-kilograms?

You're probably just joking, but in case you're not: no. Antimatter still has mass, momentum, is affected by gravity, etc. None of that stuff happens in a negative direction on anti-matter (compared to matter) or anything like that.

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