Forever420 on 23/9/2011 at 03:30

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And the stiffheads always have said it could not be done.

demagogue on 23/9/2011 at 05:34

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@Tocky, According to the book I just read (The Theory of Almost Everything), yeah all particles are wave/particle entities that race out according to quantum statistics, and under the Schwinger equations (apparently easier to describe than Feynman diagrams), you can think of every point in space, in the vacuum, with a potential for the particle to travel through it, but also particles can spontaneously be created and quickly annihilated in those points in the vacuum. Anyway, apparently all these points are originally like a harmonic oscillator in the math (like a marble rolling back & forth in a perfectly symmetric bowl), but some quirk (not quark) in the electroweak force breaks that symmetry (like a bump in the bowl that bounces the marble to one side) which lets certain particles able to hang around more than usual at those points, the Higgs bosons, and all other bosons can absorb the lopsided ones, which has the effect of crowding around them and bumping them around as they go through the vacuum, and you have to add energy to them if you want them to push through faster, which ends up acting like what we call "mass". (Whereas fermions don't interact with those bosons, so continue merrily along at C as if massless). And if you heated it up, at a point the symmetry doesn't break anymore all particles do indeed act massless. Or something like that. Google Higgs Mechanism.

...................................

Re: C
From the I've read, what made C special is because it's the same for all reference frames. If you're standing still, the speed of a beam of light moving past you (in a vacuum) is C. If you're moving at C - 1 km/h (to someone else) a beam of light moving past you is still C. That's the magic of special relativity in a single image ... Leading to the conclusion that "standing still" and "moving" don't have any inherent meaning; everything is "standing still" relative to itself and only moving relative to other things around it, and the same light (in a vacuum) is always C for all of them at the same time (or slower in another medium like water or glass, but interestingly again always the same velocity in that medium for everybody too IIRC) ... and the way you reconcile that is when Abe looks at Babe moving by at near C, Babe looks like he's shrunk & in slow motion (so to Abe, Babe is moving almost right alongside that beam of light, but he can still predict that Babe himself sees the light is still moving very quickly at C, very far away very fast, because he's shrunk & in slomo).

It's just if you're accelerating vis. your own frame that it gets picky, since then you're speeding up relative to yourself. And when you are accelerating something, time will slow more & more (to a distant observer) the more & more you accelerate it, it gains more and more mass, and you have to pump more and more energy into it to make it accelerate more, with the graph reaching an asymptote right at C where the mass becomes infinite (why only massless particles are supposed to reach it), time stops for the thing, and you can't accelerate it any further. (BTW, wouldn't the thing turn into a blackhole somewhere around the time it reaches near infinite mass? I take it that didn't happen with these neutrinos.)

The (probably bad) *interpretation* I've read about it is that there are fundamental "clicks" of time & space (motion) around the Planck scale (you could imagine it as a spider web; 1 fundamental click of time & space is a thing moving from one node in the web to the next. Even if the web itself has longer & shorter strands & longer & shorter times to move from one node to the next, in relative terms they're all the same "length" and "duration" since all those words mean is moving 1 strand-unit over 1 time-unit). There is no such thing as "absolute time"; there's just the fundamental clicks of clocks, which are always the "same" duration from its own perspective (since all "duration" means is a click of the clock). Each system is its own clock ticking. When A watches B moving by, B's clock ticks have to travel to get to A, so the ticks look like they're slower, but to B of course it's always the same tick-pace (and vice versa). But if B accelerates in his own frame, it's like pushing the next node in the spider web away so one click has to race to catch up to the next node in the web in its own frame; accelerate it a *lot* and it has a long way to catch up to make that click, but B still never notices it since all he measures are still the fundamental clicks, each the same "duration" in relative terms. But in the meantime, A has gone through more clicks in that duration (his web was never stretched), so A is much "older" when the two meet again. Anyway, the aging part has been measured IRL.

Uh, anyway, so C is supposed to be the speed at which one click can never catch up to the next click of time in its own frame if you accelerated to it, because the next node in the web is traveling away faster than an event at the first node can ever catch up to it, so the thing is in ageless suspension until it interacts with something. If you hypothetically sped it up in some "absolute" terms, that is make the first click have to travel even *farther* to catch up to the 2nd click (whatever that means), it wouldn't have any physical meaning you could observe because the second click will still never come, so it'd still be observed as C (I think; I don't know, I'm lost already TBH). So... I think the interpretation was supposed to be something like, since absolute time doesn't really exist, what you're really looking at is the fundamental clicking of a clock, then any speed above when a thing's internal clock stops ticking doesn't matter; it all looks like C to observation, a non-clicking clock. So "faster than C" literally means (under this interpretation), to be observable, you have to observe some click of time, the clock has to be ticking backwards (or whatever you call it), you accelerated the thing to the point where one click never can reach the next click, then you pushed it further so it "arrived" at the second click (that second node in the web) without having the first click ever able to reach it, then later the 1st click of time reaches it. Or something like that. Whatever is going on behind-the-scenes (if there is any) it looks observably like it's clicking backwards in time if you kept up that pace, because the early parts of time arrive after the later parts in time have occurred, and still earlier & earlier parts arrive later and later. I mean, if it had an actual clock on it, it would literally look like the clock hands were moving backwards (to us, what would the clock see?). That's what makes it seem so weird, and why it looks causality breaking, since the effect happens ostensibly before the cause reaches it, or it can somehow reach through time & space to know the cause in advance?

Again, all duration means is clicks of a fundamental clock, each click always having the same duration. Less than <C=normal clicking. C=stops clicking. >C="backwards" clicking (?). Unless the theory just breaks down somewhere, and there isn't really that asymptote at C, or something else weird going on. Whatever it is, it'd be interesting.

I have no idea what I'm talking about, though. I made all of that up sorry.

Painman on 23/9/2011 at 06:02

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A lot of the science behind all of this blows my feeble mind, but I've never really thought that the speed of light was necessarily an absolute limit.

We've had to remodel our understanding of things, based upon new evidence, countless times.

heywood on 23/9/2011 at 07:46

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That comes from relativity which is a consequence of a very simple and fundamental assumption - that the laws of physics are the same for any observer in any inertial reference frame. The number of brain-cramping conclusions you can reach from just that simple starting point is amazing.

Another consequence is the relativity of simultaneity, which means the time order of two events separated in space depends on the observer's reference frame.

With that, it can be shown that the ability to transmit information faster than light is synonymous with the ability to transmit information back in time and violate causality.

If you have a very basic understanding of special relativity and can follow a (http://en.wikipedia.org/wiki/Minkowski_diagram) Minkowski (space-time) diagram, then check out this link. It will explain why:

(http://www.theculture.org/rich/sharpblue/archives/000089.html) http://www.theculture.org/rich/sharpblue/archives/000089.html



If we can reproduce this result and confirm the ability to send neutrinos from one point to another faster than light, then we'll have to remodel our understanding in the biggest way since QM. I think it would mean that either the laws of physics are not the same for all observers, or the principle of cause & effect is wrong.

Harvester on 23/9/2011 at 23:30

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Okay, I get how if you can travel faster than light you can see stuff from the past (if you have a really good telescope, right?). But now I also read about people saying that you can send information to the past, and I don't quite get that. Can anyone explain?

EDIT: never mind, I saw heywood's link and don't understand it so I guess it's beyond my understanding as long as I'm not willing to read any books on special relativity (which I'm not).