Hard Light Productions Forums
Off-Topic Discussion => General Discussion => Topic started by: Bobboau on September 11, 2011, 12:56:07 am
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I just considered something, as an object approaches the speed of light it's mass increases to infinite, strong moving masses cause frame dragging, objects in a dragged frame can appear to move faster than the speed of light (particles within the ergosphere of a black hole), wouldn't this mean that as a ships approached the speed of light it would drag spacetime with it and thus be able to appear to move faster than the speed of light?
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Big problems are 1) getting that fast takes a huge amout of energy, because the object is gaining mass, which takes more energy, etc. and 2) all inertial reference frames must be equally valid or relativity gets thrown out the window, and we can't have that.
Also, I'm not certain that causing a dragged frame and being in a dragged frame are necessarily the same thing.
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what type of mass does an object gain ?
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I think this may be a confusion of rest mass vs. relativistic "apparent" mass. The latter doesn't actually cause an increase in gravitational field from the frame of the object (I think?). From an external frame, I wouldn't know.
edit -- I'm really drunk, not really trying to think this through right now. inb4 herra
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Nah, it will appear a certain way based on this. (http://en.wikipedia.org/wiki/Lorentz_transformation)
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I wouldn't imagine a space ship would be gaining mass when activating the FTL. Why would it gain mass when space is moving around it?
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because that is how relativity works. time moves slower, distance gets shorter in the direction of motion and mass goes up.
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Relative to an observer in a different inertial frame of reference.
Relativistic mass follows the expression m=γmo, where gamma is 1 over the square root of (1-v2/c2).
The key term here is v, which is the relative velocity between the object and the observer. An observer on a fast-moving spaceship sees no such increase in mass.
So I'm mostly sure that there isn't actually any increase in gravitational field strength for an object accelerated to high velocities. Also my understanding is that it's not even the mass that should be discussed in this aspect of relativity, but rather the momentum. Apparently a number of physicists seem to prefer to avoid the concept of relativistic mass altogether. Unfortunately I'm not well versed enough on this subject to be comfortable going much further into it.
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yes, well the hypothetical space ship would be moving relative to the two end points of it's journey, and what we are interested in is what everything looks like from the three perspectives. if mass increases as velocity increases, then shouldn't the reference frame appear to drag space along with it more? and then shouldn't the apparent speed of light go up in that region? I don't know, it seems sort of like a contradiction. I posted it here because I know there are a few people who know their physics and would be able to tell me why not.
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In truth, I don't know my Relativistic Physics so my understand that space is a fabric and it can be warped. My in-depth understand of how the FTL works is very little. I understand subspace from Freespace that is about it. ;p
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and then shouldn't the apparent speed of light go up in that region?
This particular comment motivated me to write something on this thread. The interesting result of the nature related research is that no matter the state of movement of the observer or the source, when measuring the speed of light, one will always find it to be c. This is confirmed by multitude of experiments, and no-one has ever been able to detect any difference. Note that I have to add that this is according to current understanding, this addition is meant for those people who might happen to read this 500 years later in the future and laugh about the stupid beliefs of 2000s and so that I don't look completely silly. Seriously though, particles going faster than c have been sought in multitude of experiments, but no-one has ever been able to find one. If you can, Nobel prize is awaiting for you!
"Speed of light is a constant." What this means is surprisingly hard to understand, since it contradicts common sense.
To screw your minds more, when photon starts from the vicinity of a large mass and travels towards space, it undergoes a red-shift, i.e. it loses energy. When it goes towards a large mass, it experiences blue-shift, and thus gains energy. Even though speed of light remains at c, its energy content doesn't! Makes you kind of feel that at least something is conserved, doesn't it? The way I explain this to myself is that either time unit or distance metric (which are basically the same thing) screws us since they don't behave in a linear sense close to the relativistic speeds or large masses.
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ok, the thing that got me thinking about this was this (http://en.wikipedia.org/wiki/Ergosphere), if the space is moving at the speed of light, such that if you moved against at the speed of light it you would appear to remain constant, then what would happen if you moved with it?
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Well, if you are constant with light then it would appear that you are not moving right? I think I'll go with Frank Herbert's Folding Space for now.
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dune never really attempted to explain how their ftl worked as far as i can remember (maybe there was something in heretics/chapterhouse, but its been years since ive read those). it did require that the navigators had some degree of prescience for reliable navigation, hince why spice was so important for space travel. if you accept the brian herbert/kja books as cannon (i do not), space travel was not impossible before the holtzman engines were invented, but this form travel took months. they really did not explain it in depth but for that kinda travel in that amount of time i think you would still need a form of ftl. i think dune just assumes einsteins theories were wrong, or at least did not accurately model relativistic travel.
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@bobboau
Heh, well moving against the motion of the ergosphere completely (ie, maintaining a fixed radial position relative to the center of the black hole) is impossible, because that requires moving at the speed of light. ;)
In practice though I don't think the situation would be any fundamentally different than considering your maintaining a fixed position exactly on the event horizon -- in both cases you're precisely countering the "motion of space". In both cases you appear infinitely red-shifted and time-dilated for an external observer, because the photons lose all energy trying to escape the horizon.
Edit: Though I stress that for the example of the ergosphere, that's for the observer being behind your current direction of motion. The ergosphere rotates around the hole, so photons leaving you on different vectors (eg, tangentially outward to your path of motion, or forward along with it) certainly do escape with energy to spare. This means that parts of your path around the hole are visible, with varying degrees of red or blue-shift and time dilation. You'd appear slowed down and red-shifted while moving away, sped up and blue-shifted while moving towards.
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I think that folding space in "Dune" is just that, some device used to compress ("fold") space between two points and travel through it as sub-light speeds. Energy requirements are atrocious, but it doesn't contradict laws of physics (according to one theory, at least). While matter nor energy cannot exceed speed of light, space can (and does so when expanding).
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sped up and blue-shifted while moving towards.
this is that part that interests me, how sped up?
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So, I have a question:
A laser fired in the direction of travel from a spacecraft travelling at 0.25c, would an outside observer be able to measure the light travelling at 1.25c or would it end up being 1.00c??
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1.00c
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Indeed, 1c, regardless of the velocity of the observer. The speed of light in vacuum is constant and independent of the frame of reference of the observer or the motion of the source.
jr2: Your example is based on a principle that sounds really weird and contrary to common sense, yet is demonstrably true. Velocities are not linearly additive, which means you can't simply add the numbers together as you'd expect. If I'm driving down the road at 60mph, and I throw a baseball out the window at 40mph (relative to me in the car), and I throw the ball in the same direction that I'm driving, then you'd expect to be able to say that the speed of the baseball relative to the ground is 60mph + 40mph = 100mph. But this would be wrong! It's actually 100mph minus a tiny little bit, that little bit is because of relativity.
If you examine the math behind this, the effect ends up being insignificant at small, every-day speeds that we're used to, but very significant at speeds close to that of light.
Bob: I'm really not sure how to answer that exactly -- it would depend on your speed and trajectory around the black hole, the black hole's mass and angular momentum, as well as the position of the observer. It's mathematically too involved for me to be willing to try to go through, sorry. :P
I suppose what I can do is recommend looking at this website (http://jila.colorado.edu/~ajsh/insidebh/index.html) that Astronomiya provided for me a while back during a similar discussion on black holes and relativistic effects. It's a really nice one and might help provide further insight. :)
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That is why Mr. Einstein came up with the idea of wormholes. They exist in equations, but not in real life. You need Negative Matter to open one up and the energy for that would be massive! It would be best to siphon a star's energy to do that.
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I've just had a thought - yay me
I must be traveling at the speed of light relative to something in fact (or maybe not :D) isnt everything
also if i shine a laser, imagine the first 2 photons emitted are they not moving relative to each other
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Indeed, 1c, regardless of the velocity of the observer. The speed of light in vacuum is constant and independent of the frame of reference of the observer or the motion of the source.
jr2: Your example is based on a principle that sounds really weird and contrary to common sense, yet is demonstrably true. Velocities are not linearly additive, which means you can't simply add the numbers together as you'd expect. If I'm driving down the road at 60mph, and I throw a baseball out the window at 40mph (relative to me in the car), and I throw the ball in the same direction that I'm driving, then you'd expect to be able to say that the speed of the baseball relative to the ground is 60mph + 40mph = 100mph. But this would be wrong! It's actually 100mph minus a tiny little bit, that little bit is because of relativity.
If you examine the math behind this, the effect ends up being insignificant at small, every-day speeds that we're used to, but very significant at speeds close to that of light.
If somebody bothered me enough, I could brush up some relativity stuff from University times from my bookshelf dust bin and look if the relativistic observers will also agree on the frequency of the emitted light. My gut feeling is that they will not, but I cannot say this for sure. But nah, let's not go there yet, somebody has to ask first. Nicely.
EDIT: ...aaaaand by a brief look in Wikipedia brushed up my memory enough that this indeed happens, and got the nagging feeling that it should have been self-evident.
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I've just had a thought - yay me
I must be traveling at the speed of light relative to something in fact (or maybe not :D) isnt everything
also if i shine a laser, imagine the first 2 photons emitted are they not moving relative to each other
Well, everything is always moving at the speed of light in space time. That's why moving super fast or a lot actually allows you to live "longer", since you've used some of your velocity to move spatially and reduce the amount you move temporally. As for whether you are moving at the speed of light spatially relative to some other massive body? No. Not possible.
@ the laser question: A photon doesn't experience time. It is everywhere in its trajectory at once from its point of view (another way to think of it is that it's moving so fast that length contraction shortens the universe relative to the photon into a 2D plane, which is orthogonal to its velocity), so you can't really say that a photon looks at another photon and sees it moving at 0, since nothing moves relative to a photon.
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Today we have learned that relativity is mind bending just as much as it is...
space-time bending
YEEEAAAHHH :cool:
edit: okay that was terrible, i admit
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I will admit I can understand astronomy, but FTL just makes my brain melt. So, does anybody what to learn the lifecycle of a Supergiant?
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Wait till you study a Bistromathic drive
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Bistromathic Drive, eh? Sounds interesting, be sure to post pics, they help, a lot!
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Unfortunately a Bistromathic drive is usually encased in a sep field (Somebody Else's Problem Field)
"A SEP is something we can't see, or don't see, or our brain doesn't let us see, because we think that it's somebody else's problem.... The brain just edits it out, it's like a blind spot. If you look at it directly you won't see it unless you know precisely what it is. Your only hope is to catch it by surprise out of the corner of your eye.
The technology involved in making something properly invisible is so mind-bogglingly complex that 999,999,999 times out of a billion it's simpler just to take the thing away and do without it....... The "Somebody Else's Problem field" is much simpler, more effective, and "can be run for over a hundred years on a single torch battery."
This is because it relies on people's natural predisposition not to see anything they don't want to, weren't expecting, or can't explain.
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So, I have a question:
A laser fired in the direction of travel from a spacecraft travelling at 0.25c, would an outside observer be able to measure the light travelling at 1.25c or would it end up being 1.00c??
OK, I got an answer on this, which was 1.00c
So, next question... will there be a sort of Doppler Effect for the light? I mean, the light is being fired from a vessel travelling at 0.25c, and the light is travelling at 1.00c ... would the light accumulate or become more... dense, as it were or maybe intense is a better word, in front of the craft?
If you don't understand what I mean, think of a garden hose firing water. Now imagine the garden hose moving forward, but only at 0.25x the speed that the water is being fired at.
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That would result in the light sent out being blueshifted for an observer in the ships' flight path.
Conversely, if a ship travelling at fractions of c was travelling away from you, it's emissions would be redshifted from your perspective.
Yes, this is an application of the Doppler effect.
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Interesting. So, this blueshifting will occur?
Yes/No
And
will appear blueshifted to:
a) source
b) target
c) observer from sidelines
OR some combo of a, b, and/or c?
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For the source, and an observer on the sideline, the laser will not appear blueshifted.
For the target, yes, blueshifting will be visible.
Addendum: For the source, any emission source in its flight path will appear blueshifted, while every emission source behind it will be redshifted.
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:cool: Interesting. Would be rather cool to have some sort of mod where the FTL isn't subspace based, maybe not even real FTL, just like 0.95c.... have subspace walls basically be a filter for the starfield, and blue / redshift them, depending on what stars are in front / behind the direction of travel. Maybe make it an escort mission.
SO,
Idea for a mod:
You are travelling at 0.95c, and you must do escort duty for a top-secret diplomatic envoy from Earth, as hostile aliens have subspace FTL tech and can jump in out of the blue. (haha, no pun intended) You are equipped with the latest experimental weaponry that still needs to be fine-tuned and have the bugs shaken out of them. You might have shields that are of the same type, not really reliable, but the tech improves as your techs work the bugs out. You are travelling to reach another FTL tech capable alien race that is rumored to be benevolent (or at least, has a sense of fairness) and request assistance defending from hostile alien race. However, you must neutralize ALL hostile alien patrol craft that jump in, or else they will contact their superiors and you will be found out. (Of course, since being overrun by hostile alien race, all contact with other races is strictly forbidden.) Sympathizers from the hostile alien race informed members of the government(s) on Earth about the existence of benevolent race(s) (maybe alliance) that you are attempting to contact.
Along the way, maybe you try to capture alien craft to attempt to reverse-engineer their FTL drives (whereas, on Earth, of course, that's verboten and shooting down alien craft would be capital offense, but out here, you might as well). That's another objective, you also have research craft / or research station on main diplomatic craft that will attempt this... maybe make for interesting missions where you attempt to test experimental FTL drives with the risk that something might go wrong.
Aaaand... that's my little thread hijack. ;)
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Presupposes magic drive tech that can accelerate/decelerate from and to near c without requiring a near-infinite amount of energy, and can maneuver at those speeds.
Also presupposes that your little fleet can actually get valuable sensor data while travelling at those speeds; purely light-speed sensors won't work very well when all you see forward of you is blueshifted into insane frequencies.
Also note that your theoretical FTL-capable craft will not be able to catch something travelling at near c, supposing that the FTL works similar to FS (meaning that ships exiting FTL do not conserve momentum from when they entered FTL).
And finally, an observer in the craft's flight path will not have much time to react to detecting it on lightspeed sensors, as the ship will be shortly behind the photons announcing its presence.
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Add to all that relativistic beaming, and it would be very difficult to play, unfortunately, although it is a very cool thought exercise. In our ship traveling at .95c, if you were to look behind you, you would see nothing. If you look forward, you'd see everything around you concentrated in a cone in front of you. Yes, this includes stuff that is actually behind you. What you would actually see is a blueshifted region directly in front of you, and a redshifted annulus around that.
More info, pictures, and movies here (http://jila.colorado.edu/~ajsh/insidebh/4dperspective.html).
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Great. :doubt: I guess it'd have to be rule-of-cool then. ;) But, it is interesting knowing how these things would actually work / appear. :nod: Thanks for the replies!
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http://www.bbc.co.uk/news/science-environment-15017484
DUN DUN DUNNN
neutrinos going too fast for light, it appears.
Well, possibly, they're looking for another reason
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oh sweet
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hopefully they will use this
discovery anomaly to make warp drive, or at least a cool new way to blow ourselves up.
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Le sigh.
Forgive me for being the pessimist of the group, but I don't buy that for a nanosecond. Anything moving FTL necessarily involves breaking the theory of relativity, which is one of the most vastly successful theories in 20th century physics. It's been confirmed so many times it's considered established fact, and indeed the very particle accelerator those researchers are using relies on relativity to work properly.
Here's what bothers me about this news:
"My dream would be that another, independent experiment finds the same thing - then I would be relieved," Dr Ereditato said.
But for now, he explained, "we are not claiming things, we want just to be helped by the community in understanding our crazy result - because it is crazy".
No, if he was genuinely trying to get the scientific community to verify his results, then he would have just posted the findings on arXiv or similar scientific circle before drawing a huge media fuss over it. But as far as I can tell, no such publication of their data/findings yet exists. What they're doing is a classic example of media grandstanding for the sake of attention.
Edit: Also io9 (http://io9.com/5843112/faster-than-light-neutrinos-not-so-fast) has a nice summary of their concerns about it.
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just because relativity was successful and is correct in most cases. doesn't mean that we have a complete picture of how the universe works. this was similar with newtonian physics. it had very practical applications and was responsible for the industrial revolution, yet it had gaping holes in it that were not explained until einstein came around. finding a hole in relativity would actually be a very interesting thing. relativity works quite well, our gps system wouldn't work without it, so if we find a case where it is not doing what its supposed to be doing, it wont invalidate the theory and all its practical applications, but rather open the door for a higher understanding of the universe. that said im not holding my breath. it is likely a glitch in their equipment.
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What Nuke said, basically. Even though we now know that Newtonian mechanics is far from a complete picture of objects in motion, it's still immensely practical for most everyday purposes. In the same way, we may find that special/general relativity breaks down at some point, yet can still be successfully used to predict common phenomena. (Along the same lines, there's a big part of me really hoping that "dark matter" winds up being some crazy new quirk in how gravity works on very large scales, as opposed to just a bunch of massive stuff that we can't see.) These particular results are obviously far from certain, but it's worth keeping an ear on them.
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Well sure, I'd be thrilled to see this finding get verified because it certainly would require a profound reworking of theory, but just like Nuke said I'm not holding my breath.
Let me put it this way. If this result is validated, then we need to explain why our understanding of relativistic kinetic energy is so wrong -- to accelerate a particle of nonzero mass to c requires infinite kinetic energy to be imparted to it. Yet if this was wrong, then we should have had absolutely no trouble accelerating things past c long ago.
Next you'd have to explain why the mathematics of relativity, particularly the Lorentz transformations, are so wrong, because they show that a particle moving at speeds greater than c is functionally the same as a particle moving backward in time from some reference frames -- this violates causality. And yet this mathematics works for everything from cars to satellites to space probes to relativistic particles just like the ones we study at the LHC.
And what is so special about these neutrinos, I have to ask? We've observed neutrinos from supernova SN1987A and their arrival time exactly coincided with what you'd expect from neutrinos produced from the core collapse of the star and radiating outward at exactly the speed of light. What is it that's making these LHC neutrinos go FTL? How did they measure this? What were they doing to cause such a result in the first place? I have no idea, because I can't even find their data. Nevermind, here it is (http://static.arxiv.org/pdf/1109.4897.pdf).
And I'm really not buying the Newtonian vs. Relativity argument either. Newtonian physics wasn't based on experiments involving things moving at near light-speed. Relativity was. That's why Newtonian physics works well for every day speeds while relativity works for everything. As you've both mentioned, it's not so much a replacement, but a modification to describe a bigger picture.
This discovery on the other hand -- I can't see how it'd be a modification like Relativity was for Newton. Rather it would require essentially going back to the drawing board, because as described above, it is completely at odds with what we've already established with relativity. It would be like finding fossils of homo-sapiens in a precambrian formation. That would be one hell of an observation to have to work into your theory.
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^Alternatively, Causality could be thrown out instead.
But I wouldn't like that.
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Actually I'm hoping that's exactly what happens. :warp:
I think I recall reading somewhere that space, at the smallest scales of distance/time, might actually be non-causal in nature... or maybe it's non-locality I'm thinking of. I'd need to look again.
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another option, what if this is negative energy? IIRC no one is quite sure what that would look like.
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Great! Then we can open a wormhole!