posted
I was listening to a radio science program. Two professors debated the idea of the constancy of the speed of light. I am aware of research (begun in th 1970s) that indicates that the speed of light is slowing down. Those studies seem to indicate that light was once 10-to-the-10th-power faster than it is today.
If a story were set in a universe where this is true, what sciences/technologies would be substantially effected?
In particular, if the speed of light fluctuates, what implications does it have on the theories of near lightspeed or faster than light travel and its feasibility?
Edit: I am not really after a straw-poll on who agrees or disagrees with the theory but rather what ramifications you can see if it were correct. I know there was an FTL thread, but I want to discuss the specific idea that 'speed of light is not constant' and all the attendant changes in how we might see the universe if it were true.
[This message has been edited by hoptoad (edited January 23, 2006).]
posted
First of all, everything I've heard suggests that the speed of light is NOT changing.
That said, I think the biggest difference in a world where c is much greater than its present value would be the magnetic field, which is a relativistic effect due to moving charges. I would think--and this is completely off-the-cuff--that magnetic fields would be much weaker. The magnitude of a magnetic field is the magnitude of the electric field over the speed of light. (In SI units.)
Depending on the advancement of the society, this could have large or small consequences. As I understand it, most modern recording technology requires magnetic alignment. And chances are, general relativity wouldn't be thought up until much later (Einstein tackled it by studying EM). Heck, if the magnetic force is weak enough, compasses wouldn't work. That could hinder primitive societies from getting around.
Any of these aspects could make for great writing fodder. What, in particular, are you looking to write about?
posted
Out of curiousity, does anyone know what the effect on earth would be if we didn't have our magnetosphere?
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posted
I'm not a Physicist, but it seems if E=mc**2 and c is decreasing, then there would be less energy in the universe. If c were decreasing at a slow but steady rate, this would be disastrous. (As a side effect, would there be less powerful atomic bombs?)
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posted
If Earth lacked a magnetosphere, we'd get more radiation. I don't think it would be enough to kill us, unless there was a solar flare?
If c were to change... well, if it got a lot slower, and you threw a punch, your arm would get shorter while it was in motion, and time for it would slow down. It would take more effort for it to accelerate.
THere might also be weird effects on molecules (not sure), possibly making atoms unstable, or molecular bonds, or something.
I suspect c was different in the very early universe (the first few seconds).
quote:I'm not a Physicist, but it seems if E=mc**2 and c is decreasing, then there would be less energy in the universe. If c were decreasing at a slow but steady rate, this would be disastrous. (As a side effect, would there be less powerful atomic bombs?)
I don't think general relativity accounts for the possibility that the speed of light changes. I'd guess that if it is changing, then E=mc^2 is insufficient to describe the relationship between energy and mass, or conservation of energy is wrong. Which I sincerely doubt.
posted
The biggest change aside from the magnetic one menitoned is perhaps a biological one.
Not directly biological but one that uses C as means to determine the amount NRG transmitted to a give point in space. (But granted i don't have a specific theory in mind but it might be something like C=NRG/m2 or some other some such hullabulla) But i am not a physicist so as Ebert says my thoeries are for the literay inclined not the mathematical.
So on with it....
If the speed of light was once faster that would to the best of my understanding lead to a greater amount of light "engery" reaching say the outer planets of our solor system.
Take for instance the classic question did "Mars once have life?" If you take the theory that light is slowing down then it is logical to then make the conclusion that the time it takes light to reach earth (489 seconds) could have once been the same for mars which now sits at 11 to 14 minutes depending on orbit.
To take this further perhaps the demise of Mars as a hospitable planet began when sun NRG slowed down to an inhabitable level. Then combine that with say an E.L.E. and bam Martian life ends.
Or from earths point of view. Say we once got light as quickly as Venus/Mercury. As light slowed down over the course of time, our planet began to cool which allowed life to develop.
Again assuming that light was once much faster than it is today. Wouldn't that make Light-Speed travel that much faster? Now take out to the point where a space-faring culture has reached what we can call "relativistic" speeds. Now combine this with a much faster Speed of light and suddenly Interstellar empires are no longer a temporal impossiblity. instead of 20 years at speed of light to get to the next star it takes 2 years or say 2 months, weeks, days or even hours.
This would revoluntize the way we could approach colonization of other systems. Not mention it would help to keep the cultural drift down to a somewhat minimum.
so if the speed of light is slowing, then the amount of energy and mass would have to adjust to compensate. Forgive me but it is too late in the evening to ponder the significance of that change. But, I don't think either mass or engergy would dwindle away to nothing. Also if the speed of light is changing there should be a reason why. How fast a particle of light travels in a vacume would indicat a certain amount of energy pushing it. So if the speed is slowing, I would think that the amount of energy moving it has weekend, and overall, I would guess that it's mass would be increasing. So the light particles are getting bigger?
posted
My first thought is that maybe c isn't decreasing. If the universe were a sea filled with water and you happen to be passing through a denser liquid somehow, then c would appear to be decreasing. Space may be filled with some field/material we can't yet detect. Ether, again.
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posted
I don't know that this would be readily distinguishable from the effects of space-time expanding.
The problems with relativistic and FTL travel aren't because the speed of light is so fast, they're because nothing can go faster than the speed of light. So I can't imagine how a change in the speed of light would have any effect in those areas.
Also, if the speed of light has been decreasing all along, we would have already seen any profound implications for things like the relative effects of the different forces.
posted
Its not that nothing can go faster than light its that nothing can be percievable if it goes faster than light.
In a universe where the speed of light is faster, more of the universe would be percievable. Things that are hidden from sight now because they exist wholely of particles and energy travelling faster than light travels now, would be visible.
posted
Sounds like you were hearing about the idea that the speed of light might have been faster in the very early universe--about the first 10^-43 seconds according to this. So it would not have much effect on the normal universe.
If light was significantly faster than it is now for much longer than that, there would be several problems. The strength of electricity and magnetism are tied to it, according to Maxwell's equations. Increase light speed, and the strength of either electricity or magnetism, or both, have to increase, too. This affects the attractive power of atomic nuclei to their electrons, changing the size of the atomic orbits. Also, there would be an effect on surface tension of water, which would have a major effect on biological life.
Okay, the question I have is that if light could once travel so fast, why can't it again or still? Is it possible to accelerate light... well of course it is it happened at the beginning -- according to some. So if light can be accelerated how (and why) would it be done again. I'm thinking in terms tiny 'packets' of 'faster than light light' for data transmission etc.
I'm not debating whether this idea is good science or not, or whether anyone believes it is accurate or not, but I am wondering what would happen if it were true. Whether we are talking about the 'speed of light' being simply a constant, minimum 'threshold' and if so, what might its maximum speed be.
AndrewR, as to those links, yes it was the work of Joao Magueijo, that prompted the discussion. Maybe this is too vexatious a subject.
[This message has been edited by hoptoad (edited January 24, 2006).]
posted
The universe was smaller back then. Space-time...well, denser works as well as anything, but you shouldn't confuse this with the simple fact that there was more mass-energy per cubic whatsit.
Like Andrew said, if the decay in the speed of light were going to have any effects that we could notice outside of pure theory, we'd have seen them by now. That doesn't mean that it isn't possible that various basic constants aren't all changing in some kind of balanced way, it just means that we wouldn't be able to notice.
quote:Its not that nothing can go faster than light its that nothing can be percievable if it goes faster than light.
In a universe where the speed of light is faster, more of the universe would be percievable. Things that are hidden from sight now because they exist wholely of particles and energy travelling faster than light travels now, would be visible.
I feel the following is my civic duty: nonononononononononononono. Ehem, now that I have that out of my system, I'd like to give a semi-parallel example of your argument. Can you hear things that go faster than the speed of sound? Of course. Why wouldn't you be able to see things going faster than the speed of light? (Well, maybe you couldn't see it with your eyeball, but that's biology, not physics.) The fact is, if Einstein's on the right track, nothing CAN go faster than light. If something did, boy would we be in for trouble. For example, one consequence would be that the less energy something had, the MORE momentum it would gain!
quote:Using a bit of simple algebra,
C = square root of E/m
so if the speed of light is slowing, then the amount of energy and mass would have to adjust to compensate. Forgive me but it is too late in the evening to ponder the significance of that change. But, I don't think either mass or engergy would dwindle away to nothing. Also if the speed of light is changing there should be a reason why. How fast a particle of light travels in a vacume would indicat a certain amount of energy pushing it. So if the speed is slowing, I would think that the amount of energy moving it has weekend, and overall, I would guess that it's mass would be increasing. So the light particles are getting bigger?
First off, something most people aren't aware of: E=mc^2 isn't the full equation. It's E^2 = (mc^2)^2 + (pc)^2 where p is momentum. Photons can have momentum, but they are massless, so in their case: E = pc. Second off, Einstein's equation relies on the fact that c is constant. The equation is meaningless, or at least, only an approximation, if c is variable.
posted
This is slightly off topic, but related. Einstein talked about a person riding on a light wave while gazing into a hand held mirror. Since he would be travelling at the speed of light, the light reflection from the mirror would never reach his eye and he would appear (or actually become) invisible.
My question is related to a story I have completed but there is a problem with "realism." My MC is "riding" a sound wave, but I don't know how to depict this without it sounding cartoon-ish. How would one describe a character riding a wave (either sound or light?) Would sound disappear to the person riding the wave as light disappeared in Einstein's example?
With someone approaching the speed of light with a mirror in hand, everything would appear normal to that person. If they measured the speed of light reflecting off the mirror, they would get C. An outside observer (let's say on Earth) measures the light reflecting off the mirror, they would get C.
However, the Earth observe would notice that the travler's clock ran slower than thiers and thier length (in the direction of thier motion) was greatly contracted. Also the travler's mass would also increase as they approached C.
If a travler did the impossible and reached C (something that would take infinite energy and time), then they would have infinite mass, they would not age, and they would have no length.
Really, C is the speed that all particles without rest mass ALWAYS travel at. Though light might appear to slow in a medium such as water, if viewed from a particle point of view, the photons themselves always travel C.
Wouldn't the speed of light reflecting off the mirror be travelling at the same speed, but in the opposite direction? No matter what that speed is, would the speed of the forward travel cancel out the speed of the backward travelling light and therefore cancel out the reflection to make the person appear "invisible?"
quote:Wouldn't the speed of light reflecting off the mirror be travelling at the same speed, but in the opposite direction? No matter what that speed is, would the speed of the forward travel cancel out the speed of the backward travelling light and therefore cancel out the reflection to make the person appear "invisible?"
First off, I should say that I haven't read where Einstein discusses what it would be like to travel on a light wave, but I'd like to take a stab at your question. I'm picturing the person riding backwards on the wave (pointing towards the wave's backside). When the light hits the mirror and reflects, it stands still at the surface of the mirror because it's traveling at the same speed as the mirror and the passenger. This is the same thing that happens at an event horizon (in fact, it's the only thing of any note). Light pointing radially away from the singularity will stand still.
One thing I should point out is that it wasn't until decades after general relativity was published that physicists actually figured out what things moving at relativistic speeds would really look like to observers. Most people still think, in fact, that if a person moving close to light speed passed you, you'd see that person squished in the direction of travel. This is not the case! After consulting Google, here's a link that can explain much better than I: http://faraday.physics.utoronto.ca/PVB/Harrison/SpecRel/Flash/ContractInvisible.html . So, even if it was Einstein who gave the riding a light wave example--and it may be perfectly valid--take it with a grain a salt.
quote:Umm...just to refer the "is it real and/or true" posters the OP wanted the ramifications of scuh as if it were true.
Maybe I'm just misreading the posts
First of all, I'd like to apologize for the possible curtness of my previous post. It wasn't meant that way. I blame multiple conversations while trying to type. Never a good combination. Second of all, the possible ramifications are a direct result of how light speed changing is possible. The current theory of gravity that puts lightspeed on its pedistal only works if light speed is constant. To ask what it would mean if it's not constant is to ask what is missing from that theory. This is a question which the theory itself cannot address, clearly. However, unless hoptoad is expecting an abstract in theoretical physics, the best he can hope for is what would happen given our current equations combined with different values of c. When giving this conjecture, responsible students of science should provide caveats that their answers rely heavily on how they answer the question "is it real and/or true?"
posted
Do dark matter and dark energy act the same as "regular" matter and energy with regard to Einstein's equation?
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posted
Dark matter and dark energy are a giant question mark-- scientists believe it makes up most of the universe, but don't know what it is. Dark energy, it is thought, is the force that is causing the universe to expand faster and faster.
If dark matter is just a host of particles that do not interact with normal matter except through gravitation, then it could be expected to obey all the same rules.
Maybe I'm going out on a limb, but I believe if it were possible for a particle to have negitive rest mass, then they would ALWAYS travel faster then light, and would ALWAYS travel backwards in time, not forwards. They would be tachyons. It would be impossible for such a particle to travel under the speed of light.
[This message has been edited by ChrisOwens (edited January 25, 2006).]
posted
-------------------------------------------------------------------------------------------------------------------------------------------------- Wouldn't the speed of light reflecting off the mirror be travelling at the same speed, but in the opposite direction? ------------------------------------------------------------------------------------------------------------------------------------------------- The observer going at the speed of light, thier clock would stop ticking as it were. An infinity of time could pass by, and they not observe anything, for they would be frozen in time.
More realistic is the idea of an observer coming within a fraction of the speed of light. The speed of forward travel would never cancel the speed of backward traveling light, for them the speed of light is C, to an outside observe the speed of light is C.
It's the second postulate of special relavity, the speed of light is invariant, absolute, irrespective of the motion of all observers. Space and time are relative, and bend over backwards as it were, to the constant speed of light.
[This message has been edited by ChrisOwens (edited January 25, 2006).]
posted
No, when you square a negative quantity...you see where this is going. Tachyons need to have imaginary mass. Which is part of the reason pragmatic thinkers have trouble believing they exist Posts: 8322 | Registered: Aug 1999
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posted
Thanks for what has proved a spirited discussion. I wasn't asking for anything hard and fast but it is interesting to consider the pivots upon which our understanding of the UNIVERSE are balanced. The stupid idea (and when I consider some of the people responding to this thread, I realise how silly my ideas can appear) is this: something elastic expanding to its maximum, that point where it is about to contract, appears static--or constant. I was just wondering what would happen if we just happened to be at that point in the history of the universe and whether it would even matter if things began to contract.
As I said, not the most scientifically well-informed idea. but it was my thought. (I'm embarrassed now.)
[This message has been edited by hoptoad (edited January 27, 2006).]
posted
It's not a silly idea at all. However, in terms of the speed of light, we've been at that static point for at least a very long time, now. That "7% in the last two hundred years" is pure hogwash.
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posted
I don't think it's silly for SF to ask, "WHAT IF the speed of light changed over time?" That's the whole purpose of speculative fiction, to ponder the impossible.
I read an interesting SF book 3 years ago, where the science was based on the Aristotelian ideas of ancient Greece. There the planets and the sun revolved around the Earth, each planet was fixed in a sort of transparent sphere. Obviously, none of it is based on modern day understanding, but it basically ask, "WHAT IF the universe was Aristotelian?"
The challenge, greater than fashioning a credible and self-consistent milieu, is crafting an intriguing tale that we care about. Otherwise it will be, "So what?"
quote:I'm not a Physicist, but it seems if E=mc**2 and c is decreasing, then there would be less energy in the universe
This is called entropy.
quote:Out of curiousity, does anyone know what the effect on earth would be if we didn't have our magnetosphere
Aside from poor radio reception, a lot of dead animals.
quote:7% in the last two hundred years
Preposterous.
If C is changing, it is not a variable, but a decaying constant. It is effectively constant at any given epoch. If c is slower, then all the relativistic effects compress and we start seeing them at slower speeds. It's perhaps a side effect of entropy. Because energy is wasting away, c could be slowing, and perhaps energy is wasting away because the universe is expanding, and by triangulation then, c is decreasing because the universe is expanding. But this is all conjecture and probably doesn't have enough backing to keep any story set in such a universe from being science fantasy.
posted
I am honstely not trying to flame, or start a flame. This is my opinion, and belief, and by no means intended as an insult to anyone here.
"According to the researchers they can detect a 7% shift in the last 200 years." Did they go back in time 200 years and perform the EXACT same test with the EXACT same equipment? Or did they do the test twice, come up with results that were nearly infinitesimal and say, "My God, Jim! The speed of light constant has decreased! At this rate, the speed of light would have been seven percent faster, two hundred years ago than it is today. We had better document this as a fact, because we are scientists and we know."
They do this all the time! They take theories and assumptions and call them FACT! And anyone who doesn't believe these so called "facts" are not "educated" and are therby STUPID!
... <sigh> ...
If they found a discrepency between several tests, there are so many things that could have affected the results. Perhaps the test equipment was affected by some micro-magnetic fluxuation in earth's field. Perhaps the speed of light itself was slowed down due to some kind of solar, or terrestrial magnetic, or gravitational fluctuation.
Im sorry everyone if I offend. I don't mean to offend any of you. I am just frustrated with the obtuse attitudes shown by the science industry these days, who seemingly consider every theory they come up with as cold hard fact. Maybe their theory is correct, but maybe not. Thats why it's a THEORY. This is unrelated to the speed of light, but consider this for a moment: If the Colorado River carved the Grand Canyon over the course of "millions of years", why is it that the land elevation (not the river, the land the river runs through) is HIGHER in the middle, than where the river starts? I have a theory about that... ask me sometime about it if you like.
Back to the speed of light. Okay, if it's slowing down, I agree with the theory that it would probably change molecular orbits, and gravitational strength of mass. I also believe that it would be imperceptable to us as everything around us would slow down in the same way. From a literary point of view, you could easily get away with saying that is IS perceptable, and make up something that seems like a reasonable effect of this phenomenon. I don't read Sci-Fi stories to learn "scientific fact". I read them because they are entertaining, and escaping.
posted
deRost, you weren't offensive. I agree that too often things are labeled as "fact" when they are only just a theory. Helicopters are around because someone educated told the creator it would never fly. Hmm...had to change a law of physics for that one. The poor bumblebee was another little speedbump on the laws of physics.
If you look at the medical world, what's good for you today and what's good for you tomorrow is most likely going to change.
I think the world of science would move faster if the die hards were more open to a possibility that not everything is set in stone and can't be changed. For some reason that doesn't happen near enough. NASA has been setting people on a controlled explosion for years to get them into space. And for the last...50 years?...what new methods have the come up with? A reusable shuttle, which hasn't seen a real improvement since the first one was built.
I try and keep up with some of the new advances in science, but not being a physicist I stick to the idea over the details. But stopping light has happened, and it can store data in a suspended state as well.
posted
It depends on the wave/particle paradigm, light as a wave slows in a medium, but-- photons always travel at C, never above, never below.
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posted
Well, I would assume that if the Grand Canyon (which is pretty grand, for Earth) could be carved by erosive forces, similar erosive forces could be carving the surrounding land a bit too. There's also tectonic forces that raise and lower land elevations over time, sometimes too slowly to prevent a river from carving it's existing channel a bit deeper rather than allowing itself to be diverted.
I think that the idea of a massive superquake or giant kinetic bolide ripping Colorado a new one (back before it was called Colorado, of course) is a fun idea, but I don't see the evidence to support any such theory. Not that anyone's really tried to prove whether or not something like that could have happened, so I guess I'll have to leave the matter open.
I don't see what that has to do with something like a change in the speed of light. The question of what happened to cause a certain geological formation on the face of a rather ordinary rocky planet is not terribly significant compared to the question of whether one of the fundamental characteristics of the universe is changing measurably over the course of a couple of centuries.
Although, when you get right down to it, I don't see any important changes other than that the universe would effectively be getting larger at a much faster rate than seems plausible. That's all I'm saying. Speed of light gets slower, universe gets bigger.
Or, perhaps you could think of it as everything else shrinking. Same difference.
posted
Yes, my comment about the Grand Canyon was a bit confusing. I mentioned it mostly as an example of how scientists seem to attribute things to one theory and claim is as fact. Even though there are much more plausible theories about the subject. It can apply to many topics, but this is the first one that came to mind for me. I'm just a tad passionate about my misgivings.
Anyways, I think the idea of light slowing down could be a very interesting aspect to a Sci-Fi story, and your explanations definitely do not need to be accurate. Just plausible, and believable.
quote:I am just frustrated with the obtuse attitudes shown by the science industry these days, who seemingly consider every theory they come up with as cold hard fact. Maybe their theory is correct, but maybe not. Thats why it's a THEORY.
You're getting theory and hypothesis mixed up here.
The media very often reports hypotheses as "theories." But a hypothesis has only a few, or one, study that supports it. It is a tentative idea.
A theory, on the other hand, has a great deal of data supporting it. It usually has passed many chances of being falsified, and has been challenged repeatedly by experts in the field. It is, as I understand it, one of the strongest terms in science for an idea.
(Remember, scientists are an ornery bunch. Many of them love nothing better than to show they are smarter than the next guy, if only by shooting down the other guy's hypothesis. So any hypothesis that has withstood the test of time has been run through the ringer several times by guys trying to make a name for themselves. It means it is a pretty good idea based on the facts that we know.)
"Just a theory" is like saying "just a law." There is that much confidence in a scientific theory--IF the term is used correctly.
posted
Um...no, that isn't exactly how it works in practice. Look this thread doesn't exist to debate the merits of the scientific community as it now exists. We should probably drop the subject.
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