Neutrinos: Faster Than Light? (Page 2)
CoIin: On further reflection, I'm starting to get the feeling that the confusion above is a result of the problem of "incommensurability" between theories or paradigms which Geoff, Corvin and myself have broached in other threads.
Mass was a critical element in the ideas of both Newton and Einstein, but apparently they were not talking about the same beast at all. As I understand it, mass, under Newtonian mechanics, is invariant. Under Einsteinian mechanics, however, it is relativistic (i.e. it changes). I think if we examine the scenario above closely, we'll find that Prof Feldman is equivocating between the two different "masses".
Note when Prof Feldman says "Neutrinos have (very small) mass", he seems to imply an absolute, invariant quality. (i.e. he seems to say, it's small and is ALWAYS small, no matter what the neutrino is doing)
Later when he says "its mass increases", he seems to have flipped to relativistic mass.
CoIin: Yes, you too can be as confused as me . This is quite interesting though, not that I understand it all.
(I'd always wondered how, if light is a form of energy, and energy is equivalent to mass, why am I told that a photon has no mass. The answer lies within )
lori100: the past and future do exist in alternate realities, remote viewers have been trained by the govt to learn to access the past and future events , out of body travelers have experienced it also...., everyone will eventually learn it, it is everyone's destiny to fully experience their mult-dimensional existence......I have experienced future events in dreams many times.....
(Edited by lori100)
Yan26: @DawnGurl Could you please post a link of an article claimng that neutrinos travelled faster than light.All the ones I found were related to the Italian experiment.
@Corvin It is possible for the realtive speed of an object to exceed c( speed of light) .
Relativity states that any object travels at the speed c( also speed of light) in the space time continum. This means if your speed through space is 0 your speed thorugh time is c. If your speed through space is c then your speed through time is 0. Which is why you stop aging when you travel at light speed. There is nothing about relative speed between two objects being limited to c.
@Colin E=MC^2 In this equation c is the speed of light through vaccum and is a constant. So if F increases the M has to increase. as M increases the speed becomes slower so you have to put more force which in turn increases M.Which means the Force required to push even a Hydrogen nucleus into light speed would be very high or infinite. Photons are considered massless I believe.
Also Relativity has nothing to do with Dark Matter. Dark matter was used to try and explain why Galaxies are expanding instead of contracting( to make a long story short).
Also it is interesting to note that for an external observer an object can never arrive before it has left. Eg
Suppose a sapce ship starts at 09 Am on 1st January 2013. Travels instantly at the speed of light for a distance of half a light year ahead and then back. When the space ship reaches back for the people on earth the time taken for travel was 1 year as their time has is 09AM 1st January 2014. But for the person on the spaceship the time is still 09AM 1st January 2013. It is only his time which has not changed, Everybody else's has.
Now supposer a sapce ship starts at 09 Am on 1st January 2013. Travels instantly at the speed of 2 times light for a distance of half a light year ahead and then back. When the space ship reaches back for the people on earth the time taken for travel was less than 1 year. However for the man on the spaceship the time would be before 09AM 1st January 2013. Maybe 09Am 1st January 2012. But the point is for the external observer the spaceship has come back after it has left. It is only for the observer on the spaceship that time travel has occured.
Hence it would be impossible to go back into history even if breaking the light barrier was possible. As everyone else around you is moving forward in time.
Corwin: @Yan - A photon does indeed have mass (potential mass). As it travels at the speed of light, it's mass is in the form of energy... but when you stop a photon in it's tracks, this energy is converted into mass. This is why light can "push" on things. (things and stuff)
DawnGurl: @Yan: http://www.nature.com/news/neutrino-experiment-replicates-faster-than-light-finding-1.9393
faster than light neutrinos...or so it claims. I'm beginning to seriously doubt the veracity of this claim.
Corwin: It is very likely that it's merely an error in measurement... but who knows?
If it turns out to be real, we would be led to some very interesting conclusions.
But it still won't get me any closer to my flying car.
DawnGurl: In 1987 a star went super nova and its light reached earth after traveling 80,000 years. Experiments at that time measured when the light from that super nova hit their target as well as the neutrinos. They both arrived at exactly the same time. I just found this out. Sorry Corvin; no time machines today.
DawnGurl: No! Its very useful! Just think of it as the world's most imaginative planter!
Corvin's DeLorean: Pick-a-flower! Just $2.99 each (plus tax)
But the article doesn't mention any actual experiments that confirm this warping of space.
I'm skeptical.... but I hope they are on to something... I'd like to start planning my vacation to Alpha Centauri.
CoIin: Mornin' all . It's amazing what a good night's sleep will do to clear the cobwebs. I think I see part of the reason for my discomrobertulation now. I've been confusing special and general relativity.
Special relativity deals only with frames of reference in uniform motion (i.e. no acceleration). Under such circumstances, the kind of symmetry I was referring to earlier WILL obtain. That is to say, all relativistic effects I observe in you (time dilation, length contraction, increase in mass, etc) will also be observed by you to affect me in precisely the same degree.
My mistake (or one of them ) was to assume that this symmetry also obtains under general relativity where acceleration must be taken into consideration.
Conclusion : I'm pretty sure I'm right about Corvin's lightbulb scenario, but not really sure about anything else
CoIin: @ Yan - "Also Relativity has nothing to do with Dark Matter. Dark matter was used to try and explain why Galaxies are expanding instead of contracting( to make a long story short)."
The findings further support the already well-entrenched general theory of relativity, which has been successful in predicting many cosmic phenomena observed throughout the universe.
Yet there are still competing theories that have been proposed in recent years to accommodate the strange discovery that the universe seems to contain much more mass than simply the visible matter we can see, and that the cosmos seems to be accelerating in its expansion, propelled by an unknown force.
Within the framework of general relativity, scientists have invented concepts called dark
matter and dark energy, respectively, to deal with these problems. But some researchers say these bizarre inventions aren't necessary if we simply tweak general relativity itself.
Yan26: @Colin. Your post says that "Within the framework of general relativity, scientists have invented concepts called dark matter and dark energy, respectively, to deal with these problems." These problems doesnot refer to a problem in relativity. But the problem of excess mass in the universe than what is visible.Dark matter was created to explain what appears to be excess mass in the universe. It wasnt created to prop up Relativity. Yuor earlier comment
" but when we have to posit that 96% of the universe's furniture is the so-called "dark matter" and "dark energy" (how's that for the mother of all ad hoc hypotheses? ) in order to save the theory, things would appear to be getting a bit precarious."
It seemed to me that you were stating that dark matter was introduced to explain a discrepancy in Relativity. Which it wasnt.
CoIin: Well, this is how I understand it....
General relativity is a theory of gravity. The behavior of galaxies is inconsistent with the predictions of GR. So either:-
1. GR is wrong (tentatively)
2. GR is right (tentatively), but there's something we don't know (enter dark matter )
It's analogous to the example of the discovery of Neptune I offered earlier. The only difference is, the ad hoc dark matter hypothesis hasn't been vindicated yet. It may be in time. Or it may never be.
CoIin: Dammit! I must be getting old. I almost forgot the delicious third possibility.
3. The facts are wrong!!!
(see how easy it is to take facts - in this case, the data relevant to the behavior of galaxies - for granted? )
Yan26: @Corvin - Photons do not have a rest mass. In fact a photon cannot be stopped.It is pure energy and always gets completely absorbed. For eg During photoelectric effect a photon gets completely absorbed. The below is an interesting link in that.
@Colin: When astronomers studied the movement of Galaxies they found it to be at variance with the theoritical calculations. Thus one of the theories suggested to explain this anaomaly was Dark matter. As the features of gravity expressed in Relativity are considered to be correct the theory for Dark Matter was built within this framework. However ther are alternate theories to Dark matter which try to explain the difference in the movement of galaxies. Such as f(R) gravity( as taken from the link you gave). Even this theory closely follows General relativity. ( the exact mathematis is quite complex and would need a lot more time for me to understand). So I wouldnt be able to comment on the exact difference between the two. So even if Dark Matter is false and f(R) gravity is true it would not prove Genral relativity wrong.
Second Dark matter was created within the framework of Relativity to explain the anomalous movemnt of galaxies not to explain Relativity itself. If Dark Matter is proven false it is a possibility that the underlying cause would also show Relativity to be false. But this does not mean it is a given that if Dark Matter is wrong Relativity is wrong.
Corwin: @ Yan
A photon is sometimes said to have no rest mass because a photon is never at rest... so we say it has "potential" mass. At the velocity of C a photon is pure energy, yet it is still considered a particle. A photovoltaic cell may absorb this energy and convert it into an electric current, but when a photon slams into an object and is not deflected, some of this energy is converted into inertia, or Kinetic Energy.
i.e. Light "pushes" on things.
Energy and mass are equivalent (E=mc2)... since a photon is most decidedly a particle with energy, it must have a "potential" or "relativistic" mass... or Mrel.
In special relativity, it turns out that we are still able to define a particle's momentum p such that it behaves in well-defined ways that are an extension of the Newtonian case. Although p and V still point in the same direction, it turns out that they are no longer proportional... the best we can do is relate them via the particle's "relativistic mass" Mrel. Therefor...
p = MrelV .
Our best estimate to date, is that the likely maximum Mrel of a photon is 7 × 10 −17 eV.
Unimaginably small... but there it is.
Seriously dude... I learned this stuff in the 7th grade.
Hooray for the Canadian education system.
(Edited by Corwin)
CoIin: @ Yan
I think we're really saying the same thing conceptually but using different words. Anyway, let's not labor the point...
@ "... it would not prove Genral relativity wrong. "
"If Dark Matter is proven false ... "
I see this kind of misconception all the time. It is logically impossible to "prove" a theory wrong (or right, for that matter). This can be easily demonstrated. It's not controversial.
The wave theory of light and the phlogiston theory of combustion were never "proven" wrong; they are just not believed to be true anymore. (I always find the parallels between religion and science fascinating. Zeus has never been proven not to exist either. It's just that his ratings are kinda low right now )
Scientific theories are all interconnected as part of an organic whole, hence the term "scientific holism". No theory can be tested independently, in isolation from the others. Therefore, when any particular theory is under test, and the results are not what you expected (i.e. certain evidence is inconsistent with the theory), if you're determined enough it is ALWAYS possible to save your most cherished hypothesis/theory if you're willing to make radical enough adjustments to the entire "web of belief" (Quine's metaphor).
Logic itself cannot dictate how praise and blame should be distributed throughout the various hypotheses/theories in the network.
If you posit unknown forces that slow down time and shrink meter sticks, you can salvage Newtonian mechanics. You could even maintain that the Earth is flat if you did enough modification to the rest of the system.
The consistency of general relativity is currently being maintained by the ad hoc hypotheses of dark matter and dark energy, just as the laws of conservation of energy and momentum were "saved" by positing the neutrino.
Your neutrino bone's connected to your thigh bone
Yan26: @ Corvin - You are taking my original statement out of context. My original statement was
"E=MC^2 In this equation c is the speed of light through vaccum and is a constant. So if F increases the M has to increase. as M increases the speed becomes slower so you have to put more force which in turn increases M.Which means the Force required to push even a Hydrogen nucleus into light speed would be very high or infinite. Photons are considered massless I believe."
Now consider the fact that physicists cannot accelerate a single quark or gluon or similar sub atomic particles to light speed because they dont have enough power to do it but we can generate light simply by lighting a match.
Whats the difference between the two scenarios.
If you take a quark( or any other particle) and try to make it reach the speed of light what you are doing is accelerating it. Where the initial velocity u=0 and final velocity v=c( speed of light) This acceleration requires force . As you increase force the mass increases which means you require more force which further increases the mass.( This effect practically takes place only as you approach the speed of light which is why we dont experience it)
However in the case of lighting a match ( or any other instance of producing light) the photon is produced instantly . It is not accelerated. This would not be possible if the photon had mass. It would have to be accelerated. The photon doesnt have a mass . It is released as simply energy and therefore is simply released at light speed without acceleration. So while a photon does have potential mass in this case the photon acts mass-less.
That was my point. It simply referred to the behavior of a photon in this particular example as per my understanding.
lori100: interesting article related to relativity------Extremetech--------Physicists create world’s first multiverse of universes in the lab-----------Researchers at the University of Maryland, College Park and Towson University are reporting that they have created multiple universes inside a laboratory-created multiverse — a world first.
To be exact, the researchers created a metamaterial — like those used to fashion invisibility cloaks — that, when light passes through it, multiple universes are formed within it. These universes, called Minkowski spacetimes, are similar to our own, except they more neatly tie up Einstein’s theory of special relativity by including time as a fourth dimension.
While this is rather extraordinary, the experimental setup is actually quite simple — though definitely rather unconventional. The multiverse is created inside a solution of cobalt in kerosene. This fluid isn’t usually considered a metamaterial, but lead researcher Igor Smolyaninov and co found that by applying a magnetic field, the ferromagnetic nanoparticles of cobalt line up in neat columns. When light passes through these columns, it behaves as if it’s in a Minkowski universe.
-----------To create multiple universes, the researchers fine-tuned the amount of cobalt in the fluid until there wasn’t quite enough to form the nanocolumns. Natural variations in the fluid mean that some regions still have enough cobalt to form the columns, and thus new universes. As the fluid moves the columns collapse, multiple universes constantly pop in and out of existence.
There are two key takeaways here: First, metamaterials are usually rather hard to manufacture — and yet here the researchers have seemingly discovered a self-organizing metamaterial. Second, this is the first ever time that new universes have been created in a laboratory setting. This is about as bleeding-edge as it gets, so we’re not exactly sure what avenues of research this opens up, but Smolyaninov suggests that they could be used to study how particles behave in universes with different properties than our own. Our universe has fairly firm rules on how particles behave, but it might be interesting to create a pet universe where, say, photons have mass and light travels really slowly.