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Thanks for taking a look, I'll have to take another look and see if that's what he did but if so I'm not sure how that works because you need at least two points for a length so how could one even try to calculate a length contraction from a single point?
originally posted by: delbertlarson
In fact, I know this because of a similar error I made in my early days. I wrote to John Bell about a theory I had that there was no length contraction, as I had derived equations showing how everything came about from time dilation alone. John Bell wrote back to tell me he didn't see how a length contraction could come out of time dilation, and I realized I had done the calculations at a single point (just like the author you referred me to). Once I did things at two separated points it got a lot more difficult.
I suppose you and I see different lessons in that, because I don't think it shows that "Theory is not going to provide much of the road to new physics" at all and I'm surprised you'd say that. All it shows is that it didn't happen in that one example, it says nothing about what will happen in other cases. I could cite more examples, like the Pioneer anomaly, which also created "new physics" ideas to explain the phenomenon, but again in that case it turned out the anomaly wasn't really an anomaly after a more detailed analysis, so it just shows that people tried creating or applying new theories where no new theories were really needed. This doesn't tell me anything about people creating new theories where they really are needed, and most physicists seem to agree we need better models for black holes and the earliest part of the big bang.
originally posted by: mbkennel
a reply to: Arbitrageur
I would worry more about experiments than theory.
Consider the recent diphoton hump. Two lhc experiments showed a potential excess of events. Over a year, theorists wrote 700 papers on this, with perhaps 250 varying theoretical proposals, of which maybe 50 could be quite theoretically plausible. (Just a guess).
So they took more data, and after a year, the bump went away, it was just an unusual coincidence. Theorists were plenty creative.
Theory is not going to provide much of the road to new physics, thats the lesson. Mathematical consistency and beauty is not enough.
I've never seen any coherent "theory" from you and as I said I could write an entire book about what's wrong with your experiment, but in fact even more carefully performed experiments are still subject to experimental error and other problems so I find enough reason to worry about some theories and some experiments. The amount of worry varies depending on the specifics of the theory or experiment. I haven't seen much reason to doubt Newtonian mechanics at non-relativistic velocities so I don't worry about those experiments for example, but as my signature implies not only do I worry about string theory, I don't think it's really a theory, at least not yet.
originally posted by: Nochzwei
exactly right
We don't imagine the geometry of the universe to work this way, and it's better to think of the big bang as occurring "everywhere in the universe at once" instead of at a single point. We've never seen the outer edges of the universe; we can only observe the observable universe which is a smaller sphere then the entire universe, as far as we know.
originally posted by: DanDanDat
If the big bang occurred at a singular point in … what every existed before the big bang; and all mater emerged from that spot and has expanding outward ever since…
where exactly does our galaxy sit in that expanding sphere of our universe?
For example are we at the exact center (where the big bang occurred)? … I would imagine not. Or are we at the outer most shell of the universe? … again I would imagine not. So where between the center and the outer shell are we?
No.
… that we can see light from galaxies that left their galaxies 13.1 billion years ago (700 million years after the big bang); shouldn’t we be able to look in the exact opposite direction and see the end of the universe?
You are correct, there's not. As far as the experts can tell there is at least 46.5 billion light years in all directions, which is the radius of the observable universe, the edge of which is receding at over 3 times the speed of light, and accelerating. We don't know what's beyond the observable universe and whether the universe has any edges or not, it might not. In fact we don't even know if the universe is finite or infinite in size. Flatness measurements show the universe is fairly flat which tends to imply an infinite size but due to measurement limitations this doesn't rule out a very large finite size.
With the age of the universe being around 13.82 billion years; there can’t be 13.82 billion years of distance in all directions from our current location.
Today the diameter of the observable universe is estimated to be 28 billion parsecs (about 93 billion light years). This diameter is increasing at the rate of about...6.5 times the speed of light...
Thanks for taking a look, I'll have to take another look and see if that's what he did but if so I'm not sure how that works because you need at least two points for a length so how could one even try to calculate a length contraction from a single point?
I don't see many others making his claim the models are identical, but he does cite other sources saying the models are experimentally indistinguishable. I understand your position is they be experimentally distinguishable, but we just haven't performed the right experiment yet to demonstrate the difference, so until we have an experiment to demonstrate the difference, the "experimentally indistinguishable" claims he cites haven't been falsified.
Light is just a transverse wave on the solid aether, a photon just a wave packet in the aether, and the aether is essentially just two infinite seas of charge interacting with each other.
(Note that Dirac proposed a single sea; it turns out there are two.) Static electric force results from a bit of the sea being separated out, which then displaces the like charges making up the sea, and forces on charged particles result from such displacements. Magnetism is more complicated, and is best explained through the vector potential in the model.
I believe the major problem in physics is relativity. It leads to a requirement of point-like particles, which in turn leads to infinities which cannot be handled well.
The concept of relative simultaneity also presents problems with regard to understanding Bell's theorem results.
Other problems are the abandonment of objective reality and the abandonment of underlying physical modelling by modern physics, which has been replaced by a search for terms in a Lagrangian. (Physics is devolving into pure math, with no physical modeling anymore.) These abandonments have also come about because of relativity, in order to save relativity from Bell's theorem tests.
As for my own challenges: 1) My theorizing at the moment does not handle gravity at all - I have never studied it;
2) My ABC Preon Model so far has not calculated lepton masses, nor quark masses, nor does it have a sufficiently strong theoretical underpinning (it is just a good high level model at this point);
As an example of entanglement we can consider a wave-function that contains two photon wave packets within. One photon goes one way, the other the opposite way. But the wave-function encapsulates both, and, for this example, we will say that the total spin is zero. Within the individual packets the spin is unmeasured, and by my philosophy the spin has a spread of values within each packet. Upon measurement of one packet the spread of the spin is reduced by the measurement, and at that instant the spin of the other packet is also collapsed due to the constraint of zero total spin. At that point the two wave packets are now almost completely separate and independent entities, since momentum has also been transferred in the detection process and this collapses the position spread of each photon such that there is essentially zero overlap between the two photons. They are no longer entangled after the measurement.
The above description is viable in a world where we have an underlying objective reality and an absolute simultaneity. However, it is not viable if we accept relativity. The above description is a simple and clear way to model the quantum world, it is consistent with all known experiments, and it can appeal to our common sense. We need only set aside relativity and return to an absolute theory of space and time to make sense of these things.
The collapse itself is something that is different from physics in the classical realm. Essentially, a portion of the wave-function disappears and the remainder is increased in its magnitude. And the process must happen at speeds much faster than the speed of light. It would be fascinating if we could arrange for experiments internal to the wave-function, but at the present time such efforts are beyond what we can do. While it may be fun to speculate about the internal goings-on, it isn't really science unless our speculations lead to tests we can do.
originally posted by: delbertlarson
The uncertainty principle. My view of the uncertainty principle is that it is a representation of the spread of things, not a representation of an uncertainty. If we have a wave packet of light, within that packet we will have a spread of frequencies. This is well known classically by doing a Fourier analysis of the packet. That spread of frequencies is equivalent to a spread of momenta, and there is also a spread in the spatial size of the wave packet. There is nothing really uncertain about it. The idea of an uncertainty principle, in my opinion, only arose from the philosophy of believing in a point-like electron residing probabilistically within the wave-function. But if we instead view the wave-function as the square root of the density of an electron cloud, then there is no uncertainty at all. It is just a description of the elemental size of things.
originally posted by: delbertlarson
Einstein's more radical approach stipulates that time itself changes as an observer moves, and I've never believed that made much sense. However, as physicists, we must set aside what we think is sensible and reduce any theory to experimental tests. And on that score there are very few tests that can separate the Einstein and Lorentz theories.
There has been an experiment to see if antimatter would fall toward Earth like regular matter or be repelled from Earth, and it behaved like matter gravitationally, so I think that question about anti-matter is answered.
originally posted by: ATSAlex
I have a question for the physics experts, We have matter and anti matter, we have mass but is there negative mass (anti-mass) ? Would that be the remaining invisible mass in the universe, just matter but with negative mass?
You're going to get the college freshman answer, not the graduate student answer. Photons don't have mass.
originally posted by: ATSAlex
Another question, do photons have mass? since mass and energy are related they must have mass, and if they have mass how come they can travel at the speed of light since according to Einstein equation their mass should grow exponentially, can an object with "negative mass" or anti-mass be bound by that same restriction or do negative mass objects are exempt of Einstein's equation and therefore can travel at much faster speeds than light?
Photon pairs generated via SPDC are useful for studying the fundamental physics governing correlated particles. A thorough understanding of the underlying physics enables the use of correlated particles in numerous applications, ranging from metrology to encryption. In particular, it is interesting to study how these correlated photons can be generated in a microgravity environment and to demonstrate that their correlations are preserved even after the photons have travelled through a changing gravitational field. This enables correlated photon technology to be deployed even in a space-based environment. This mission on the NanoRacks-GOMX-2 satellite is designed to be a technology demonstration to show that it is possible to generate quantum correlated photon pairs in space using the CubeSat platform. If successful, it will pave the way for more ambitious experiments where correlated photons are beamed between platforms (space to ground) or (space to space) so that the correlations can be investigated over large distances.
Experimental checks on photon mass[edit] Current commonly accepted physical theories imply or assume the photon to be strictly massless. If the photon is not a strictly massless particle, it would not move at the exact speed of light, c in vacuum. Its speed would be lower and depend on its frequency. Relativity would be unaffected by this; the so-called speed of light, c, would then not be the actual speed at which light moves, but a constant of nature which is the maximum speed that any object could theoretically attain in space-time.[23] Thus, it would still be the speed of space-time ripples (gravitational waves and gravitons), but it would not be the speed of photons. If a photon did have non-zero mass, there would be other effects as well. Coulomb's law would be modified and the electromagnetic field would have an extra physical degree of freedom. These effects yield more sensitive experimental probes of the photon mass than the frequency dependence of the speed of light. If Coulomb's law is not exactly valid, then that would allow the presence of an electric field to exist within a hollow conductor when it is subjected to an external electric field. This thus allows one to test Coulomb's law to very high precision.[24] A null result of such an experiment has set a limit of m ≲ 10−14 eV/c2.[25] Sharper upper limits on the speed of light have been obtained in experiments designed to detect effects caused by the galactic vector potential. Although the galactic vector potential is very large because the galactic magnetic field exists on very great length scales, only the magnetic field would be observable if the photon is massless. In the case that the photon has mass, the mass term [displaystyle scriptstyle [frac [1][2]]m^[2]A_[mu ]A^[mu ]] scriptstylefrac[1][2] m^2 A_[mu]A^[mu] would affect the galactic plasma. The fact that no such effects are seen implies an upper bound on the photon mass of m < 3×10−27 eV/c2.[26] The galactic vector potential can also be probed directly by measuring the torque exerted on a magnetized ring.[27] Such methods were used to obtain the sharper upper limit of 10−18eV/c2 (the equivalent of 1.07×10−27 atomic mass units) given by the Particle Data Group.[28] These sharp limits from the non-observation of the effects caused by the galactic vector potential have been shown to be model dependent.[29] If the photon mass is generated via the Higgs mechanism then the upper limit of m≲10−14 eV/c2 from the test of Coulomb's law is valid. Photons inside superconductors do develop a nonzero effective rest mass; as a result, electromagnetic forces become short-range inside superconductors.[30]
originally posted by: Phantom423
If photons have no mass, why are they effected by a gravitational field?
I found this explanation of "massless photons" which says that photons develop "nonzero effective rest mass" in a superconductor but the article doesn't talk about photons in a gravitational field.
originally posted by: Bedlam
originally posted by: Phantom423
If photons have no mass, why are they effected by a gravitational field?
I found this explanation of "massless photons" which says that photons develop "nonzero effective rest mass" in a superconductor but the article doesn't talk about photons in a gravitational field.
Alex, the question is "What is the stress-energy tensor?"
I'd like Post Graduate Modern Physics for $200, please.
originally posted by: Phantom423
??
It doesn't. Bedlam is right as usual of course but here's the dumbed down explanation, where he claims we are all "lied to" in school which is probably true depending on your point of view, but it's not a very big lie because in normal circumstances the gravitational effect of a photon is negligible meaning not exactly zero but it's so close you can't typically measure it as being different from zero:
originally posted by: Phantom423
So how does a photon transition from having no mass to having some mass?
originally posted by: Arbitrageur
where he claims we are all "lied to" in school which is probably true depending on your point of view...
Why aren't you asking about neutrinos instead, which probably do have a tiny mass...