That was a good video. I'll bear that in mind next time this comes up. It came up the other day on another thread, and I struggled to give an answer, see this post and this. Also check out photon effective mass. IMHO the main thing to remember is that for a photon E=hf applies. It's a wave. Not some billiard-ball thing. It takes all possible paths like a seismic wave shakes all the ground.Cheezle said:
At Rest with our Hubble view
- Thread starter quantum_wave
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The video was just posted yesterday on the Sixty Symbols youtube account. I knew I had read a discussion somewhere here about the subject but I could not remember where. So this thread seemed like a likely candidate.
What you are saying here just sounds wrong. A photon can be emitted, travel a long distance and be absorbed by a single atom, and yet seems to follow all possible paths. That is very unlike a seismic wave.
[video=youtube;_7OEzyEfzgg]http://www.youtube.com/watch?v=_7OEzyEfzgg[/video]
In a now-classic quote, Richard Feynman described wave-particle duality as “the only mystery of quantum mechanics.”
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Markus Hanke
Registered Senior Member
Well, for example one could start by allowing connections other than the Levi-Civita connection in the theory, thus abandoning some of the symmetries of the curvature tensor and allowing torsion to be non-vanishing. Einstein-Cartan theory then comes to mind; the obvious advantage is that it avoids singularities, and also that it allows us to model gravitational spin-orbit coupling, which classic GR can't do. I think ECT is a perfectly reasonable extension/generalization of GR.
It might sound wrong, but E=hf does apply to a photon, it really isn't a point particle. It's definitely a wave. What's very wrong is the idea that a photon is some kind of point-particle, followed by amazement that the photon is miraculously in two places at once therefore we live in a multiverse. The issue of it being absorbed by a single atom is there because people think atoms are point-particles. You can diffract even buckyballs, they have a wave nature too.
Re the Dennis Crossley excerpt:
In a now-classic quote, Richard Feynman described wave-particle duality as “the only mystery of quantum mechanics.” It is, indeed, a mystery when you picture elementary particles using the point particle model.
Agreed.
In classical physics all of the objects of nature were divided into two categories, particles and waves. Matter was understood to be made of discrete particles while light, for example, was understood to be purely a wave phenomenon. The quantum revolution blurred the boundaries between these two categories and eventually merged them into a single category of wave/particles (or particle/waves or “wavicles” - the awkward nomenclature reflects our lack of understanding of what these things really are). Nevertheless, the particle concept continues to dominate our thinking about the nature of elementary particles.
And it's the wrong concept. You can make an electron (and a positron) out of light in pair production, you can diffract it, it's got a magnetic dipole moment, and the Einstein-de Haas effect "demonstrates that spin angular momentum is indeed of the same nature as the angular momentum of rotating bodies as conceived in classical mechanics". In atomic orbitals electrons "exist as standing waves", and after annihilation you've got light again. So what is the electron? A mystic enigmatic "fundamental" point particle? No. It's a wave going round and round in a closed path in the guise of a standing wave. You started with a field variation, a wave propagating linearly at c, you turn it into a standing wave with a standing field x 2, then back into a wave propagating linearly at c.
The current state of understanding of fundamental particles is that particles exist but somehow (mysteriously) have wave properties associated with them. This approach leads to the many mysteries of quantum theory (and, incidentally, also relativity theory) which to this day remain unresolved. The classical concepts are clearly inadequate here because the fundamental properties of particles and waves appear to be mutually exclusive. No one has yet been able to answer the question “How can a particle have wave-like properties?”.
By being a standing wave. I see Dennis Crossley refers to circulating waves. Thanks for bringing his paper/essay to my attention.
That essay is from the fxqi website. The quality of essays there is highly variable and I would not put too much value on them. I was just looking for a particular Feynman quote and that popped up in google. I was still editing when you reply and I had decided to remove most of the quote (first paragraph) when I realized what the essay was saying. I just wanted the Feynman quote. My point is really just that photons are not really waves as the Feynman video illustrates.
Photons are most definitely not like seismic waves. I suspect that when you said that, you had some mental image in your mind of what you meant that was not communicated in your post. I doubt you think that seismic waves and photons are alike. At least I hope you don't. After some thought I came up with a nuanced way that might explain what you meant. But really that is in my head and I have no idea it it matches what you meant. That is a common characteristic of alternative theories such as yours and quantum_wave's. Most of these types of theories are built inside the theorist's head using what many alternative theorists call intuition or common sense. I have found that people's intuition and common sense is often dead wrong. I think I will stick with the Feynman explanations.
As far as a variable speed of light goes, it seems very unlikely. Note on Varying Speed of Light Cosmologies. You mentioned that for the two clocks in your gif that one time slows down. If you think about it that is very incorrect language. Time has no speed. It can't slow down. This idea seems to come out of psychology where perception of time changes. But if time could be said to have a speed it would be 1 second per second. What you should have said is that time dilates. Time dilation has a different definition than "slowing down".
Wikipedia:
What you really seem to be saying is that perceived time (physical clocks of all types) is variable and that there is some kind of background time that is the real time. And that photons being physical experience this slowing of clocks as though they are moving in molasses, compared to the background of real time. Of course there is no evidence for that. You seem to be saying that physical systems are all slowed near massive objects. And of course this is all because of aether. It is all very problematic and not something I would ever buy into.
Markus Hanke
Registered Senior Member
You are certainly not the only one with this opinion.
And I guess my point is that they really are.
I'm a Feynman fan, and he was known as "The Great Explainer". But some of his explanations aren't that great. A while back we were talking about his non-explanation of a magnet. And E=hf isn't my intuition. The f is for frequency.
With respect Cheezle, I didn't say that time slows down at all. I said clocks feature some kind of regular cyclical motion. When that motion goes slower the clock goes slower. Whether it's a mechanical clock or a quartz wristwatch or an optical clock, that's it.Cheezle said:
I'm not saying that. I'm pointing out what Einstein said and how it's different to the way GR is usually described.Cheezle said:
A worse sin, however, is to lie about one's ability to understand physics and try to convince other people that one's fantasy physics is correct. You certainly seem to be taking this approach. Unless you would care to show us how inhomogeneous space plays a role in galactic rotation curves?
Or perhaps you would like to lie some more about how you answer every question?
So? Depending on context, "space" could mean anything from three-dimensional space to four-dimensional spacetime to some abstract n dimensional space (e.g. as in phase space, for instance). Particularly in a non-technical exposition like the Leyden address, it is quite specious and even dangerous to assume Einstein was being precise about everything.
It's not that precision isn't important in physics (it is), but you're looking for it in absolutely the wrong place.
No, your disagreement has been over whether one can and should understand general relativity as a theory based around the idea of inhomogeneous space (or something to that effect).
I've been over this with you before. Nobody is confused about the distinction between space and spacetime. It's not even realistically possible for anyone who has learned general relativity on a mathematical level, since the difference is very clearly spelled out. It's rather you who can't seem to wrap your head around the facts that:
- the linguistic and terminology conventions routinely used by physicists are not always equally precise, nor do they need to be (precisely because the distinction between space and spacetime is obvious),
- the distinction between space and spacetime is not always relevant to the point being discussed, and
- we're not going to idiot-proof our posts just to force you to address the point we're actually making.
So why do you think that the standard interpretation of GR is different from yours? Is it a conspiracy? Everybody is reading the same documents. It seems to be a you against the world type argument which is never something to bet on. Is it because you are smarter than everybody else?
Who, precisely, thinks the photon is some "billiard-ball thing"?
Markus Hanke
Registered Senior Member
You couldn't be any more right. But then again, this is Farsight we are talking about...he has been at this for years on a number of forums, and hence already has a reputation. His carry-on is hardly surprising. He wouldn't even know how to calculate his own pants size ( notice the way he avoids any maths-related questions ? ), yet he thinks he has some unique deep insight into Einstein's mind. As such he fits quite well into the legion of cranks who march through all the various forums day after day, never to be heard from again after they been shown the door. The only difference is that Farsight sticks around longer than most others.
If Farsight has truly been acting like this for several years, why on earth hasn't he simply learnt GR by now? If you can do calculus (and are willing to ignore much of the detail) then it's possible to get a loose grasp on GR, e.g. solve reductions of the geodesic equations for some physically interesting scenarios. It would at least be a start!
Farsight, you must realise that your approach is totally unscientific. All your arguments are muted if you're not allowed to simply say "it's true because Einstein said" or link to websites. You've been honest enough to admit as such. If you've been doing this for a prolonged period of time, while not bothering to learn even the most rudimentary parts of GR, then your behaviour is reprehensible.
Markus Hanke
Registered Senior Member
Because he knows that the material to be learned would contradict his believes, and all the things that he has been saying on so many forums over so many years. To the best of my knowledge he has also self-published a book, and has appeared on a fringe-science TV show with this stuff. Learning and acknowledging what GR is really about would be the ultimate loss of face to him, so he will never do it. He has basically trapped himself with no way forward and no way out. It's quite a sad situation, really. Of course there's always the option of simply owning up, and saying "Look guys, I made a mistake here, I was wrong...and this is what I am going to do to fix it". But somehow I don't think that will ever happen, I think he is quite comfortable in his little "me against the world of misguided mainstream science" niche.
Beach
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The accommodation of the consensus is a practical tactic that will always be an influence in the scientific community.
GR readily accommodates expansion or contraction, and when the CMB came along Inflationary Theory was added to the consensus cosmology because it had to be. And someone will have predicted them and will be applauded for the foresight. At the same time, many predictions will be falsified, and forgotten.
As the visible horizon expands, new discoveries will be made and the consensus cosmology will accommodate them because it must.
Interestingly, Marcus and I indirectly discussed the time delay of gravity a few months ago on a distant thread. The topic had to do with gravitational time delay, which I portrayed as a universal effect. He pointed out that the consensus was that gravity in normal motion has nothing to do with time delay. It is the curvature of space-time that determines the motion of bodies. I pointed out that there is a time delay in the consensus theory when changes to the determined motion occur, as in when bodies collide. He acknowledged that particular invocation of time delay, and I later associated it with Shapiro delay. I remain uncertain why the time delay doesn't apply to normal motion, but I guess then we wouldn't need curved space-time, we would need some mechanism for action at a distance.
Admittedly I haven't learned your particular perspective as evidenced by the fact that I surmised that you see a mechanism other than the geometry of space-time that causes gravity. It is my fault or at least my inclination to try to draw a clear line of distinction between two main perspectives, the geometry of GR and the mechanism of action at a distance.
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I've read my share of the popular media, including Isaacson's "Einstein - His Life and Universe". And from that perspective you are right. Without a Cosmological Constant it seems that the universe must either expand or collapse, since any dynamics at all would upset the balance; the pencil can't stand on its point unless everything around it remains static. That was the point I am making by highlighting the raw redshift data, Einstein was a genius. I guess he did portray the CC as a blunder, but wasn't the timing of that declaration after Hubble? If so, declaring it a blunder really pointed out that he was accommodating the consensus by putting in a factor to account for their belief that the universe was static.
The accommodation of the consensus is a practical tactic that will always be an influence in the scientific community.
GR readily accommodates expansion or contraction, and when the CMB came along Inflationary Theory was added to the consensus cosmology because it had to be. And someone will have predicted them and will be applauded for the foresight. At the same time, many predictions will be falsified, and forgotten.
As the visible horizon expands, new discoveries will be made and the consensus cosmology will accommodate them because it must.
http://en.wikipedia.org/wiki/Shapiro_delay
Interestingly, Marcus and I indirectly discussed the time delay of gravity a few months ago on a distant thread. The topic had to do with gravitational time delay, which I portrayed as a universal effect. He pointed out that the consensus was that gravity in normal motion has nothing to do with time delay. It is the curvature of space-time that determines the motion of bodies. I pointed out that there is a time delay in the consensus theory when changes to the determined motion occur, as in when bodies collide. He acknowledged that particular invocation of time delay, and I later associated it with Shapiro delay. I remain uncertain why the time delay doesn't apply to normal motion, but I guess then we wouldn't need curved space-time, we would need some mechanism for action at a distance.
True, but going straight in space can still be under the influence of curved space-time, if you are a GR advocate. A straight line is a condition within the scope of all possible paths in space-time, I would think. Personally, photons having mass would be a good explanation for why light can't escape a black hole. Gravity would just have to be strong enough to attract photons when the mass of the attractor reaches some threshold, as it would around a black hole.
It is not necessarily that they believe what they are taught, or that they can't think for themselves. They just want to be sure that those with alternative ideas understand the consensus before they go off the grid. The problem is that there is no scientific criteria to allow permission to go off the grid, lol.
I see space-time/GR as theory that is internally consistent and not inconsistent with observational evidence. I don't see it as perfect and it does not precisely correspond to "reality" though obviously I haven't been granted "permission" to say that, ha ha.
Admittedly I haven't learned your particular perspective as evidenced by the fact that I surmised that you see a mechanism other than the geometry of space-time that causes gravity. It is my fault or at least my inclination to try to draw a clear line of distinction between two main perspectives, the geometry of GR and the mechanism of action at a distance.
No, I think I am beginning to see your perspective. Einstein's EFEs are not the sum total of GR, and the greater body of understanding that is GR is not as cut and dried as the equations themselves. Someone just pointed out that there are differing views, but you don't seem to have "permission" to go there :shrug:
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A comment on this:
The mathematics of general relativity summarises everything it predicts and everything that is testable about the theory, so it follows that anything you might try to add to that is untestable and would not normally be regarded to have scientific merit.
On the subject of views and interpretations, the mathematics of general relativity is obviously, to anyone who has had much exposure to it, the Riemannian geometry of curved spacetime that you've already heard about. There seems to be little room for differing views in this.
Of course that doesn't mean that a very different interpretation might not be possible, but that would require a level of justification far beyond anything Farsight has been able to provide in the years he's been posting here and elsewhere. Physics just isn't advanced based on GIF images and a collage of selected quotes from celebrities in the field. It simply doesn't work that way.
The mathematics of general relativity summarises everything it predicts and everything that is testable about the theory, so it follows that anything you might try to add to that is untestable and would not normally be regarded to have scientific merit.
On the subject of views and interpretations, the mathematics of general relativity is obviously, to anyone who has had much exposure to it, the Riemannian geometry of curved spacetime that you've already heard about. There seems to be little room for differing views in this.
Of course that doesn't mean that a very different interpretation might not be possible, but that would require a level of justification far beyond anything Farsight has been able to provide in the years he's been posting here and elsewhere. Physics just isn't advanced based on GIF images and a collage of selected quotes from celebrities in the field. It simply doesn't work that way.
Are you discussing Teleparallelism? Avoids what kinds of singularity, coordinate singularity found in the Schwarzshild solution or the real singularity whose description is outside the GR domain of applicability?
Most every comment Farsight makes is a bullshit interpretation of science he knows nothing about. This is a derivation of the natural phenomena the Shapiro Delay experiments describe.
The time the light takes to traverse the path is recorded on the remote bookkeepers clock. I'll give you an example. I'll use light emitted at the surface of the Sun and received on Earth. For conveniece we can say the path of the light is the shortest distance between emission and reception. So the path being analyzed is completely radial.
The remote radial coordinate speed of light
dr/dt = (1-2M/r)
You can integrate this over the path and build a formula for predicting the Shapiro delay. For our case
dt_bkkpr=(r-2M) + 2M ln (r-2M)
So for the chosen path light emitted from the sun photosphere received on Earth
dt = [r_earth orbit - r_sun] + 2M_sun ln[r_earth orbit/r_sun]
The 1st component is the distance between where the light is emitted and received and the 2nd component is the predicted Shapiro delay due to a path through curved spacetime.
I'll solve it for our case
r_earth orbit = 1 AU = 1.495978E11 m
r_sun = 6.9598E8 m
M_sun = 1477 m [using geometric units]
dt_bkkp = [ 1.495978E11m - 6.9598E8m] + 2954m ln[1.495978E11m/6.9598E8m]
= 1.4890182E11m + 15854.11645m = 1.489018359E11m
15854.11645m is the delay time in geometric units. dt_meter.
To convert this to seconds divide by c.
dt_second = 15854.11645m/2.99792458E8m/s
= .00005288367752 second
~ 53 microsecond
That is the extra time due to the path through curved spacetime.
Just to help with understanding. The first component r-2M is the distance the light would travel if the path was over flat spacetime. The 2nd component is the extra distance the light travels because the path of the light has spacetime curvature. The delay.
Because Farsight doesn't have a working understanding of this physics he makes up bullshit based on ignorance. The fact you could agree with his nonsense means you should study the actual physics if you really want to know. EVERYTHING that GR predicts are essentially derived from the EFE. I would be inclined to use the metric solutions to this set of equations because they're real easy to use. The metric solutions are the same thing. The comment that the EFE doesn't embody all of GR is complete nonsense. Whoever said that needs to review critical thinking as in logic.
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Markus Hanke
Registered Senior Member
I was referring to Einstein-Cartan gravity. It can be shown that if torsion is allowed to be non-vanishing in the context of this model, gravitational singularities ( both at the BB, and "inside" black holes ) cannot form. Furthermore it provides a natural mechanism for gravitational spin-orbit coupling, and implies that fermions must be spatially extended, eliminating the QFT problem of ultraviolet divergences. There are also cosmological implications in that the Big Bang is replaced by a "Big Bounce".
I realize that currently there is no experimental evidence on the basis of which to choose Einstein-Cartan gravity over GR ( and I am not advocating such a course of action ), but I still think it is nonetheless a very interesting and viable alternative / extension to GR.