CREDIT Purple Mountain Observatory, Chinese Academy of Sciences
A new way to test one of the basic principles underlying Einstein’s theory of General Relativity using brief blasts of rare radio signals from space called Fast Radio Bursts is ten times, to one-hundred times better than previous testing methods that used gamma-ray bursts, according to a paper just published in the journal Physical Review Letters. The paper received additional highlighting as an “Editor’s Suggestion” due to “its particular importance, innovation, and broad appeal,” according to the journal’s editors.
The new method is considered to be a significant tribute to Einstein on the 100th anniversary of his first formulation of the Equivalence Principle, which is a key component of Einstein’s theory of General Relativity. More broadly, it also is a key component of the concept that the geometry of spacetime is curved by the mass density of individual galaxies, stars, planets, and other objects.
Fast Radio Bursts are super-brief blasts of energy — lasting just a few milliseconds. Until now, only about a dozen Fast Radio Bursts have been detected on Earth. They appear to be caused by mysterious events beyond our Milky Way Galaxy, and possibly even beyond the Local Group of galaxies that includes the Milky Way. The new technique will be important for analyzing the abundance of observations of Fast Radio Bursts that advanced radio-signal observatories, now being planned, are expected to detect.
“With abundant observational information in the future, we can gain a better understanding of the physical nature of Fast Radio Bursts,” said Peter Mészáros, Holder of the Eberly Family Chair in Astronomy and Astrophysics and Professor of Physics at Penn State, the senior author of the research paper. Like all other forms of electromagnetic radiation including visible light, Fast Radio Bursts travel through space as waves of photon particles. The number of wave crests arriving from Fast Radio Bursts per second — their “frequency” — is in the same range as that of radio signals. “When more-powerful detectors provide us with more observations,” Mészáros said, “we also will be able to use Fast Radio Bursts as a probe of their host galaxies, of the space between galaxies, of the cosmic-web structure of the universe, and as a test of fundamental physics.”
The impact of the new method using Fast Radio Bursts is expected to increase significantly as more of the bursts are observed, and if their origin can be established more firmly. “If Fast Radio Bursts are proven to originate outside the Milky Way Galaxy, and if their distances can be measured accurately, they will be a new powerful tool for testing Einstein’s Equivalence Principle and for extending the tested energy range down to radio-band frequencies,” Mészáros said.
Einstein’s Equivalence Principle requires that any two photons of different frequencies, emitted at the same time from the same source and traveling through the same gravitational fields, should arrive at Earth at exactly the same time. “If Einstein’s Equivalence Principle is correct, any time delay that might occur between these two photons should not be due to the gravitational fields they experienced during their travels, but should be due only to other physical effects,” Mészáros said. “By measuring how closely in time the two different-frequency photons arrive, we can test how closely they obey Einstein’s Equivalence Principle.”
More specifically, Mészáros said the test that he and his coauthors developed involves an analysis of how much space curvature the photons experienced due to massive objects along or near their path through space. He said, “Our test of Einstein’s Equivalence Principle using Fast Radio Bursts consists of checking by how much does a parameter — the gamma parameter — differ for the two photons with different frequencies.”
Mészáros said his research team’s analysis of the less-than-a-dozen recently detected Fast Radio Bursts “supersedes by one to two orders of magnitude the previous best limits on the accuracy of the Einstein Equivalence Principle,” which were based on gamma rays and other energies from a 1987 supernova explosion, supernova 1987A. “Our analysis using radio frequencies shows that the Einstein Equivalence Principle is obeyed to one part in a hundred million,” Mészáros said. “This result is a significant tribute to Einstein’s theory, on the hundredth anniversary of its first formulation.”
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I just had Al Gore and Dana N on the ‘phone. They want me to ask you all to stop discussing real science. They’re starting to feel left out.
dbstealy, January 5, 2016 at 1:58 pm
“And it doesn’t answer why when I look in a mirror, my right and left arms are reversed, but my head and feet aren’t…”
I once tried to solve this mystery looking into the mirror by standing on my head, but darn… this time my arms weren’t reversed…
I have a better answer to this one.
An excerpt from my (unpublished) novel, The Catalyst of Moonlight:
“Gentlemen,” I said, “I will prove to you that the riddle itself is wrong: A mirror does reverse up and down, and doesn’t reverse right and left.
“If you place a mirror on the floor and stand on it, you will see your head beneath your feet. Ditto for the ceiling. This proves the first part of my assertion. Now, as for right and left, if I hold up my left hand before a mirror, my mirror image also holds up his left hand.”
“Nonsense, Orez!” the professor said. “He holds up his right hand.”
“Does he, Professor? Let’s look at it more closely. How do I and my mirror-image establish what is left and what is right? I will hold up my left hand and say to him, ‘This is my left hand,’ and at the same time he will be holding up the hand opposite mine in the mirror and be saying, ‘This is my left hand.’ There is no possible ambiguity–we both agree that the hand we hold up is our left hand, correct?”
“But Orez, what we mean when we say, ‘This is my left hand,’ is, ‘If you turn around and face the way I am facing, so front and back are reversed, then the hand you raise that is on the same side of your body as the hand I raise when I say ‘This is my left hand’ is your left hand.”
Celia giggled, then stopped abruptly as the Professor looked sternly at her.
“Why are you getting so complicated, Professor?” I replied. “Now you’ve said that in order to keep left and right straight, we have to reverse front and back. But that’s exactly what a mirror does! It reverses front and back! Not left and right! Look–if you wanted to see yourself as you actually are, pretend you’re three feet in back of your head. What would you see? The back of your head, of course. Your mirror-image preserves left and right but switches back and front: if you are facing north, your mirror-image faces south! The whole riddle is bogus, like everything Dodgson’s propounded!”
If my memory serves me right, this phenomenon once was a topic in the “Mathematical Games” section of Scientific American by Martin Gardner.
The fascinating dimension of this mirror phenomenon is, it is a perfect illustration of our blind spots when looking and studying the world around us. What we see and perceive is deeply influenced by our perspective and behavior we normally aren’t aware of as they are just plain routine, apparently self-evidence or fixed in belief.
Bogus or not, the simple answer eluded most of the solutions that were send to Martin (in those days it went by paper mail – somewhere in my archive I have an answer from Martin to a letter of mine, signed by Martin himself – great man).
Another more simple clue would be to look at a book in the mirror, with the book not turned around a vertical axis, as we would do by habit, but turned around a horizontal axis.
But then, maybe some mysteries should stay mysteries…
No Ronald; you have it all wrong.
What you call your “left” hand is by convention in reference to a co-ordinate frame, in which the direction YOU are facing is defined as the POSITIVE Z direction. Upwards would be POSITIVE Y direction, and to your right is the POSITIVE X direction.
Light that comes from YOU and heads in the positive Z direction will hit the mirror, and reverse ( IN Z). The chap in the mirror sees the light that appears to be leaving him, is travelling in your NEGATIVE Z direction, but in his conventional co-ordinate frame, that light is still travelling in HIS POSITIVE Z direction; the direction the HE is facing.
And referred to HIS co-ordinate frame, the hand you are holding up is on HIS RIGHT in HIS co-ordinate frame of reference, because that is HIS POSITIVE X direction.
You have to be consistent with your reference frames.
Take for example, the situation for a fly caster who is going to cast a fly line forward, which is his positive Z direction. So he is going to impart a positive linear momentum to the fly line, and the fly that it carries with it.
To do that, he brings his rod from a direction pointing backward over his head, in an upward arc, going up over his head, and then down in front of him So the fly line and rod tip, will also have an angular momentum, that is in a right handed clockwise direction, which by convention is the positive angular direction.
So that generally upward arcing line trajectory combines a positive linear momentum, with a positive angular momentum, and looks something like the tracks on a Tank, that is moving forward.
Now initially, the fly caster flipped the rod backward over his head along with the line, so he imparted a negative linear momentum to it. But the upward curving arc of the rod and line is now counterclockwise in the right hand screw frame, so it to is negative.
So you have both linear and angular momentum either positive or both of them are negative.
If you do it correctly the fly line will roll out in front of your like the tank track falling off the front of the tank.
If you mess up, and you let the rod tip bounce upward at the end of the cast, that will impart a negative angular momentum to that portion of the line at thast time in the cast, whereas the first part of the cast had ++ linear and angular momenta, and now you have +- linear and angular.
Those initially imparted momenta must be conserved once the casting stroke is finished so as the fly line unrolls in front of you, eventually the counterclockwise negative angular momentum, gets overtaken by the earlier launched positive angular momentum, and the fly line will tie itself into a knot right in front of your eyes, and it will all crash on the water in a mess.
It’s called a tailing loop, and it was all caused by that rod tip bounce, that resulted from your poor casting technique.
So you always have to keep your co-ordinate frames straight or you will create a mess somehow.
And your mess was to think your mirror buddy has the same frame of reference that you do.
He doesn’t.
g
Jurgen, as you mention in your later comment, if I understand it correctly, the correct answer has to do with our unstated assumption that the mirror is vertical.
I remember Martin Gardner’s column well. I used to have a book of his puzzles.
Mu!
The mirror doesn’t reverse anything. Your right hand is reflected on the right, your left on the left, top on top, etc. It is your expectation or a rotation that is wrong.
George E. Smith and E. M. Smith:
I agree with what you both say, and see no conflict with my explanation. The mirror doesn’t reverse right and left, it only appears to when we try to imagine ourselves as the man in the mirror, and also appears to reverse up and down if we put the mirror on the floor or ceiling.
The original riddle, which is earlier in my book, was “Why does a mirror reverse right and left but not up and down?” Perhaps I should have included that in my first comment.
Paragraph six seems to be saying that if the results don’t fit the theory something else must be messing with the results. Hmm.
So they are saying that as the signal passes through the plasma and dust surrounding galaxies and stars, there won’t be a refraction or diffraction effect that will cause different frequencies to travel at different speeds?… I’m not so sure of that. We’ve already had papers describing this refraction effect for light passing through the edges of galaxies… I’m pretty sure gamma ray refract/diffract too.
Measuring two different photons to see if they arrive at the same time is all very well, but who observed them leaving at the same time?
For those interested, some efforts to bridge the gap between GR and quantum theory hypothesize differences in how different wavelengths of light are influenced by gravity:
http://www.lightandmatter.com/html_books/genrel/ch02/ch02.html#Section2.4
Discreet quantum packets of space time, with nothing in between. True nothing, ie granular space time. Fun to think about. It may also resolve some of the issues regarding black holes where space time is assumed to be crushed out of existence, by some, due to infinite gravity at the supposed singularity, which I am still trying to understand how it could form since time stops there. It should take forever for it to form.
This is why Einstein is one of the couple of dozen scientists names we all know. None of the science ‘lites’ of the post normal period we are going through is going to make the cut.
These sub-threads can be confusing, so this is a new one replying to several others in various places upthread…
A very knowledgeably guy (who co-invented LED’s, IIRC) sent me the following points (paraphrased a little):
• Photons do have discrete frequencies.
• Photons and electrons aren’t remotely similar. Electrons are zero-sized point charges, and their electric field drops off with the inverse square law. So an electron needs to get relatively close to an atom for its field to interact by being captured and causing a reaction. There is a sort of target radius (cross-section), and if the electron gets inside that target, the reaction will occur; otherwise not. It’s like shooting at targets. The cross section is measured in ‘barns’ (10^-24 cm^2). ‘Barns’ comes from hitting the side of barn, because one barn is a quite large cross-section as nuclear reactions go; nanobarns or picobarns are more typical sizes.
• Nobody ever talks about how close a photon has to come to anything to react, as in ‘get captured’, for example. But as surely as a wave will hit the beach, the photon will hit the CO2 molecule and get captured, so the photon’s extent must be quite large; maybe meters, as laser beams can interfere over path lengths of several meters.
• CO2 molecules at 400 ppm are one in 2500 air molecules. The cube root of 2500 is 13.572, so CO2 molecules are about 13 to 14 molecular layers apart from each other at earth’s sea level. They don’t have any idea that they are not alone; they can’t gang up on the EM wave, or photon. So a single CO2 molecule will grab the photon if the photon passes within meters of the molecule; any CO2 molecule.
Barns! I learned something new! (Actually, some other stuff, too: this helps explain why a little CO2 is enough to saturate certain frequencies).
Finally, no one ever answered about the endochronic properties of resublimated thiotimoline…
An interesting alternative point of view is also possible. Logically the same as the currently accepted view
The current viewpoint is in what I call an X space.
Plus infinity to minus infinity in all directions.
How about a 1/x space instead as a viewpoint.
In that case the 1/(c2 v2) term in the conventional view on the RHS becomes instead (c2 v2) on the LHS
That term now lies with Maxwell’s equations rather than Newton’s which does seem more logical
Still the same mathematical outcome though.
Indistinuishable from the cuurrent view by maths or experiment.
A very very different viewpoint That is still logically the same space.
There appears at fist glance no way to prove or disporove this state of affairs.
https://climatedatablog.wordpress.com/2016/01/03/the-duality-of-0-%e2%88%9e/
I’m gonna go with occam’s razor.
You’re all complicating the matter.
So I’m right.
Every time.
Dear Lord, the level of Physics understanding in this discussion is (mostly) so low I am now doubting everything I previously read on WUWT. Last thing I needed.
lucaturin,
Examples, please. Or is everyone else stupid?
Assertions like yours get a low credibility rating here. If you disagree with a particular comment, you get to dispute it if you want to. But if all you do is complain about how “low” everyone else’s underastanding is, how do we know it’s not your own understanding that’s deficient?
I like this one: “Photons are produced at a frequency so as to produce light. Specifically, 5.83 x 10^14 photons per second produce the light we humans perceive as green colored.”
Photon’s have a length (and a shape), antenna’s and lens are designed based on the length, Frequency is time divided by the length of the EM field making up a photon, and I think all photons come from moving “charge”, just as all moving “charge” radiates EM fields, moving an EM fields moves particles with “charge”.
Also photon’s are the force mediator of “charge”, they are why your hand does not pass through a wall.
Almost all human interactions with the physical Universe are based on photon’s interacting with charge, all except those few that are based on the weak force (smoke detectors, radon production from natural uranium) and the less frequent strong force(fission reactors, Sun).
A few low-credibility gems from your own maunderings:
“And I think the photon would effectively be two half photons; actually, they would each be a whole photon at a lower frequency.”
“you wrote that the size of electrons can be measured. But can it be? Electrons exist as probabilities, like photons.”
” If they’re really going that fast, then their mass must be infinite. What am I missing?”
“Really, photons probably think they’re traveling infinitely fast. […]. Or something…
“Specifically, 5.83 x 10^14 photons per second produce the light we humans perceive as green colored.” And if our eye only catches half of them, then we see red.
lucaturin,
My comments are not refuted just because you don’t agree. I gave examples; you gave your opinion. For example, I wrote that a photon would effectively be two half photons, I did not say it was two half photons. I suppose I wasn’t as clear as I could have been. But I added that each would be a whole photon. You conveniently left that part out.
Next, electrons are subject to the same quantum effects in a double slit experiment as photons. You didn’t know that? The experiment is much more recent, and more difficult. But in fact, even atoms obey the same rules.
Next, I neglected momentum in my question of why photons have energy, and thus mass, which explains why they don’t possess infinite mass even going @ur momisugly c.
Finally, my comment on time dilation seems to have flown right over your head at FTL speed. Refute it if you can. But just asserting that it’s “low credibility” without any supporting evidence indicates that you’re the one with no credibility. I admit it when I’m wrong, or if I don’t know something. That’s the difference between us.
So hey, how about that dangerous man-made global warming? Your opinion would fit in perfectly. Betcha think it’s a big problem, huh?
@dbstealey
wrong again: I think _both_ your comments and AGW are complete bollocks.
luca,
If you gave specific reasons, I could respond to them. But your comments are vague as usual.
“Photon’s have a length (and a shape), ” ah but do they have a width and height as well?
How wide is a photon and how do we know
” How wide is a photon and how do we know”
It’s a property of em field as it leaves the emitter at the speed of light and how quickly the polarity of the field as it changes.
So as a percentage of wavelength? Ptate or sphere?
About 9.5 feet is 1 wavelength at 100 mhz.
That’s long isn’t it. How about the other two dimensions?
Depends on the emitter. In the case of a vertical, it propagates the 360 degrees horizontally. Dipole have lobes, phased arrays have lobes that sweep with no moving parts. Some dipoles spiro around each other and whatever shape that is.
SO that must be true for all wavelengths then? How did we measure the width? Or its is just derived from the length? And are you suggesting that polarised light involves some thing rotating. In which plane? It would have top be some sort or rod shape to get the outcomes observed.
” SO that must be true for all wavelengths then? How did we measure the width? Or its is just derived from the length? And are you suggesting that polarised light involves some thing rotating. In which plane? It would have top be some sort or rod shape to get the outcomes observed.”
I’m not sure if I understand both your question or its answer.
If you have a vertical antenna and apply an electronic signal of the proper frequency it will create a standing wave of electrons and emit radio waves (photons) is a 360 direction. Like a bobber on a smooth lake bobbing up and down making ripples in all directions. A cloud of ionized gas, as the electrons jump to a higher level, when it falls back down, it emits a photon, in this case the antennas and randomly oriented, same as a piece of hot glowing metal, the electrons are vibrating in all directions. The radio signal is well polarized, where the other two are not, polarizers then act like a picket fence allow only one direction, one polarity of photon through.
Though QM allows that one polarity of photon to really be made of opposite polarity mixing together with the combination passing through the polarizer.
One of the human scale QM effects, take two polarizers, cross them at 90 degrees blocking light through them, but if you slip a 3rd polarizer at 45 degrees between the 2 at 90 degrees, I think about 25 percent of the light will pass through the 3 layers, because part of the light that will pass through both the front and the back can be the sum of 2 polarities, and a fraction of each align to the middle polarizer, and passes through the what was the 2 outer blocked sheets.
Sorry. I was taking about rotational phase, aka Polarisation. What mechanism and what shape does that imply?
It’s not sensible to speak about the dimensions of a quantum object as if it’s some sort of body or particle. It can only be represented quantum mechanically as a probability distribution (wave function) which evolves in space and time. This is true of photons and electrons. https://www.youtube.com/watch?v=Xmq_FJd1oUQ is the best animation I’ve seen to help visualize the unvisualizable. After years of working in this murky world, you come to appreciate the sentiments of Niels Bohr:
“Anyone who is not shocked by quantum theory has not understood it.”
and Richard Feynman:
“I can safely say that nobody understands quantum mechanics.”
Yes I know. But the facts are that something of a measurable size move from one place to the other. I don’t like ‘magic blue smoke’ form the movement in between
RichardLH :
“Yes I know. But the facts are that something of a measurable size move from one place to the other. I don’t like ‘magic blue smoke’ form the movement in between”
Quantum field theory provides the ‘magic blue smoke’. If you can imagine a well-defined (“measurable size” – according to some criterion) ripple in a field moving from one place to another …
Are background microwave radiation and red-shift linked instead via 90 degree expression of one from the other?