In the Hafele-Keating experiment (cesium clock on an airplane), is it important how the clock is posed, as in 3D xyz pose?
I have found no mention or discussion of the pose of the clock, which should be important, right? Specifically, the path of the cesium beam or the microwave beam inside the clock. Let’s say the airplane velocity is in the +x direction. I would think there is a difference between the cesium beam or microwave beam
- also moving along the x axis,
- or along the y axis, or z axis,
because in the y or z, the beam literally is traversing a longer path to get to the other side (the famous v, sqrt(c^2 - v^2), c right triangle, not in a theoreticalinternalclock way but in a practicaltravelpath way).
Beam path https://cdn.britannica.com/10/99010-004-E79A90B6/atomic-clock.jpg?s=1500x700&q=85
Pose of Mr. Clock https://en.wikipedia.org/wiki/File:Hafele%E2%80%93Keating_experiment.jpg https://en.wikipedia.org/wiki/File:HP_5061A_Cesium_Beam_Frequency_Standard.JPG https://www.youtube.com/watch?v=gdRmCqylsME
According to special relativity, length contraction and time dilation are orthogonal, so to speak. Both length $l$ contraction (along the relative velocity direction) AND time $t$ dilation is observed. Both are simply related through $\gamma$ (the product $l\times t$ is constant), but are otherwise independent. Hence orientation has no bearing on time dilation.
So rotating Mr. Clock in the airplane seat by 90° would have no effect? I don’t understand that given that the actual path of the cesium beam and microwave beam would be different if the beam tube is 90° vs 0° to the airplane velocity.
That is correct, it would have no impact. The time dilation cannot depend on the orientation, for then the time dilation relation $\large t’ = \gamma t$ would not hold as you rotate the clock, and it would further depend on the type of clock! The confusing aspect here is precisely that the transformations occur concurrently, and one is NOT due to the other (though there is a bijection between the two through the $\large \gamma$ factor). One way to “see” this is to sketch the cesium atom beam path in an $\large (x,t)$ Minkowski diagram: the $\large t$ axis is orthogonal to $\large x$ in both frames!
Most (if not all) atomic clocks designed by Hewlett-Packard (hp) have their tubes aligned perpendicular to the front panel (the photo on the right is a more modern clock ~1990, the hp clocks used by Hafele-Keating also used the same internal layout). So the Cs-beams were all pointing in the direction of motion of the plane.
However in the lab, different atomic clocks don’t have their beam all aligned with the eastward direction of motion around the axis of Earth (1180 km/h at 45o latitude). Some clocks have an east-west alignment while others have a north-south alignment (and modern fountain clocks have a vertical alignment). These laboratory clocks are much more accurate than hp clocks, and yet they all remain synchronized. They also remain synchronized with microwave clocks (e.g. hydrogen masers) which also have various orientations.
Therefore, it is known empirically that the paths of the Cs-beam or microwave excitation can be aligned in any direction w.r.t. motion, and the rate of the clock is not affected (now measured with at least 16-digit accuracy).
This is the same type of unintuitive result obtained by Michelson-Morley 84 years earlier - the orientation of their interferometer did not make any difference on the interference fringes.
It is still debated whether it is space and time that stretch, or if it is the matter used to build rulers and clocks that stretches, but independently of which interpretation is favoured, Special Relativity has been empirically tested with a broad variety of experiments and none of them show deviations from theoretical predictions (as explained above by @ftessier).
Interesting discussion, but how can this help us develop an alternative cosmology?
Thanks @ftessier and @marmetl.
> Interesting discussion, but how can this help us develop an alternative cosmology? In an alternative cosmology that replaces Big Bang LCDM, I think we all want
We want absolute velocity and absolute space, therefore we need to examine all the things blocking that.
With respect to the Hafele-Keating and Michelson-Morley setups, I think it is more likely that [there is a nuanced bug in the conclusions from the experiments] than that [one is not allowed to think of absolute velocity and absolute space].
Big Bang cosmology is false and absurd and confusing and has been… shoved down everyone’s throats… and I think it’s not impossible that the head-aching theories on which it is dependent are free from error.
You may “want” absolute velocity and position, but from Galilean invariance to relativistic covariance none of these theories has a need for an absolute position or velocity. Absolute velocity and absolute position cannot be measured, so these concepts don’t seem to have any scientific meaning.
Nobody has found a bug so far, not only for the Hafele-Keating and Michelson-Morley setups, but for the GPS system with atomic clocks orbiting Earth in all directions. Now you might say all these clocks were built by the same American company, so they have the same bug. But the Russian GLONASS and Chinese BeiDou certainly use different atomic clocks design. Yet, despite the much higher accuracy of these navigation systems, none of them have found a different conclusion than that reached by Hafele and Keating.
Relativity might not be 100% correct, but no error has been found to our best measurement accuracy, leaving an uncertainty that is much smaller than what is needed to explain the large observed astrophysical anomalies.
I still maintain that an alternative relativity will not help us for an alternative cosmology because it would have to make predictions that differ from already known tests.
Doesn’t the existence of use of these absolute coordinate systems, https://en.wikipedia.org/wiki/Astronomical_coordinate_systems, make the case?
Another thing… we often see animations and flybys where the camera moves faster than light would in the animation https://www.youtube.com/watch?v=qYNIsgDrIRE https://www.youtube.com/watch?v=08LBltePDZw. Astrophysicists already tacitly model the universe with absolute space and time. These videos are a sequence of frames or images at some absolute position and time state.
It would be great if all of us could only agree upon a Static Euclidean Universe instead of the current one based upon General Relativity .
These coordinate systems are all relative to Earth, for convenience. There’s nothing ‘absolute’ about them.
In the animation, the camera follows ‘Earth’, then ‘Voyager-1’, etc… There is no ‘absolute’ reference frame. The second animation gives a sense of motion relative to the matter we see (galaxies).
Astrophysicists talk about a Hubble flow relative to the CMB, but that is pure theoretical convenience since it cannot be measured. And since the CMB is tied to the matter that produces it, we’re still using a relative coordinate system.
Even in a static Euclidean geometry, the origin of the coordinate system is an arbitrary choice.
I mean absolute as in a piece of length is the same piece of length in any coordinate system, and there isn’t any stretching or squishing.
I’m also saying that shutting down the idea of absolute velocity and absolute position is wrong, because we can continue to define ever-better coordinate systems based on ever-larger centers of mass, and it is not impossible that at some point we find a largest possible center of mass. And it is not impossible that we establish a frame of stillness, such as with the latest measurements of the distant quasars, the Distant Quasar Rest Frame.
@sahil5d .
You may appreciate section 1.2 Mean Rest Frame, in the book Origin of Inertia by Amitabha Ghosh.
@HanDeBruijn Yes. However I currently think the distant quasar dipole is a better candidate than the CMB dipole. https://twitter.com/sahil5d/status/1665862086331875328.
It would be even better if we dismissed the atavistic cultural concept of a Universe as unphysical. The question of whether the Universe is Riemmanian or Euclidean is akin to discussing the number of angels that can dance on the head of a pin - it is a metaphysical argument without scientific meaning. Bud
On Sat, Jul 1, 2023 at 8:35 AM Han de Bruijn @.***> wrote:
Actually no, the geometry can be known by measuring distances and angles.
We measure distances that add up along a certain direction, and the sum of the angles of a triangle is 180 degrees. So the Euclidean geometry is appropriate to describe distances.
Hi Louis,
You missed the point. It is in the context of the simultaneously existing Universe that lies at the base of all modern cosmological systems that the question of which geometry has no meaning. That Universe is falsified under standard physics by the observed scale of the Cosmos and the max light speed limitation. There is not and cannot be such an entity as the simultaneous Universe and therefore discussing its geometry is scientifically meaningless.
As far as observations within the observable Cosmos go, Euclidean geometry does appear quite adequate. The interesting question here is whether this indicates a flat physical spacetime geometry or merely a relational spacetime with no inherent physical characteristics. I don’t think the two cases are distinguishable. Regards,
Bud
On Sat, Jul 1, 2023 at 10:07 AM Louis Marmet @.***> wrote:
Your first paragraph is the metaphysics of cosmology, which is not what my comment was about.
I agree that the two cases you describe in the second paragraphs are indistinguishable. In that case one is free to use either one or the other description. I pick Euclidean geometry because I am more familiar with it.
My original comment dismissed the commonly held concept of a Universe as falsified by standard physics and cosmological observations, and therefore the question of the geometry of the Universe is rendered scientifically meaningless metaphysics.
You objected that you could measure the geometry, although you only implied but did not state “of the Universe”. So what is your point exactly? Is the geometry of the Universe a scientifically meaningful concept or just metaphysics?
@marmetl forgive me if this has been asked before, but what are your thoughts on P. Marmet’s https://www.newtonphysics.on.ca/michelson/?
These two concerns
make a lot of sense to me.
The calculation uses Newtonian physics for light propagating in a medium, mixed with assumptions of ruler/clock dilation, to conclude that Michelson-Morley should not see a fringe shift.
Mixing two incompatible models gives the impression that secondary phenomena have been overlooked. The calculation incorrectly includes some of these effects twice, so although the result “no phase shift of the fringes” is correct, the derivation is not valid. (I’m writing this from memory, I debunked that manuscript ~20 years ago.)
This is false if the angle is measured in the reference frame of the mirror. This is demonstrated by the 4 km-long interferometers used by LIGO which don’t get out of alignment when the Earth rotates by half a turn.
This is known as aberration and is not overlooked by relativity. However, even if light does not enter the instrument exactly at the correct angle, both beams are eventually reflected by the same beam splitter and any small deviation is corrected by the geometry of the instrument to first order in angle.
All that does not change the conclusion that the calculation using special relativity finds that the fringes don’t move, contrary to the claim cited above.
Where in the manuscript?
Not pertinent? The focus here is the angle of reflection of light on a moving mirror in an absolute stillness frame.
An interesting StackExchange question about reflection of light and a moving mirror, https://physics.stackexchange.com/questions/405904/deriving-the-law-of-reflection-for-a-moving-mirror-in-relativity
With the awareness that every mirror is probably moving at v_abs, there may be another way to measure v_abs.
This idea is not focused on path lengths, but on angles.
Maybe this can be tested with laser level surveying equipment with arcsecond precision.
The right-angledness (90.00000deg) of the mirror to the width traveled should be determined mechanically (not optically) with a perfectly chiseled metal block or so, or with a measuring tape (confirm equal length from the startpoint to each end of the mirror).
Scenario 1 I have this picture in my mind of a person holding a laser and pointing it at the mirror. The person and the laser and the mirror is moving at ‘v’. He removes the laser fast enough so that it hits the mirror behind him and the beam continues ad-infinitum. Let’s call this the system
, and there is an observer outside the system at v=0.
We already know that the person sees the light reflecting straight back and froth between the mirrors (90’), but an observer sees the light zig-zag at an angle determined by v, but the beam is always hitting the same point because the moving mirrors are catching up with the lightbeam.
This is not a new picture to us.
Scenario 2 Now there is a way to reproduce the lightbeam from outside of the system; for the observer to point it at the far mirror at a calculated angle to compensate for velocity and a delay to get there, (also momentarily remove the closest mirror to let the beam in and then replace the mirror) so that the beam continues going back and forth between the mirrors.
What will the observer see? The same as before What will the person in the system see? The same as before. The exact same relativity applies, but this is a very different lightbeam, in one space and one ‘c’.
There is no difference to the math of SR here, but this adds a layer of understanding. Here the difference is that lightspeed is determined by absolute space and movement within the space. So what is wrong with saying in scenario 1 the person and the laser has momentum, so his beam is actually going sideways, but since he is travelling at the same v, he doesn’t notice. My argument is that no matter who lets of the light beam, it will travel at the speed that space allows, and there is an absolute limit for everyone!
If the momentum of light argument doesn’t hold, then it means the person at v is holding his laser at an angle.
Here is a test (difficult) that can be done. Let’s make the laser long so we can detect if it is at an angle. Either: Person and observer sees the laser at 90’ to the mirror but the lightbeam zig-zag to the side for the observer. SO the lightbeam is coming out the laser at an angle for the observer so he knows the person is moving. OR: The laser is angled with the beam. The person and observer are both able to detect it. This means the person angles it to compensate for the velocity and he knows he is moving, or the observer knows the other person is moving. ^ Either, OR; Both cannot be true.
Seems to me that if you keep working on reducing the number of assumptions in this line of thought, you might end up with something similar to the Michelson-Morley setup. 😉
@Francois-Zinserling you mentioned “the moving mirrors are catching up with the lightbeam”, which, yes, but the key thing is not that the mirror catches up with the lightbeam, but that the mirror is moving at the time of collision.
This is somewhat like (but not exactly like) Brick Breaker or Breakout https://www.google.com/search?q=brickbreaker+game&tbm=isch where the paddle is moving sideways at collision.
@sahil5d yes I saw that from your earlier link. A disturbing piece indeed. It leaves everything in a rather big mess.
Here’s a criticism of the moving mirror factor from 1922, https://journals.aps.org/pr/abstract/10.1103/PhysRev.19.572. (full pdf, https://scholar.google.com/scholar?hl=en&q=On+Reflection+from+a+Moving+Mirror+and+the+Michelson-Morley+Experiment)
So I looked up Righi… and found https://adsabs.harvard.edu/full/1928ApJ….68..341M, Conference on the Michelson-Morley Experiment Held at Mount Wilson, February, 1927, where his work was discussed. Righi’s analysis makes sense imo. I wonder what ACG thinks.?
“The shorthand notes were taken by Dr. Fritz Zwicky…” 😉
@sahil5d I glanced through the conference notes but it is a big read. The conclusions could not be any different than the current consensus or else we would have known about it.
My earlier comment about the bouncing mirror being a mess was aimed at Einstein’s thought experiment, not at the M&M setup. Einstein’s thought experiment had a light-bouncing-mirro, but no such photon/mirror interactions accounted for as described in that paper you cited.
Another thought I have had; if the movement through the aether was detectable by a mirror setup, we would have heard some noise from LIGO by now. They could not keep a cyclic pattern a secret. So inferemoters won’t do the job.
Even the Saganc effect was refuted as an indicator of aether. Sagnac = SR
One thing I disagree with though - the author (Langevin) claims that the M&M experiment disproved the aether. This is wrong. M&M failed to detect the aether. There is a difference.
In the case of Sagnac, I believe the aether is detected. That SR also explains it, is neither here nor there. SR is extremely succesful in explaining many phenomena, but it is a mathematical abstract tool without a logical (my opinion) reasoning. It’s Ptolemeic in the sense that it provides the correct results but with a dubious premise.
@sahil5d I just read the abstract of the E. H. Kennard and D. E. Richmond paper: (my emphasis) The angle through which a ray is deviated by a moving mirror contains a second-order term in $\frac{v}{c}$, which it was thought by Righi would account for the negative result of this experiment. In this article, the relative ray-paths through the interferometer are traced, the phase difference is calculated and the interference pattern is obtained, and it is found that the second-order term produces only an imperceptible alteration in the fringe pattern. It is concluded, therefore, in agreement with Villey, that the usual interpretation of the experiment in favor of Relativity still holds. that is, Righi made the same mistake 82 years before P. Marmet.
@Francois-Zinserling
Even a small stable Fabry-Perot resonator (two-mirror resonator) would be sufficient to show the effect. We would have heard about it >30 years ago, no LIGO necessary.
I found this old plot that shows the resonance frequency (red dots) of a temperature stabilized F-P resonator (in a vacuum chamber) measured with respect to the reference frequency of a trapped ion (located in the same room). The frequency of the resonator slowly drifts, but does not change by more than 20 kHz in 6 days.
By contrast, the relativistic gamma factor variations for Earth’s speed of 30 km/s around the sun would cause a frequency variation shown by the sinusoidal curve. As the Earth rotates on its axis during a day, this brings the resonator parallel and then perpendicular to the motion of Earth. (The experiment was performed in a lab. at 45 degree latitude with the resonator aligned North-South, the angles are included in the calculation.)
The effect would be much larger than what the measurement shows. It doesn’t disprove aether, but it shows that mirrors/light don’t detect any absolute motion of Earth (if there is such a thing).
@sahil5d I did this measurement in 1998 on the Sr-ion atomic clock, in the context of the same discussion about detecting Earth’s motion. Nothing is detected.
An experiment done over 6 days is not relevant to Earth’s 30km/s. Only the daily rotation velocity range of .5km/s would be relevant. Still, I am interested by the two-mirror resonator experiment. Hmm…
Also, now that we have femtosecond clocks, we could literally measure time of travel. The time of travel for a photon between 2 mirrors, in all 3 axes.
For a 5 meter span between mirrors, given a v_abs of ~ c/1000, the difference in time of travel would be 2 * 5m / c * (1/2 * (1/1000)^2) ~= 17 femtoseconds.
https://www.wolframalpha.com/input?i=2++5meter+%2F+c++%281%2F2+*+%281%2F1000%29%5E2%29
That is if the angle of incidence and angle of reflection are the same. If the photon misses the startpoint, then that means the angle of reflection is different, and that would be interesting as well.
Yes it is. In only six hours the Earth rotates the entire laboratory by 90 degrees. The axis of the 25 cm-long two-mirror resonator starts parallel to $\vec{v}$ at 18h and becomes perpendicular to $\vec{v}$ at midnight. Measurements made on May 12th cover almost 9 hours and probe the relevant $v$ = 30km/s. (The six day time interval is to show that the length of the resonator is stable over time and not changing in the opposite direction of the effect we are trying to measure.)
The 2-axis experiment (parallel and perpendicular to motion at $v$ = 30km/s) has been done and no variation of the two-way travel time is seen that is larger than a fractional change 3 kHz/444 THz = $6.7\times 10^{-12}$. That is, the travel time over 25 cm = 0.83 nanoseconds does not change by more than $6.7\times 10^{-12} \times 0.83$ ns = $5.5\times 10^{-6}$ femtoseconds over 25 cm, orders of magnitude smaller than what you expect to see.
Sorry. I see your point of using 30km/s as a minimum detection target. But if you’re setting a target like that, might as well use our galactic 230 km/s.
Would you have more details on this? Is this something involving a red ~ 700nm photon? Where is the 3 kHz from, and what is the clock?
That would just make the expected signal larger, which would be easier to detect. However I do not know the relative orientation between the resonator and the galactic $\vec{v}$.
A 674 nm laser was used and its frequency $f = nc/l$ referenced to the resonator of length $l = 25$ cm, where the fixed integer $n$ is the number of nodes inside the cavity. If the ‘apparent’ speed of light $c$ changes the frequency will change in the same proportion. The 3 kHz is read on the graph above. On May 12th the frequency did not change by more than 3 kHz.
The reference clock is an ionized Strontium atom that is probed by the same laser, located 3 meters away in the same lab. A description of the experimental setup is given here. I can send you the paper if you really want to read it.
If v_abs is true, I don’t think a frequency change of the photon would necessarily be detectable. This would be a Doppler-like situation inside the two-mirror resonator, where all parts are moving at the same velocity.
A paper I came across A Simple “Classical” Interpretation of Fizeau’s Experiment Giuseppe Antoni, Umberto Bartocci http://www.redshift.vif.com/JournalFiles/V08NO3PDF/V08N3BAR.PDF
on how photon and molecule interactions in an absolute frame yield the coefficient_fresnel. No SR special velocity addition formula needed.
(Also, I think it’s an archaic misnomer to call this “aether drag”. This is just plain photon and molecule interactions in space.)
An interesting read. Nice. I think the aether drag was an attempt to explain the M&M null result by saying earth and air and atmosphere are dragging a chunk of aether with it. It presented its own new problems though, lile how do you drag aether through aether? And if you are dragging aether through aether, are you actually dragging anything?
The water telescope experiment of Airy can also be understood with photon molecule interactions in space. As a photon goes down the tube, the photon goes rightward with each water molecule, and the telescope tilt need not be changed.
Using the time of interaction from the Antoni and Bartocci paper, and water n=1.33 or c_inwater ≈ 3/4 c, and telescope pipe moving right at v, I calculated the photon moves right at 1/4 v.
All in all, the photon is going 3/4 c down, 1/4 v right. So the rightward diff from the telescope is 3/4 v. So the ratio (3/4 v / 3/4 c) is preserved.
By the way, it took me a while to find the original paper and learn that the water in the telescope has its surface parallel to the telescope rim. That’s key to how the photon refraction trajectory at the air water boundary is straight.
Re the explanation of the result of the Michelson-Morley experiment, I might be wrong about the Righi and P. Marmet moving mirror idea. *And wrong about the femtosecond clock time of travel experiment https://github.com/orgs/a-cosmology-group/discussions/82#discussioncomment-6817179.
I now think that [particle shape changing with velocity] (ellipsoid_Heaviside) is the answer. https://github.com/orgs/a-cosmology-group/discussions/138
is just another interpretation of the same behaviour as described by relativity. It has the advantage of not using time dilation and space contraction (which I prefer), but otherwise the theory predicts the same inability to detecting absolute motion.
I disagree. Elsewhere in this discussion I’ve pointed out the ridiculousness of confusing a .98c moving muon and a planetary atmosphere.
Consider a .98c muon hitting the North Pole. And another .98c muon hitting the South Pole. The accurate description is that the atmosphere is close to stationary, and the muons are moving at blistering speed.
@RedshiftDrift why the confused emoji?
On another thread, you had well-articulated a very similar problem.
is wrong. Speed is relative to a choice of any inertial reference, not the reference that weighs the most. One choice is not more accurate than another.
What if the atmosphere weighted only $5\times 10^{16}$ kg, would you agree to pick a muon as reference? What if the atmosphere weighted only $5\times 10^{8}$ kg, would you agree to pick a muon as reference? What if the atmosphere weighted only $4\times 10^{-2}$ kg, would you agree to pick a muon as reference? What if the atmosphere weighted only $3\times 10^{-13}$ kg, would you agree to pick a muon as reference? What if the atmosphere weighted only $2\times 10^{-19}$ kg, would you agree to pick a muon as reference? What if the atmosphere weighted only $1.89\times 10^{-28}$ kg, would you agree to pick a muon as reference?
Where is your cutoff? And why (or why not)?
If some planet had some atmosphere with the masses you have listed above, no, no, no, no, no, no. There isn’t any cutoff, it’s just about describing the situation. The muon (*the result of cosmic protons from outside the solar system!) is moving faster than the planet.
If you see the absurdity (and blatant falsity) of the mathematical transformations of Ptolemaic astronomy and Big Bang cosmology, don’t you see the same with SR? SR is like “all the contents of the universe revolve around every particle”. SR is a Ptolemaic model of the particle.
Can you paint a picture of how you would make sense of cosmic muons colliding with the whole sphere surface of planetary atmosphere by using SR-thinking? What are the attributes of the muon colliding with the South Pole, the muons colliding with the equator? What are the attributes of the Earth, and of the Sun? Is the Sun now moving at .98c to placate SR?
@sahil5d first of all, muons are not cosmic 😕 The correct description of the process is a collision of a cosmic ray with the nucleus of one molecule in the upper atmosphere which creates a pion (and more particles) which then quickly decays into a muon (and other particles). The rest of the atmosphere is irrelevant to the description, except for its thickness of roughly 100 km. The muon travels a distance of 100 km and reaches a detector on the ground (a detector that is in the same frame of reference as the nucleus that produced the muon).
The lifetime of a muon is $2.2 \ \mu s$ before it decays into something else (electron, neutrino, etc.) At a speed $s_\mu$ near the speed of light, the muon would travel an average distance no larger than $d = 2.2 \ \mu s \times s_\mu \simeq 660 \ m$ before decaying, according to Newtonian mechanics. However, detected muons must travel 100 kilometers between the nucleus and the detector, so this Newtonian model for the distance $d$ is inappropriate.
A better picture starts with the lifetime of a muon, which is $2.2 \ \mu s$ as measured with a clock in the same inertial reference frame as the muon. In your language: the lifetime attribute of a muon is $\tau = 2.2 \ \mu s$ as measured with slow muons produced in the laboratory (this is not a Ptolemaic invention). The ~100 km length attribute of the nucleus-detector path is another observable of the system (William Shatner directly experienced the distance to the upper atmosphere, it’s not a Ptolemaic invention). The detected muons also have a large speed $s_\mu$ with respect to the nucleus-detector frame of reference (a pair of detectors are used to measure that, see Fig. 1 here, also not a Ptolemaic invention). Note that speed is not an attribute (forget Blender 😕 ) but a measured relationship between two objects. Now according to SR, the muon’s internal clock is slower in the nucleus-detector frame of reference and its measured lifetime is therefore $\tau_s = \tau / \sqrt{1 - s_\mu^2/c^2}$. That’s how it survives over a distance $d_{SR} = \tau_s \times s_\mu$ reaching 100 km. Note also that the lifetime $\tau_s$ is not an attribute of the muon but instead, like speed, a relative measurement done with a clock that is not in the frame of reference of the muon.
Confusing :confused: is also the false equivalence fallacy of the comparison between my description of mathematical transformations of the Earth’s geometry and the observed muon properties. Since we have observations of the muon-lifetime both before and after the mathematical transformations (Lorentz factor), SR transformations are not of the same nature as the mathematical transformations invented to convert an observed quantity into an imaginary quantity. In the equation above, $\tau_s$, $\tau$, $s_\mu$ and $c$ are all measured. By contrast, the “flat Earth” resulting from a mathematical transformation is never observed, just as for “Ptolemy’s celestial spheres”, “dark matter”, “black holes”, “space expansion”, “dark energy”, etc. which are not observed.
Because only the speed is relevant to the description, the direction of the nucleus-detector axis (north-south, equator, etc.) is irrelevant. The description “Sun moving at 0.98c” confuses 😕 the issues because it implies that velocity would be an attribute of the sun when instead velocity it is always a measured property between two objects. The Earth, sun and the “universe” have no bearing on the observed results and do not modify the picture.
Sorry I rushed that. Cosmic *protons. And then after collision, .98c moving muons.
You have not yet answered the question about describing a situation of muons colliding with all sides of the sphere of a planet. What is happening with the muon with opposite velocity on the other side of the planet? What is happening with the Moon, and the Sun? What is the position and velocity of the Sun when one tries to set 0 velocity at the cosmic-ray-produced muon?
I don’t disagree that the lifetime of the muon is longer when moving at high speed. I disagree with “SR is the reason the muon lifetime is longer at high speed”. Cyclotron measurements already showed that high speed particles have a longer lifetime. The phenomenon should be credited to cyclotronics, not SR.
The description from the point of view of a muon is easily obtained using SR addition of velocities. Say muon1’s motion w.r.t. the detector defines the left direction, then muon2 is going right, and both are moving at 0.98c relative to the detector.
From muon1’s point of view, the detector is moving toward the right at 0.98c, and muon2 is moving toward the right at 0.9998c. Since the Earth, moon and sun are essentially at rest w.r.t. the detector (compared to the speed of light), they all move with the detector toward the right at 0.98c.
I disagree with that statement as well: SR is a model, it doesn’t cause anything - philosophers deal with these sorts of things. Meanwhile physicists use SR to quantitatively calculate the longer lifetime of the moving muon as $\tau_s = \tau / \sqrt{1 - s_\mu^2/c^2}$. From the point of view of muon1, muon2’s lifetime is $109 \ \mu s$.
I think that’s so very wrong, wrong practically, and wrong abstractly. To placate the SR model, the vast quantities of the Earth, Moon, and Sun masses are now moving at near-c speeds?? That’s like the erroneous thinking of Ptolemaic astronomy and Big Bang cosmology, except at the particle scale, which is perhaps why it’s so easy to succumb to. And whaddayaknow it comes along with its own special metric, a special formula that distorts lengths (“obtained using SR addition of velocities”).
This is one reason to drop SR.
A few other reasons are that the
can be understood with electron shape becoming an ellipsoid with velocity (ellipsoid_Heaviside), and the
can be understood with photon and molecule interactions in space.
https://github.com/orgs/a-cosmology-group/discussions/82#discussioncomment-6848105 https://github.com/orgs/a-cosmology-group/discussions/82#discussioncomment-6909354
I emphasize the importance of the Fresnel coefficient being understood with photon-molecule interactions in space (without SR, without the SR velocity formula). When light is going with a water current, for example, the photon literally travels a longer distance in between molecules, and also travels with the molecule during time of interaction. That model yields the Fresnel coefficient.
No, this is not what I wrote. Nothing physical has changed, only the description is different. “The Earth, Moon, and Sun are moving at near- $c$ speeds relative to muon1”.
Compare these two approaches - I use the same wording because they are equivalent:
In both cases, if a paradigm works without a concept (such as “celestial spheres”, “absolute coordinate system”, “space expansion”, “dark matter”, etc.) that concept is not needed.
On the other hand @sahil5d you interpret “space distortion” as a “ellipsoidal distortion”, and “time stretch” as a “clock slowing”. This alternative interpretation is compatible with SR and I don’t have any objection. Note that I actually described the muon’s longer lifetime that way, not as “time dilation”.
@sahil5d you are not using the same constellation of beliefs that I use - we are in distinct Kuhnian paradigms (read this excellent article as a review). “Without some sort of a priori paradigm the mind cannot impose order on sensory experience”, but I am trying to eliminate a priori assumptions that come from my beliefs and keep those that are necessary to explain observations. An “absolute coordinate system” is not needed at the particle scale nor at any other scale.
“But you cannot simply describe the other science as false,” Kuhn said, so as long as we insist on staying in our incommensurable paradigms, this discussion will go nowhere. We both see the other’s position as “the erroneous thinking of Ptolemaic astronomy”!
Another word for ‘absolute’ coordinate system is ‘common’. The purpose is to have a coordinate system common to all objects, instead of a special coordinate system for every particle and a special length-distorting formula for every situation, which is SR.
I understand you said the Earth, Moon, and Sun are moving at near-c speeds relative to muon1, and this is also the case with an absolute coordinate system, but you say one more thing. You have 0 velocity at muon1 and then distort surrounding lengths, and that’s what is full of contradictions.
Not true. Here is a catalog, https://arxiv.org/abs/1109.2681, and they’ve been done on a shoestring budget. They can be improved.
These two words don’t mean the same thing.
“Unfortunately, many experiments are not of high quality, never repeated and mostly both” is not convincing, especially when the more accurate experiments detect no absolute motion.
Do you have answers for the 3 bullet points above?
Take a course in relativity, it will show you how to deal with energy and answer the 3 bullet points. Then read my post again and make sure you understant everything Kuhn said.
That is not a scientific answer. The 3 concerns remain standing.
If SR can’t distinguish a muon moving at .98c from quadrillions of tons of nitrogen molecules moving at .98c, that makes it a failed model. It is an even more severe failure by its requirement of special formulas to distort all surrounding lengths for every particle which is treated as if it’s the center of the universe. SR is a Ptolemaic model of the particle.
I request that you relax your certainty that measuring v_abs is impossible.
Show me an accurate experiment that measures v_abs of Earth.
There is the list of experiments in the de Haan paper above, and they can be improved. What has the most promise imo are
I can comment that the speed of a charge field is the same as the speed of gravity = speed of light. The entire filed of study of electrodynamics and also electro and quantum field theories arose because observation showed all (field) effects happen at the speed of light. Electrostatics and electrodynamics, undisputable - speed of light.
Gravity at speed of light is disputed by some, but I think there is enough evidence for that now. Ethan Siegel may not be my favourite scientist anymore, but he wroter a good article here.
Also - LIGO detected gravitational waves within seconds of Chandra detecting X-Rays from the same source.
@Francois-Zinserling What are practical examples or experiments that show the Liénard–Wiechert retarded potential? From what I’ve researched, the “proofs” of the retarded potential theory are examples of electromagnetic radiation. But [photons] are not [attraction due to charge]. There is a major confusion between [directed pulses of electromagnetic energy] and [electrostatic attraction and repulsion].
For the retarded potential theory of gravity, there is the issue of unstable circular orbits, and then defenders of the theory say “because of damping it’s as if there’s no problem at all”. ?? This reads like a fictitious effect to compensate for another fictitious effect. Also, the Wikipedia page “Speed of gravity” says “The attraction toward an object moving with a steady velocity is towards its instantaneous position with no delay, for both gravity and electric charge.” So even according to the retarded potential theory, the experiment to measure v_abs by creating a charge dipole as a trigger could work.
Re the LIGO experiment, I will reserve my opinion on that until I have clarity on the above. Have you seen Hossenfelder’s and Unzicker’s videos on LIGO? @RedshiftDrift do you think they are right?
Also, Feynman worked on a theory that tried to resolve discrepancies by using a combination of half advanced and half retarded potentials. Maybe we should just go to the obvious solution…
Perhaps those are old, links please.
https://youtu.be/WWTvNlfkvoI?si=1S2OCM2FxMH8OHaQ from 2019
https://youtu.be/y21KWiurLSc?si=wEkeel0CC6gxvgZr from 2022
@sahil5d I do not mean that gravity between objects happen at the speed of light. That idea leads to too many problems, as you also point out. In my opinion this is also why gravity cannot be a ‘pull force’ between masses but must be a ‘push force’ from a medium(aether).
Both for gravity and electrostatics, I think of it as the ‘surrounding field gets updated’ at the speed of light. For gravity this will then also account for some velocity effects like it already does in electrodynamics.
I don’t understand the distinction you’re making. Could you explain? When retarded potential physicists say that gravity moves at the speed of light, what else would they mean but that the surrounding field gets updated at the speed of light?
Also, what is the proof of the Liénard–Wiechert retarded potential? I argued above why I think the usual “proof” is not valid. Photons are not attraction of charged bodies.
Also, what do you think about that line in the Wikipedia page “Speed of gravity” and how even within that framework, the attraction is to instantaneous position, and thus the v_abs experiment with a charge dipole trigger is possible?
@sahil5d I am not sure of your question but I will give it a go.
Maxwell and Newton equations have no time components in them. They work well for static charges and masses, and by each having sufficient time to set up a surrounding (static) field, we can observe effects like ‘instant action at a distance’.
But when things start moving the situation changes. Rapidly so for charges (because of relative strength and also relative velocities of the interactions) but less noticeable for masses. Electrodynamics have done advanced research on this, because it is so easily observable and testable. Not only for velocity but even also for acceleration. Not so much for gravity. We are still stuck with Newton because GR is slow on popping out usable solutions.
Retarded potential considers propagation time from the source to the observer, so it tries to account for the ‘instant action at a distance’ which logically cannot be correct but in gravity still somehow seem to work. Even in the case of gravity sun-to-earth there is an 8 minute retardation. Yet the earth is attracted not to where the sun was 8 minutes ago, but it is attracted to exactly where the sun is NOW. This seems like Newton is correct but we know causally it cannot be.
So the logic conclusion is that there must be a secondary effect based on velocity (lateral - sideways velocity, not radial inward or outward). This velocity component is very well observed in electrodynamics, and this is being logically pushed in gravity. Yes, the velocity component caters exactly for the anomaly, but if there were no velocity there would be no anomaly. So I don’t see a problem with solving it that way.
You are right. Photons are not attraction of charged bodies. Even quantum physics have not solved this yet, not even with virtual particles. The actual mechanism of charge attraction or repulsion is still unknown.
I still don’t get the distinction you said there is between “gravity moves at the speed of light” and “the surrounding field gets updated at the speed of light”. What distinction is there?
Those assertions might not necessarily be true. Anchoring on a belief that “no changes can happen faster than c” might be wrong.
I hypothesize that photons and electrons (informally, “things”) may be able to move from point to point in a volume no faster than c, but acceleration vector changes at all points in the volume could happen, instantly.
That may be possible, sure. A velocity-dependent term might exist in an expression for instantaneous gravitational attraction. But that is not proof of “the surrounding field gets updated at the speed of light”.
The distinction is that we cannot really say gravity moves at the speed of light, because when mass is there, gravity is already there. There is no way to say it isn’t, because if you can see it (light) you can already feel it (gravity). Then it might appear that gravity is instant, but it isn’t.
But by saying the field gets updated at the speed of light, e.g. when a mass moves, we are saying gravity gets updated or ‘changes’ at the speed of light. It all works out fine with ‘c’ as the limiter. So e.g. a gravitational wave is the wave of the changes in gravity. d(gravity)/dx, or d(gravity)/dt depending if you are measuring over distance or over time. Either way, this wave moves at the speed of light. No need for any superluminal speeds or spooky actions.
I still challenge that. There is the issue of unstable circular orbits, which is excused by another effect “damping”. And according to the Wikipedia page on the [gravity field gets updated at c] model, “The attraction toward an object moving with a steady velocity is towards its instantaneous position with no delay, for both gravity and electric charge.” So the entire model could be frivolous!
I disagree. There is a need for a model of [instantaneous gravitational attraction], which is that the [gravity field gets updated at c] model may be unnecessary and wrong, because practically and theoretically, attraction is to instantaneous position. I think we should take a hint from Feynman’s half-retarded and half-advanced theory.
Also, while “superluminal” is a somewhat fair description, it’s not like a thing is moving like a photon is moving. It’s more like an instant state change at all points in the volume. And “spooky”? Well, ok, but it’s happening everywhere, so amend that to spooky action between all distances, or better yet, exceedingly normal action in the whole volume.
> have you seen Hossenfelder’s … video on LIGO?
Wow, she’s so “zen” in that video! I agree with most of what she says. When one looks carefully at “gravitational wave detection” experiments, a lot can be wrong in the interpretation of the signals since many other physical effects can explain similar detections.
The LIGO website explains “LIGO’s sensitivity to gravitational waves will be limited by the quantum nature of light at high frequencies between about 200 Hz and 10,000 Hz and by Brownian motion in the suspensions and test masses at frequencies from 10 Hz ~ 200 Hz.” Therefore only signals at 200 Hz appear with their full amplitude, and any other frequency is necessarily attenuated by the detector. The signal amplitude should therefore peak at 200 Hz and have a smaller amplitude at other frequencies. And that’s exactly what is seen on the data.
I indicated the period of a 200 Hz signal on the figure, right at the frequency of the expected best response of the detector. So a prediction based on the detector response explains the data without any gravitational wave.
Other problems mentioned on Hossenfelder’s blog are also of concerns. Example: “In April this year, LIGO started the third observation run (O3) after an upgrade that increased the detection sensitivity by about 40% over the previous run. Many physicists hoped the new observations would bring clarity with more neutron-star events that have electromagnetic counterparts, but that hasn’t happened.”
Implicit in previous work, see Refs. 12, 13, 14, 19
There is no way to detect an “absolute stillness frame”, all experiments done so far show Galilean invarience. So if a theory predicts something else, it is in disagreement with experiments.
I still think you have not addressed how light reflects differently off a moving mirror.
As @marmetl mentioned before, special relativity is confirmed in our lab practically everyday, so although any revision about Rømer’s measurements is interesting historically, how does it come to bear on relativity itself? In other words, what are you questioning, or what is your hypothesis?
Why is it a big deal, even if it were sheer luck? https://en.wikipedia.org/wiki/R%C3%B8mer%27s_determination_of_the_speed_of_light
*I made a mistake on Rømer Earth-Jupiter-Io measurements. The 22 minutes is not about additional eclipse duration but about additional time from when an eclipse was expected to start.
To be clear,
I’m criticizing the claim that [those phenomena prove there is no absolute stillness frame, and so we all must think that space is stretching and squishing].
I think the muon experiment conveys my point. The extended lifetime of the muon is not because the height of the atmosphere is shrinking! The muon extended lifetime is due to the internalcirculation of the muon being very different when the muon is moving very fast.
I am open to the idea that there could be an absolute rest frame, there is no apriori reason why this is not possible. Yet, the theory of special relativity rests entirely on the idea that physics is equivalent in all inertial frames (the second postulate about the speed of light is superfluous), and this theory up to now has been confirmed experimentally. I for one cannot see how to reconcile this with the notion of an absolute rest frame.
Those are two distinct claims:
For 1) experiments prove neither [there is an absolute stillness frame] nor [there is no absolute stillness frame]. The situation is that there is no need for an absolute stillness frame to explain experimental results. (@ftessier Special Relativity (SR) and General Relativity (GR) are compatible with an absolute inertial frame of reference but have no need for one because the physics is the same in all inertial frames. There is therefore no empirical way to determine which frame of reference is ‘special’.) Therefore, the choice of one or the other is a metaphysical/mathematical decision for which science offers no guidance.
For 2) “stretching and squishing” of space and time is a model among many others. One can also use a model where matter/light changes its properties when it is accelerated (similar to {but not exactly like} the explanation you give for the muon). Hilton Ratcliffe was one of many scientists who discussed that in one of his books (I forget which one…) In principle, both special relativity (SR) and general relativity (GR) can be rewritten so that space and time are not squished and stretched. This is how Einstein initially developed SR, but for GR the equations were getting a bit complicated and the mathematics had already been developed to address the problem with ‘coordinate transformations’. So ‘squishing and stretching’ ‘space and time’ became the convenient way to calculate things. The language to explain ‘coordinate transformations’ mirrors the type of mathematical transformations that are used in SR and GR.
However the language/mathematics does not necessarily reflect the physical process. We have discussed this earlier: using $\sqrt{-1}$ in equations does not mean that $i$ has a physical reality. For SR and GR, ‘coordinate transformations’ are pure mathematical convenience, and as discussed in earlier posts there is currently no experiment that distinguish between [space/time stretching/squishing] and [acceleration-modified physical properties], so the choice of one or the other is again a metaphysical/mathematical decision for which science offers no guidance.
You express my thoughts so much more clearly! Thank you. By “notion of an absolute rest frame”, I meant one that can be distinguished, which then implies that the physics is different in that frame.
Great, we agree on 2).
For 1), I still disagree. For example, there are choices of frames that are wrong, such as trying to center a coordinate system at the muon coming in hot at .98c. Given there are choices that are wrong, and some more wrong than others, we can work the other way. There are more sensible coordinate system centers than others.
Why is it wrong? What is more sensible? What do you mean by
wrongandsensible? I don’t get it.@marmetl. See Wikipedia: an Inertial frame of reference is a sensible notion in Special Relativity but it’s not so easy in General Relativity. Please stop mixing up the two relativity theories! GR hardly bears any resemblance to SR! That’s also the reason why your [ For 2) “stretching and squishing” of space and time ] section doesn’t make much sense to me.
Physicists are still trying to find empirical evidence of an absolute frame of reference. Experiments that are thousands of times more sensitive than Rømer’s, Michelson-Morley’s, Vessot’s, Hafele-Heating’s, etc. have been performed since then (C.f. Michael Tobar, Jun Ye, André Clairon, André Luiten, Peter Wolf, Giorgio Santarelli, etc.) and have produced no detection so far.
Since these modern experiments are all published in the scientific litterature, @sahil5d why do people in this group always go back to the primitive historical experiments made decades and centuries ago?
It’s like trying to build a supersonic airplane from the Wright brothers’ drawings… Or design an email server based on training homing pigeons…
Funny comparisons but not what’s happening here. Also, that kind of criticism is often made by faster-than-light-expanding-space-standard-model cosmology against light fatigue/tired light/photon hubbling cosmology, so I think you’ve seen cases where there really are deep errors.
Here’s my point. There is an unobjectionable stupidity to centering a frame of reference on a muon coming into the atmosphere at .98c. There are frame centers that are worse than others, and therefore there are some better than others. And the best possible frame is 0 position as the center of mass of the system, and 0 speed as the speed at which objects have the least energy.
The center of mass of a muon is centered on the muon and moves with it. Why would that be a “stupid frame of reference”?
(That’s the same question @ftessier is asking above.)
@marmetl @ftessier Because it’s stupid to establish 0 velocity at the muon, and then say the whole atmosphere is moving into it at .98c.
I don’t understand why this is “stupid”. The alternative is writing physical laws that are only valid for you (the observer), but no one else. By the same token, would it not also be “stupid” to pick the Earth frame as the reference, instead of the Sun?
Louis,
I’m in full agreement with everything you’ve said here except this:
“… so the choice of one or the other is again a metaphysical/mathematical decision for which science offers no guidance.”
From a calculational standpoint that is certainly true but from an empirical perspective there is absolutely no evidence supporting the existence of a causally interacting spacetime so science should reject such an interpretation until there is empirical evidence for spacetime ’s existence.
Frameworks and coordinate systems are useful calculational tools but they don’t necessarily describe anything more than relationships. All physical relationships have physical causes but a successful calculation does not necessarily describe the underlying cause. See Ptolemy and the wavefunction of QM.
The fact that physicists are still searching for an absolute frame is indicative of the mathematicist predilection for ignoring repeated negative empirical results while clinging to unnecessary metaphysical/mathematical constructs. The situation begs the question, how many negative results are enough? Why is anyone getting paid to search for things that considerable empirical evidence says are not there? How can science move forward if it’s stuck in a negative feedback loop?
On Thu, Jul 6, 2023, 11:27 Louis Marmet @.***> wrote:
I meant this from a calculational standpoint. Quantitative models make predictions that are verified experimentally.
A quantitative model can be interpreted in numerous ways, “the existence of a causally interacting spacetime” is only one interpretation of many. Empirical tests do not distinguish between different interpretations of the same quantitative model. So I agree with what you wrote.
I have to clarify what I mean by “no result so far”. There are two types of negative results: