Does ether exists?

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  • #1
RoughRoad
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During the 19th century, it was proposed that light travels through vacuum in the presence of a pseudo medium known as ether. But does it really exist? Is there any evidence whether it exists or not?
 

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  • #2
Dale
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No. There is no evidence that it exists.
 
  • #3
jackiefrost
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I've often wondered if String Theorists consider spacetime as an ether of sorts. I guess it's a pretty irrelevant point regardless.
 
  • #4
RoughRoad
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Is there any experimental proof that it doesn't exist?
 
  • #5
Dale
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How would you conduct such an experiment? If you can describe the experiment you are looking for then someone on this site can probably tell you if it has been done.
 
  • #6
DaveC426913
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Is there any experimental proof that it doesn't exist?

The experimental evidence that it doesn't exist is that there is no evidence that it exists. That and the fact that the physics of EM radiation works perfectly fine without it.
 
  • #8
mgb_phys
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Ether certainly exists
Aether on the other hand doesn't
 
  • #9
fluidistic
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Ether certainly exists
Aether on the other hand doesn't

According to wikipedia, Luminiferous aether is also called "ether". Now if you ask me a scientific reference, I run away!
 
  • #10
Nickelodeon
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During the 19th century, it was proposed that light travels through vacuum in the presence of a pseudo medium known as ether. But does it really exist? Is there any evidence whether it exists or not?

The ether doesn't exist but you could be forgiven if you called it dark energy, or the quantum state or perhaps quintessence, not exactly the same but certainly sharing some of the same properties as the 19th century aether.
 
  • #11
cragar
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If an aether existed the planets would not keep orbiting they would slow down.
 
  • #12
jtbell
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not exactly the same but certainly sharing some of the same properties as the 19th century aether.

Which to my mind is like calling a horse a hippopotamus because they share some of the same features. :rolleyes:
 
  • #13
Nickelodeon
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If an aether existed the planets would not keep orbiting they would slow down.

I just wonder why you think so? If there existed an aether, then one of its most significant features was that it was considered massless so no transfer of momentum could contribute to a slow down.
 
  • #14
Nickelodeon
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Which to my mind is like calling a horse a hippopotamus because they share some of the same features. :rolleyes:

'Hippo' means 'river horse' in Greek so not too different really.
 
  • #15
cragar
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I just wonder why you think so? If there existed an aether, then one of its most significant features was that it was considered mass less so no transfer of momentum could contribute to a slow down.

A photon has no mass but it has momentum and it can transfer momentum , like in laser cooling .
 
  • #16
Nickelodeon
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A photon has no mass but it has momentum and it can transfer momentum , like in laser cooling .

The photon has a frequency which is the bit that relates to its momentum (I think that's right). The 19th century aether was considered as not having a frequency . Perhaps Tesla thought it did but in general I think he was an exception.
 
  • #17
cragar
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well doesn't everything have a frequency , and we are talking about something that doesn't even exist.
 
  • #18
Nickelodeon
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well doesn't everything have a frequency , and we are talking about something that doesn't even exist.

No not everything. The field round a magnet for instance. Einstein's 'spacetime continuum' :smile: the non existent aether to name but a few.
 
  • #19
cragar
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so your implying that gravity is continuous and magnetic fields are continuous and not quantized.
 
  • #20
Nickelodeon
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so your implying that gravity is continuous and magnetic fields are continuous and not quantized.

Yes - but to be honest, I'm not really 100% sure about magnetic fields.
 
  • #21
cragar
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Interesting
 
  • #22
physixlover
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No there is no such experiment,its just theoritical hypothesis
 
  • #23
bjacoby
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No. There is no evidence that it exists.

There is evidence that ether exists. One such evidence is that so-called empty space has properties. Even Einstein acknowledged this. His point was not that ether didn't exist but rather that the concept wasn't needed for calculations!

However, without ether, one has some rather severe philosophical conundrums. Maxwell pointed out that there are really only two ways for energy to be transmitted from place to place. One way is kinetically. In other words if I shoot a beam of particles or bullets or baseballs through space, I can transmit energy from place to place. And note that this can occur through totally empty space (except for the projectiles, of course). On the other hand the other way energy is transmitted is by waves! Light, radio, sound, ocean waves all transmit energy from place to place. But Maxwell noted that such transmissions REQUIRE a medium for the waves to propagate in. Modern physics assumes waves propagating with no medium at all. Modern physics assumes that nothing at all can have properties (empty space). None of these assumptions create any kind of logical system. In the old days, the problem was solved with a hypothetical material to transmit wave energy known as "the aether".

But before we get too excited we should note that light, for example from modern experiments does not seem to be a wave at all. Indeed, it doesn't show the properties waves are known to have with respect to several observations such as the time necessary for energy transfer. Detectors easily show individual "photons" that make up a light beam formerly thought to be a wave. And yet statistically if you have LOTS of photons going through slits etc, one finds the statistical patterns obtained are solutions to the wave equation! It's all sort of a large mystery. Thus it is clear that the 19th century idea of light as a wave in the aether is not correct. Now that doesn't eliminate the concept of an ether, but does indeed mean that the old standard versions are in serious need of revision.
 
  • #24
boit
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Michelson/Morley failed to detect aether WIND with their experiment. Failing to find something does not necessarily mean it does not exist. It maybe the equipments used was wrong or they started on a wrong premise, like trying to measure the speed of a rail track. Nonsense!
 
  • #25
boit
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My analogy is simple you may rightly dismiss me as simplistic. Think of a block of dry ice that can somehow sublime slowly at one end cigar like and form slowly at the other end. To an independent observer it will seem that the block of dry ice is moving. Now that is how you, me, your car, airplanes, space crafts, electrons, photons and pretty much everything else moves in aether. For this analogy carbon dioxide is the aether.
 
  • #26
jlknapp505
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This is one of several linked posts:
1. Light exhibits the characteristics of a wave. (There may be other characteristics, but that's not what this post is about.) It has wavelength, frequency, and the velocity/speed of the wave has been measured to a high degree of accuracy.
2. Waves, such as sound waves, are energy disturbances in some sort of medium. There is an equilibrium of some sort within the medium that the wave propagates through. For example, if you consider time as having a very small period, say a nanosecond, water molecules would have infinitesimal motion with respect to each other during that time. When a sound wave passes through this medium, a structured shifting in the relationships of water molecules with each other occurs due to the energy that the wave imparts to the medium. The wave does not consist of water molecules flowing through the medium, but consists of relational shifts; a line of molecules shifts, causing compression in the fields that hold it to some other molecules, extension from others.
This compression-extension propagates through the medium, and this is what we call the "sound wave".
For each medium, there is a natural speed of propagation for each type of wave. Sound can propagate through air, through water, through steel, but at different speeds due to the differences in the type of medium.
I'm working my way up to something; bear with me.
 
  • #27
Dale
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There is evidence that ether exists. One such evidence is that so-called empty space has properties. Even Einstein acknowledged this. His point was not that ether didn't exist but rather that the concept wasn't needed for calculations!
Please identify one experiment that that is inconsistent with ether not existing. If a concept is not needed for calculations of the outcome of any physical experiment then how is that scientifically different from it not existing?

I am sorry bjacoby, but there is no evidence supporting your position. The only way to scientifically assert that there is an aether is to redefine the word "aether" in such a way as to remove from it most of the properties usually associated with the term. Sure, you can do that if the word "aether" is important to you for some reason, but it would not have anything to do with what most people mean when they use the word.
 
  • #28
jlknapp505
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Post 2:
3. Energy that propagates as a wave can carry more or less energy. This energy can be expressed as an increase in amplitude, for example, but it cannot be expressed as an increase in velocity (see #2). If a wave emitter is traveling through the medium that the wave transects, the velocity of the emitter does not add to the velocity of the wave. It also does not decrease the velocity of a wave moving in opposition to the velocity of the emitter.
4. Changes in waves due to motion of the emitter or detector are expressed as changes in wavelength/frequency. Higher frequency/shorter wavelength waves carry more energy than lower frequency/longer wavelength waves.
5. These frequency shifts are called Doppler shifts; Doppler proposed this in the early 1840's, so the phenomena is named for him.
6. Light (EMR) exhibits Doppler shifts. Accepted theory now believes that light can propagate without a medium, although light does show Doppler changes in frequency.
7. I would argue that the presence of Doppler shifting requires a medium; that no such shifting can occur unless there is some natural propagating velocity to the medium that light passes through.
8. The problem with this is that Michelson, Morley, et al attempted to find this medium, then referred to as the Luminiferous Aether. They failed. Failure of their experiments is taken to mean that the "Aether" does not exist. Still, see #7. The problem is to find a "medium" that light passes through.
See next post.
 
  • #29
jlknapp505
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Post 3:
I've set the stage by listing a number of assumptions. Physics, including mathematical descriptions of physical phenomena, begins with assumptions. A chain of logic then extends these assumptions to some conclusion, frequently called a "model". Evidence is then sought to prove or disprove the validity of the model. I've laid out the assumptions so that a reader can examine them to see if they are valid.
I didn't start out thinking about light, although it was always puzzling to me that light, or ElectroMagnetic Radiation (EMR) had all the properties of a wave but did not require a medium. But I was attempting to visualize Einstein's idea of matter "warping" the space/time continuum that surrounded it. From this I concluded that Space (I dropped the "time" part of it, at least for the moment) had to have structure or it could not "warp". So I wondered what the structure of space was. Is there, for example, something out there between the Earth, for example, and the Sun? I concluded that actually, there was something.
There was gravity and there were also numerous particles, charged and uncharged, atomic and subatomic. I began to think of space as a matrix, dense in the region surrounding planets, thin in the space between. These particles, even though of low density, nonetheless relate to each other by charge (attraction/repulsion) and they also participate in the gravitational fields that permeate all known space. The assumption here is that gravity, although relatively weak, is essentially infinite in range. The attraction simply decreases with the square of distance (Newton's inverse square law). So I wondered: does gravity affect light? The answer is yes, postulated by Einstein, confirmed experimentally. There ARE gravitational lenses.
So: if gravity affects light, does not light also affect gravity? Newton's third law requires that it does.
I then visualized the gravity within space as a kind of fluid, fluid in that it is a relationship between all masses, and that the attraction between these masses changes constantly with relative motion of the masses. I concluded that light, as energy, could cause a temporary change (very small; but then, it doesn't have to be big, it just has to exist) in this relationship. This change, propagating through the fields, is the light wave, and the fields might satisfy the requirements to be a "medium" for light.
So there it is. I look forward to your replies.
 
  • #30
DaveC426913
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jlknapp505, you have posted a hypothesis, i.e. you are "supposing" your ideas, and they are merely ideas.

You now need to show experimental evidence that any of it has a basis in reality.

So far, experiments demonstrate that your hypothesis is false.
 
  • #31
DavidSullivan
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No not everything. The field round a magnet for instance. Einstein's 'spacetime continuum' :smile: the non existent aether to name but a few.

Is it wrong to think of the time-space continuum as an "ether" of sorts? If gravity can warp the t-s-c such that the path of light is changed, doesn't that mean it is "something?" And doesn't electric and magnetic fields, with their action-at-a-distance, also tend to imply "something"is carrying the fields since changes in those fields are limited to the speed of light?

Conceptually I think of time-space as a medium, if not an ether per se. While not "correct" it helps me get my head around some of the "odd" concepts in physics.

-David
 
  • #32
jlknapp505
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About experimentation regarding my hypothesis:
If the gravitational or other fields are the medium through which light waves propagate, then there should be observational differences in the velocity of light in regions of space where gravitational fields are different; e. g., different near a strong source of gravity as compared to a weak region of gravitational fields.
The difficulty of proving this is that we live in one of those strong gravitational fields. As we move out into space we might consider repeating Michaelson-Morley or one of the experiments that grew out of their work. It may also be possible to establish something before that point using data from space missions.
Spacecraft follow trajectories that are mostly known, and communicate to Earth through radio waves, which is a form of electromagnetic radiation. These waves should behave essentially the same way that light does.
So: if we could compare the predicted position of a spacecraft with the position indicated by tracking by beacons on the craft, then we might test this hypothesis. Either the predicted point agrees with the point indicated by tracking, or it does not. If not, then the trick would be to determine if the variance is due to some other cause. If no other cause can be found, then it would seem reasonable to consider the hypothesis I've raised. I don't have that data, but it should be available from NASA, or if not, perhaps it can be gained from some future launch. Any variance between predicted and "actual" position, that identified by a tracking beacon, is simply disregarded as unimportant error, at least in my experience. I don't think data from aircraft would be usable; too much likelihood that positional errors are due to variations in atmospheric conditions. A possibility might also exist to compare "skin track" by ground-based radar with "beacon track" from an on-board beacon. Since the radar waves have to travel twice the distance through any hypothesized medium, and the beacon signal only has to travel this distance once, then there should be a variance in the two signals (after corrections in position due to light-speed lag). You would also have to eliminate any possibility of parallax due to locations of the two receivers.
 
  • #33
jlknapp505
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From Dave C: jlknapp505, you have posted a hypothesis, i.e. you are "supposing" your ideas, and they are merely ideas."
Maxwell showed the electromagnetic nature of light; presumably, that means that the electromagnetic fields around charged particles would interact with light. The only thing I hypothesized here is that, as gravity affects light, light also affects gravity. I don't think this is really revolutionary; it's just applying Newton's third law.
However, I'm not aware that anyone has ever consider this or felt that it might be important. So that's the extent of my hypothesis, that the interaction is important, and that it might be used to explain how light can have the characteristics of a wave without a medium as other waves must have.
This idea may seem trivial; but it attacks the view of light as being a constant (in vacuum), and so it throws a major monkey wrench into the gears of relativity and cosmology.
 
  • #34
Vanadium 50
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Is it wrong to think of the time-space continuum as an "ether" of sorts?

That '"ether" of sorts" has properties completely different from the luminiferous aether of the 19th century. It would be like saying a rabbit is a giraffe of sorts. True, if you redefine rabbit and/or giraffe.

About experimentation regarding my hypothesis:

(Emphasis mine) Personal theories are not permitted on PF, except in the Independent Research forum.
 
  • #35
Dale
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7. I would argue that the presence of Doppler shifting requires a medium;
Doppler shifting is completely compatible with SR and does not require a medium.
 

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