Luminiferous Ether And Dark Energy

[mongoman]

I was glancing through some history comments on past physics events.

I came across a paragrapgh describing how Edward Morley and Albert  Michelson found that a long-standing belief in the "luminiferous ether", was false. This "ether" was supposed to be stable, weightless, invisible, etc..  When I read a few paragraphs on the recently discovered "dark energy", I am wondering if perhaps Descartes, Newton and others may not have been so wrong, after all.

What is your take on this?

[Dumbass]

Dark energy is infact another word for the ether. The catch is the fact that people simply call anything unexplainable/unknown as the ether.

It is used for the philosphers platonic world, by Arab alchemists, midevil doctors and even by modern mathematical physicists such as poincare.

Really the ether is what people regard as the fundemental foundation of the world, yet no one has any threads leading to it.

[Eclogite]

In my extensive ignorance I find myself in forced disagreement.

 

The properties that were assigned to the ether of the 19th century are different, in most important details, to the dark energy of today. There are hundreds of people in the world with the same name as me, some of them middling famous, but none of us are the same person.

[CraigD]

Welcome to hypography, mongoman! :) Please feel free to start a topic in the introductions forum to tell us something about yourself.

I was glancing through some history comments on past physics events.

I came across a paragrapgh describing how Edward Morley and Albert Michelson found that a long-standing belief in the "luminiferous ether", was false. This "ether" was supposed to be stable, weightless, invisible, etc.

This is a accurate summary of the results of the 1887 Michelson–Morley experiment.

 

The important aspect of the proposed luminiferous aether’s “stable” trait that the M-M experiment was designed to test is that, like mediums that carry sound waves (such as air), it should be at rest relative to some velocity, perhaps the center of our Milky Way galaxy or the universe. (Note that, until the 1920s, astronomers didn’t understand that the center of our galaxy and the universe were not the same, or that our galaxy was just one of many and the faint, irregular objects in the sky we now recognize as other galaxies were, so Michelson and Morley didn’t worry as much as we do now about what “the center of the universe” means). It was well understood by the 1880s that the speed of sound in a given “sonic aether” medium was constant, and the speed of light appeared to be very nearly constant. It was well understood that both the relative speed and the frequency of sound waves (the Doppler effect) could be used to measure how fast something was moving through the air (although there are much easier ways to do this), and that the frequency of light changed in a similar manner for light sources, so it was reasonable to design an experiment to determine the relative speed of the Earth through the luminiferous aether.

 

While the technical detail of the 1887 and later version of the M-M experiment are complicated, involving interferometry, the essence of the M-M can be understood as simply measured the speed of light from a distant light source – a star – when the Earth moved toward it,then, 6 months later, as it moved away from it. The speed of the Earth’s orbit was well known to be about 30000 m/s, the speed of light about 300000000 m/s, so a “speed of light measurer” that could distinguish 299970000 from 300030000 (about 0.01%), would be sensitive enough for the experiment .

 

Famously, the M-M experiment found no difference in the speed of light measured from the Earth was moving at different speeds, 6 months apart, relative to the rest of the universe.

 

The simple “measure the speed of light” experiment I describe above is actually done many times each time the GPS is used to find a location. If there was a luminiferous aether that did not precisely stay at rest relative to the center of the Earth, GPS devices would not be accurate without calculations to adjust for the Earth and GPS satellites’ motion relative to the luminiferous aether, which they don’t make.

 

 

When I read a few paragraphs on the recently discovered "dark energy", I am wondering if perhaps Descartes, Newton and others may not have been so wrong, after all.

What is your take on this?

The M-M experiment showed that any theory assuming the luminiferous aether exists as something like the “sonic aether” – which Newton believed – is seriously flawed, while theories that include Special Relativity, which Einstein published in 1905, don’t have this flaw.

 

Dark energy is a kind of “placeholder” for the energy necessary to explain why observations show that the rate at which galaxies are moving away from one another – the expansion of the universe – is not, as Newtonian physics calculates, decreasing, but rather increasing. It doesn’t suggest that Special Relativity, or the conclusion of the M-M experiment are wrong, or that there is a luminiferous aether that shares the the characteristic of the “sonic aether” of being at rest relative to something.

 

Dark energy is infact another word for the ether

This isn’t true among scientists and laypeople with adequate modern physics education, Dumbass. Dark energy is not a well-defined concept – as I noted above, it’s more a placeholder term – but appears to be true, in that it’s necessary to explain the increased rate of expansion of the universe. The luminiferous Aether is a well-defined concept, but has been show to be false, by experiments such as the Michelson–Morley.