Theories of dark energy and matter...?
I know very little about dark energy and matter. What little i have read seems vaguely similar to Maxwell's theory of "luminiferous aether". Could someone compare and contrast these theories?
- OldPilotLv 77 years agoFavorite Answer
Aether was proposed to provide a medium to propagate electromagnetic radiation. It works well for that. The problem is that for every thing else, it does not work. The physical properties required make no sense. Lorentz developed what we now call the Lorentz Transform to calculate the motion of the aether relative to another Frame of Reference to explain the observed fact that the speed of light is constant for all observers. That means the aether with the photons moves relative to the observer. Now comes the problem: For the aether to do what it does it must have a Modulus of Elasticity greater than steel. Think of standing in a river of very fast flowing water, it explains perfectly the motion of the small floating twigs (photons) moving past you, but why don't you feel the motion of the water (aether)?
This is why Special Relativity replaced Aether. Einstein re-derived the Lorentz Transform showing that it worked just as well if you assumed that space-time (Einstein's Great Insight) could expand and contract based on the relative motion of observers. Einstein resolved the above paradox, so SR replaced aether.
Dark Energy was predicted by Einstein in General Relativity
Observation: The universe is expanding at an accelerating rate. Fact.
General Relativity: If you crank through the equations, IF space was pervaded by a thin "mist" of energy then that energy would create "Repulsive Gravity." ====> Dark Energy is predicted by General Relativity.
History: When Einstein cranked through GR he found that the universe should have collapsed on itself shortly after the Big Bang. Clearly, that was not what happened, so he added just enough Dark Energy (The concept of Dark Energy did not exist at the time, for Einstein it was a true Fudge Factor, but that is what he actually did, add invisible energy to the universe.) to make the universe steady state. At the time it was believed that the universe was steady state neither expanding or contracting. Einstein believed it and added a Fudge Factor he called the Cosmological Constant to make his calculations match what he believed to be true. Then Hubble showed that the universe was expanding. Einstein called the Cosmological Constant his "Biggest Blunder."
Now, years later we find that there is a need for a Cosmological Constant to "fine tune" GR to match what we see in the universe. It is no longer a Fudge Factor but the Energy Density of Dark Energy in our universe. Its value in Planck Units is 1.38 * 10^-122. When the Cosmological Constant is small, gravity causes a universe to collapse on itself. When the Cosmological Constant is large, the Dark Energy causes the universe to blow itself apart. Our universe is blowing itself apart, but it is close enough to the steady state balance density that the process has taken and will take billions of years.
Dark Matter explains why local groups of galaxies orbit each other in tighter orbits than can be explained by the amount of matter we can see. ====> Some matter must be invisible (Dark), possibly large black holes. No one knows for sure though.
- DozoLv 67 years ago
Join the club. We all know very little about dark energy and matter.
Luminiferous aether is a medium to other stuff, expecially electromagnetic radiation. Dark matter shows absolutely no interaction with electromagnetic radiation.
- artzerLv 43 years ago
because there's a finite volume of mass and means contained in the universe, if all of it became switched over to means in a universe increasing swifter and swifter, the universe may finally end up with a lot less and a lot less means per unit volume. this does no longer look like a fashion to commence a sparkling massive bang, it truly is meant to commence with very intense means density and espresso volume. I have an selection theory. the boom is accelerating now, so in case you "run it backwards" you may have a universe shrinking and decelerating because it went. If it became decelerating on the right fee it may by no skill attain 0 length. So thinking the ahead course in that gentle; per chance the universe by no skill had a large bang; per chance it became consistently more suitable than 0 length and increasing. The farther lower back in time the slower the boom. it might want to were lower than one cubic meter in volume, increasing at lower than a millionth of a meter per 2d, and accelerating at a really sluggish fee trillions and trillions of years in the past operating example. yet I have by no skill heard this concept proposed by utilising any professionals so I anticipate the speed of acceleration isn't correct to help that concept.
- 7 years ago
even i do not know but if you are ready to know my theory .i have studied that we cannot see dark matter but its gravitational force can be felt that is felt because the tortion created in space-time but yet we cannot see is because it is not belong to our dimension it is not in reallity because space deos not passes because we see the objects not only because of light because space passes through it but in dark matter there is no space the space just bends and passes away that is light also bends and passes away .....................................