Dark Matter and Dark Energy

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What do you think about Dark Matter and Dark Energy

Last edited by Joker on 22 Oct 2011, 4:25 pm, edited 1 time in total.

Its dark and mad...?

I think you mean "dark matter" not "dark madder". I think that there's still a chance that the neutralino, the lightest supersymmetric particle, can account for all the dark matter.

As for dark energy, no one really knows what it is. The interesting thing about dark energy is that, in a way, it is predicted by quantum field theory as being all the virtual particles in the vacuum but the amount was predicted to be 127 orders of magnitude larger than the empirically observed value. Before the discover of dark energy, scientists already knew that the amount of vacuum energy predicted by quantum field theory could not possibly be applicable to our universe because the amount is simply too much (this problem is called the vacuum catastrophe), which is why most assumed real amount is zero and the theoretical terms would cancel in beyond the standard model particle physics models, such as supersymmetric models. So, the real mystery of dark energy is why the amount is so small as well as why it is non-zero.

I think that when something doesn't work, the solution is not to say "there must be some invisible set of particles that we can't sense in any way and that doesn't interract with the universe that we know in any way that we can prove"; but more to say "we're most probably wrong, let's rethink this equation".

That is called naive falsification. If we always went by that formula, then newtonian gravity would of been taken to be proven when they discovered the unexplained perturbations in the orbit of Uranus but they did instead was to hypothesize the existence of another planet and they discovered Neptune. One must always rule out more plausible explanations first before falsifying a a theory that's been empirically tested many times before and passed the experimental tests.

Also note that supersymmetry was originally proposed by particle physicists for reasons completely unrelated to dark matter. It was the idea of astronomers and astrophysicists to propose the neutralino as a candidate for dark matter because they looked at already existing theories to explain dark matter. That's why they find neutralinos to be a much more plausible explanation for dark matter than MOND (Modified Newtonian Dynamics), which I think is what you're referring to.

By the way, as far as MOND is concerned, empirical evidence seems to be against it. Among the most devastating evidence against MOND, at least in my opinion, is that:

1. a_0, the supposed universal fundamental constant seems to require different values for different galaxies, where typically the larger galaxies need a different a_0 from the smaller ones (this is like saying that Plank's constant has different value when the laws of quantum mechanics are applied to the hydrogen atom than when they are applied to the uranium atom), and

2. There are known regions of intergalactic space where dark matter has been discovered via gravitational lensing but where no luminous matter is present.

Both of these problems with MOND are more easily explained by the presence of dark matter. The first one can be much better explained by the galaxies having different proportions of dark matter, rather than the galactic rotation curves being the result of a fundamental law of nature like what MOND assumes. The second point appears to be clear evidence of dark matter in the absence of any other kind of matter.

I think science is not quite ready to grasp the concept that the universe is co-created by our collective conscious awareness of it, which amounts to it being imbued with a tremendous amount of conscious and unconscious energy at all times. So they just call it 'dark matter' and 'dark energy' because... um, uh... well we the scientists just aren't ready to admit that we don't really know how to explain what the hell it is!

actually every scientist worth his salt will openly admit he doesnt know what dark matter nor dark energy is.

that is why its interesting

It think that dark energy is just space un-warping itsself.

Earth orbits around the sun because its moving in a straight line around the circular gravity well created by the massive sun.

If the sun were to explode into shrapnel one day the matter that once made up the sun would spread out at high velocity.

The gravity well would get shallower but wider as the mass became disperesed.

This unwarping of space would force the sun shrapnel to spread farther apart -which in turn would create less mass density -which would cause a further flattening out of space- which would...

In short Einstiens warped space concept would create the illusion that the sun's fragments were spreading out into space even faster than the force of the explosion because space itsself would be expanding and carrying the debris with it. The shrapnel moves out to farther locations because of the brute force of the explosion- but the points in space themselves also move farther apart because local space itsself would also be expanding .

On a larger scale that is what happened when all of the matter of the universe exploded in the big bang.

Dark energy is really just einstein's warped space unwarping itsself in the ever disappearing gravity well created by the initial concentration of matter and mass at the start of the big bang.

That is how the planet Neptune was discovered. Anomalous motions of Uranus could be accounted for by a yet unseen planet without giving up Newton's law of gravitation. Adams and Leverrier did just that and told the astronomers just where to point their telescopes. Voila! Neptune!

Unseen things are hypothesized to account for visible effects otherwise unexplained. For example the neutrino. Either the neutrino exists or the conservation of mass-energy does not hold. Physicists postulated the neutrino which is very difficult to detect precisely because it does not interact much with other matter. Eventually this elusive particle was found. In fact three flavors of neutrinos have been discovered.

The next big test is the Higgs Boson. Will the Higgs finally be found? I don't know. Stay tuned.

ruveyn

There's much science can't explain.

Gravity
Magnetism
Dark Energy/Matter
The Perfect Haircut

What else can be added to this list? I know there's more. Science can explain the properties of these things, but human knowledge isn't quite there yet.

I have my own hypothesis on Lambda.

Of items one and two on your list we know a great deal. We know HOW they work. What we don't know is WHY they work as they work. The underlying cause of gravitation and interactions of charge are not known. This does not prevent us from using them and predicting many things about them.

Isaac Newton said of gravitation "hypothese non fingo" - I feign no hypothesis. He could not say why masses behave as though they attract. Nor could Einstein say why mass bends spacetime. He could say how very precisely with his famous field equations.

ruveyn

I find it interesting how some people, who have no understanding of science, attempt to make comments on scientific threads (the comments saying that things don't exist because there is not enough proof or that somehow anything that is true has already been proven beyond the shadow of a doubt, like it is a court house). It so often seems that these individuals comments have little to do with the topic at hand. Often the posts from people who have looked into the topic and have something to contribute to the conversation are far more interesting, whether their stand is pro or con, at least they contribute.

I am interested in dark matter and energy and excited by every new discovery but I think that the biggest issue regarding the exploration and discovery of dark matter and energy is that we do not yet have the tools to investigate thoroughly. Similar to investigating microbiology before the invention of the microscope. In this instance the issue is that nature and our evolution has not equipped us to sense this type of matter and energy so we are starting at scratch trying to find ways to "see" things that have so recently been discovered by mathematical deduction.

Here is a very simple explanation of Dark matter and energy from NASA along with some recent discoveries and experiments at the bottom of the article.
http://science.nasa.gov/astrophysics/fo ... rk-energy/

I can see from the general theme of my posts that I take on an overly optimistic view on science and tend to get frustrated by people who say something can't be real because they either don't know anything about it or they don't believe anything without absolute proof. Sorry if it comes across as irritating, I have been told that it does and that is not my intent.

QFT

the hypothesis i find most interesting is gravity leaking from other universes, that to my understanding hinges on string or m theory, i might be wrong in that its exclusive to these.

From the linked article:

"But when physicists tried to calculate how much energy this would give empty space, the answer came out wrong - wrong by a lot. The number came out 10120 times too big. That's a 1 with 120 zeros after it. It's hard to get an answer that bad. So the mystery continues."

From the article:

More is unknown than is known. We know how much dark energy there is because we know how it affects the Universe's expansion. Other than that, it is a complete mystery.


What is given in the article is anything but an explanation. The cause of the accelerating expansion of the cosmos is as much a "mystery" as is gravitation. In short, we don't know why., We only know that. Hypothesis non fingo as Newton said about gravitation.

ruveyn

I hope nobody here is going to insinst on dark energy being *real*.
There are quite a few alternative theories but, unfortunately, not that exotic.
For instance: http://www.lifeslittlemysteries.com/acc ... sion-2048/