Celestia Forums

Is mass/energy a dimension?

could dark energy be the centrifugal force of our universe revolving around an axis in the 4th(5th?) dimension?

does anything have have mass/energy = 0?

if plank length is the smallest possible theoretical length is there a largest possible theoretical length?

Random answer: bees are yellow.

yamo wrote:Is mass/energy a dimension?

could dark energy be the centrifugal force of our universe revolving around an axis in the 4th(5th?) dimension?

does anything have have mass/energy = 0?

if plank length is the smallest possible theoretical length is there a largest possible theoretical length?

I don't know about your general knowledge in physics.

You may remember that in classical physics, the kinetic energy is

E_kin = 1/2 * mass * velocity ^2

hence obviously
[mass/energy] = [1/velocity^2]

i.e of course NOT dimensionless. however elementary particle physicists( like myself) ALWAYS work in units where the Planck constant [tex]\bar{h}[/tex] = speed of light c = 1. In such units mass/energy has no dimension! But that's only in a special scheme!

More generally and more exactly is to quote mass in units [Mev/c^2] while energy has dimensions [MeV]. MeV = Mega electron Volts.

Certainly, photons, the quanta of light are massless but can be VERY energetic!
Here the ratio mass/energy is clearly = 0
There are other massless "friends" of the photon, like the gluons where the same is true.

As to your other speculations, many things are possible before they are worked out to some detail . While possible, many speculations are horribly UGLY, like your idea of a distinguished rotation axis of the Universe in some higher dimension. Why should there be a distinguished axis of rotation??

The first question you have to answer then is why experimentally dark energy appears completely "scalar", ie without any spacial inhomogeneity of the associated force. A centrifugal type of force would NOT be of that kind...

Fridger

Revolutions in 4D or higher space do not take place about an axis. Nor in fact do rotations in 2D.

Rotations in n dimensional space take place about an n-2 dimensional region of that space which contains the points which are unaffected by the rotation:

• In 2D, rotation takes place about a point (0D)
• In 3D, rotation takes place about a line (1D)
• In 4D, rotation takes place about a plane (2D)
• ...etc...

ajtribick wrote:Revolutions in 4D or higher space do not take place about an axis. Nor in fact do rotations in 2D.

Rotations in n dimensional space take place about an n-2 dimensional region of that space which contains the points which are unaffected by the rotation:

• In 2D, rotation takes place about a point (0D)
• In 3D, rotation takes place about a line (1D)
• In 4D, rotation takes place about a plane (2D)
• ...etc...

Of course I am aware of this . I chose the word "axis" to make the point of the argument more intuitive to a non-expert. Axis just meaning the set of fixed points under rotation whatever it's dimension. The "non-covariance" of such a concept remains, no matter how the invariant subspace is designated!

Fridger

Incidentally, there is a variety of sensible proposals for dark energy within the framework of gauge theories (in higher dimensions!). What is the REAL challenge about dark energy is the tiny size of it's associated scale! It does not fit into any of the gauge theories of forces we know. In each case, the mismatch is HUGE.

Fridger

t00fri wrote:Of course I am aware of this . I chose the word "axis" to make the point of the argument more intuitive to a non-expert. Axis just meaning the set of fixed points under rotation whatever it's dimension. The "non-covariance" of such a concept remains, no matter how the invariant subspace is designated!

Indeed, however given the nature of some of the questions in the first post, I thought it would be a good idea to clarify the matter.

oops..my fault.. i did not mean mass divided by energy(as i wrote) but ...mass-energy...can a thing have both mass and energy of 0 ...both 0

Those are all Very good questions, and absolutly none of them can be answered completely without using some theory. Hence you will not get a definite answer. I can answer some of your questions based on that theory but if you don't subscribe to that particular train of thought then anything I say will be without meaning. I will try to answer your questions through multiple theories but my field is in quantum energy transferance.

1.)Is mass/energy a dimension?

This is a very debatable question. Whether or not you believe in multiple dimensions plays a big part. Some believe for instance that electrons move in and out of our dimension into others. Some also believe that energy exists on a plane next to ours but not completely intertwined with ours and that is why there is "energy loss", (not loss in heat or light) but we can still utilize it. Others believe that there is just our dimension and no others and that electrons can "teleport".

2.)Could dark energy be the centrifugal force of our universe revolving around an axis in the 4th(5th?) dimension?

That all depends on what you think dark energy is. There is absolutely no evidence whatsoever to prove that dark energy even exists. I do know that there are "unseen" energies all around us and there has to be for alot of our calculations to even work. We even get into the habit of just figuring that into our models. I personally don't subscribe to the dark energy theory and lean more towards the aether theory. Some say that they are the same, some don't.(i can explain more on the aether theory if you want to know)

3.)Does anything have have mass/energy = 0?

I personally believe that absolutely everything has an energy constant, but not everything has to have mass. So to answer you question, no. I could definitely be wrong as everything is still theoretical.

4.) If plank length is the smallest possible theoretical length is there a largest possible theoretical length?

I really don't agree that plank length is the smallest length nor do I believe that there is a "largest length"

To sum everything up these are all very excellent questions that need to be asked but we simply don't know enough about anything whatsoever to definitively answer any of them. You can ask a thousand of our brightest minds these questions and you will get all kinds of answers. Even basic physics only works "most of the time". If you want a question that will put things into perspective about how little we know and still need to learn. "What is an electron?" We think that we have things covered in that area because we can manipulate them into performing an extremely wide array of tasks but no one on earth can tell you what an electron actually is or even why it behaves the way it does. Once we can actually figure things like that out then everything else will start to fall into place, but until that day you can bet that there is absolutely no definite and that everything is theory.

half0,

Unfortunately, many of your "many believe" answers correspond what is usually known as "voodoo science" -- bogus information promulgated by people who understand English but not math. They've misinterpreted "popular science" articles (which themselves usually have to be taken with a grain of salt) and then they've used their own imaginations while extrapolating what they think they've read into areas that they know nothing about.

The Celestia forum really is not the place to ask subtle physics questions. There are only a few people here with the background to answer them and most of those do not have the patience to respond in the detail needed by those unfamiliar with the topics.

Yamo and others,

I strongly urge that such questions be directed to the "Bad Astronomy and Universe Today" forum at http://www.bautforum.com/questions-answers/
There are many knowledgeable people there who will be delighted to answer even the most confusing questions.

Sorry, but i have to lock this thread.
I do not want it to get into a shouting match, which has happened too often in similar situations.