Starship Asterisk*

by **dougettinger** » Fri Jan 28, 2011 3:39 pm

Gravity is holding Dark Matter and regular matter together. Dark Energy is expelling gravity's influence by expanding the spaces between matter on a large scale (between galaxies) and possibly on smaller scales (such as between the stars).

Doug Ettinger
Low Ranking Science Officer

by **The Code** » Fri Jan 28, 2011 12:41 am

Chris Peterson wrote:One major view of dark energy is that it uniformly fills space in this way (at an extremely low density). The other view is that while its density is uniform on a large scale, it is locally distributed. If the second view is correct, there may be no dark energy at all in the space within atoms, for example.

I think it is a mistake to "believe" either of these. Both are valid ideas, subject to test, but not yet tested. Either may turn out to be correct, or given how little is known about dark energy, neither. This is a good time to keep an open mind and wait for more data.

Firstly, I must say, what an excellent thread. Thanks guys.

Secondly, I see a comparison. The distribution of Matter in the observable Universe, And the observable phenomena seen in the Orion nebula. Why do I see this comparison ?

Thirdly, Does Gravity expel, Dark Energy ? Or is there more to think about ?

tc

by **Chris Peterson** » Wed Jan 19, 2011 4:05 pm

dougettinger wrote:What kind of calculations based on the WMAP data are used.

As I understand, it has to do with the different scales of observed structure, which imply critical wavelengths early in the Universe. You'd have to go to primary sources for details, it's not something I've ever looked closely at.

I believe that space, or the voids between matter, or hard vaccuum, or the separations between galaxies, or whatever you wish to call it - is filled with energy.

One major view of dark energy is that it uniformly fills space in this way (at an extremely low density). The other view is that while its density is uniform on a large scale, it is locally distributed. If the second view is correct, there may be no dark energy at all in the space within atoms, for example.

I think it is a mistake to "believe" either of these. Both are valid ideas, subject to test, but not yet tested. Either may turn out to be correct, or given how little is known about dark energy, neither. This is a good time to keep an open mind and wait for more data.

by **dougettinger** » Wed Jan 19, 2011 2:33 pm

What kind of calculations based on the WMAP data are used. Are the volumes or areas of the voids between matter calculated and determined to be a percentage of all energy ? ?

I believe that space, or the voids between matter, or hard vaccuum, or the separations between galaxies, or whatever you wish to call it - is filled with energy. One can divide space from our pespective three ways. There is the space inside each and every hadron, atom and molecule; there is space between the stars and planets; and finally the incomprehensible space between galaxies. At the first level there are the photons, bosons and gluons permeating space that create energy. At the second level photons, neutrinos, and isolated electrons permeate space. At the third level space contains the second level items including the dominating Dark Energy. If conglomerations of matter move away from each other they gain potential energy. The Big Bang(s) cannot be envisioned without the dark void having energy. This is how see the connection between energy, matter, and space.

Doug Ettinger
Pittsburgh, PA
01/18/2011

by **Chris Peterson** » Tue Jan 18, 2011 11:01 pm

dougettinger wrote:So how do cosmologists compute the percentages of Dark Energy being 72% and Dark Matter & regular matter as 28%?

The most accurate numbers come from calculations based on the WMAP data for the CMB. Less accurate numbers, but very consistent with the WMAP analysis, come from looking at the large scale structure of the Universe, that is, how matter clumps. This produces an estimate for matter of about 30%, leaving dark energy to account for the rest of the total energy budget.

The idea that Dark Energy pervades all of expanding space is unavoidable.

I don't know that it is unavoidable, but that is certainly consistent with current theory. The exact nature of dark energy, however, would determine if it is uniformly distributed or not.

by **dougettinger** » Tue Jan 18, 2011 10:06 pm

So how do cosmologists compute the percentages of Dark Energy being 72% and Dark Matter & regular matter as 28% ? In this case obviously matter and energy are equivalent. I know how the percentages of Dark Matter and regular matter are computed.
The idea that Dark Energy pervades all of expanding space is unavoidable.

Doug Ettinger

by **Chris Peterson** » Tue Jan 18, 2011 8:19 pm

dougettinger wrote:The explanation for space expanding at an increasing rate is Dark Energy. So what is the connection then between space and energy ? Is Dark Energy a misnomer ?

The fact that space and matter/energy can interact does not mean they are the same thing, or that there is any fuzzy area between them.

by **dougettinger** » Tue Jan 18, 2011 8:08 pm

The explanation for space expanding at an increasing rate is Dark Energy. So what is the connection then between space and energy ? Is Dark Energy a misnomer ?

Doug Ettinger
Pittsburgh, PA

by **Chris Peterson** » Tue Jan 18, 2011 7:53 pm

dougettinger wrote:Depending on our perspective the dividing lines between space, energy, and matter are very fuzzy.

I disagree. Energy and matter are the same thing, and you could make a case that there are states where it might be a bit ambiguous which term best applied. But space is not matter/energy, and there is no confusion between space and matter/energy.

by **dougettinger** » Tue Jan 18, 2011 7:31 pm

I mis-stated that "only galaxies expand". I really meant that the space between galaxies expands. And yes, matter does not expand. I am only toying with that idea of matter expanding. Most of matter is space itself and those particles in that space making up matter could be converted to energy. Depending on our perspective the dividing lines between space, energy, and matter are very fuzzy.

Doug Ettinger
Pittsburgh, PA

by **Chris Peterson** » Tue Jan 18, 2011 4:05 pm

dougettinger wrote:I am trying to enhance your balloon analogy. The 3D surface that you refer to can be considered as the skin of the balloon that has a thickness of the "observable" universe. If not for gravity, all matter inside this 3D surface would be expanding uniformly. We do not know the age of the overall universe; we only speculate the age of the "observable" universe. Is this a further enhancement ?

No. The surface has no thickness. The observable universe is a region on the surface (not in it) around each observer. Gravity is the force that holds things together within small regions- essentially, causing them to slide on the surface as it expands, rather than staying with that surface. We do know the age of the overall universe, because our observations of the observable universe tell us that.

I now add another thought experiment only for your enjoyment. Your balloon analogy is an excellent way to explain how each and every bundle of matter expands in a similar fashion - such as stars, planets, and our own bodies. I believe that our thinking is still very self-centered in believing that only galaxies expand in this manner.

Each and every "bundle of matter" does not expand. Galaxies don't expand, either, nor even galaxy clusters. Dark energy (which again, is not driving expansion) does not work over these relatively small scales.

To put it a little differently, matter does not expand. The Universe itself is what is expanding, and matter is carried along or not, depending on the degree to which it is bound gravitationally to other matter.

by **dougettinger** » Tue Jan 18, 2011 3:50 pm

Chris Peterson wrote:Let's go back to the balloon analogy. The universe is the surface of the balloon, so this is a 2D universe we are considering. You can stick little dots all over the surface to represent galaxies. As the balloon expands, these galaxies are getting farther apart. But are they moving? You could argue that they are not. If you were perched on one of those dots, you'd feel no forces in the plane of your universe. No acceleration, even if the expansion rate was not uniform. Of course, from our vantage point we understand that you'd feel a force in what we'd call the vertical or radial direction... but that direction isn't accessible to those living on the balloon, because they only perceive two dimensions. And if you look at what direction the dots are actually traveling, it isn't a direction along the surface, but is in a straight line away from the center of the balloon- a point that isn't even in that spatial universe.

Now, if you can, extend the analogy to our own Universe. We inhabit the 3D surface of a 4D universe. Distant objects aren't really moving with respect to each other (except in a minor, non-cosmological way). What's happening is that the Universe is expanding, and all these essentially stationary objects are staying in place. The only direction anything is moving is away from the 4D center of the Universe- the point where t=0. We are moving on the radial (time) axis of the Universe. We don't feel any forces on this axis. We can't see along this axis ("outward", the direction we are expanding, is the future; "inward", the direction we came from, is the past).

So, from the instant of the Big Bang to now, nothing is moving very much, nothing was propelled, nothing felt any forces from the BB.

I am trying to enhance your balloon analogy. The 3D surface that you refer to can be considered as the skin of the balloon that has a thickness of the "observable" universe. If not for gravity, all matter inside this 3D surface would be expanding uniformly. We do not know the age of the overall universe; we only speculate the age of the "observable" universe. Is this a further enhancement ?

I now add another thought experiment only for your enjoyment. Your balloon analogy is an excellent way to explain how each and every bundle of matter expands in a similar fashion - such as stars, planets, and our own bodies. I believe that our thinking is still very self-centered in believing that only galaxies expand in this manner. Each bundle of matter is increasing its entropy to return to the void of Dark Energy. The properties of light help to collaborate this belief.

Doug Ettinger
Pittsburgh, PA
01/18/11

by **Beyond** » Fri Jan 14, 2011 6:11 pm

Chris Peterson wrote:So, from the instant of the Big Bang to now, nothing is moving very much, nothing was propelled, nothing felt any forces from the Big Bang.

So the things of this realm that we can see, to way out in the vastness of space, are being carried along by "something" that we can't see, but can tell It's there, because of the constantly growing distances between the things that we can see. And the farther we are carried along, the faster the distances between things grow. So scientists are trying to find out just what this "expansion" stuff really is. Whether it is common to this realm that our Universe is in, or if perhaps it came from another realm that might have "leaked". Either way i don't think there's a darn thing that anyone now here could do about it, but it may be nice to know what the heck this expansive stuff really is. For all we know, it could be an unseen hand from "somewhere", taking SpaceShip Universe to a better place.

by **rstevenson** » Fri Jan 14, 2011 3:26 pm

Yes, much more complete than mine. I'll try to remember the balloon analogy that way.

Rob

by **owlice** » Fri Jan 14, 2011 1:25 pm

Chris, great explanation; thank you.

by **Chris Peterson** » Fri Jan 14, 2011 12:38 am

dougettinger wrote:
dougettinger wrote:Thanks for the reply. You do bring forth another question. You state that matter itself was not propelled anywhere by the Big Bang. I always thought that during the epoch when enough cooling occurred that plasma was formed and then finally atoms. Would not these atoms be mattter that is being propelled outwardly in all directions ? Maybe I really do not understand the Big Bang.
I am anxiously awaiting some hopefully easy answer to the above question which has not arrrived yet. Perhaps Chris Peterson could answer this concern. Thanks.

Let's go back to the balloon analogy. The universe is the surface of the balloon, so this is a 2D universe we are considering. You can stick little dots all over the surface to represent galaxies. As the balloon expands, these galaxies are getting farther apart. But are they moving? You could argue that they are not. If you were perched on one of those dots, you'd feel no forces in the plane of your universe. No acceleration, even if the expansion rate was not uniform. Of course, from our vantage point we understand that you'd feel a force in what we'd call the vertical or radial direction... but that direction isn't accessible to those living on the balloon, because they only perceive two dimensions. And if you look at what direction the dots are actually traveling, it isn't a direction along the surface, but is in a straight line away from the center of the balloon- a point that isn't even in that spatial universe.

Now, if you can, extend the analogy to our own Universe. We inhabit the 3D surface of a 4D universe. Distant objects aren't really moving with respect to each other (except in a minor, non-cosmological way). What's happening is that the Universe is expanding, and all these essentially stationary objects are staying in place. The only direction anything is moving is away from the 4D center of the Universe- the point where t=0. We are moving on the radial (time) axis of the Universe. We don't feel any forces on this axis. We can't see along this axis ("outward", the direction we are expanding, is the future; "inward", the direction we came from, is the past).

So, from the instant of the Big Bang to now, nothing is moving very much, nothing was propelled, nothing felt any forces from the BB.

by **dougettinger** » Thu Jan 13, 2011 9:29 pm

dougettinger wrote:Thanks for the reply. You do bring forth another question. You state that matter itself was not propelled anywhere by the Big Bang. I always thought that during the epoch when enough cooling occurred that plasma was formed and then finally atoms. Would not these atoms be mattter that is being propelled outwardly in all directions ? Maybe I really do not understand the Big Bang.

I am anxiously awaiting some hopefully easy answer to the above question which has not arrrived yet. Perhaps Chris Peterson could answer this concern. Thanks.

Yes, you are correct. Dark Energy is required to address the increasing rate of expansion of interglaxalar space. And if photons or their velocity "c" is accelerating by a very small undectable amount ever since the inflationary period of the Big Bang then there would be a reason for the increasing rate of expansion of space.

Regarding a photon beginning its existence at the velocity of "c": I have a difficult time envisioning anything that does not start at rest when it is created unless it is starting from a moving object. I need some help making the jump from Newtonian to Quantum Mechanics.

Doug Ettinger
Pittsburgh, PA

by **Céline Richard** » Thu Jan 13, 2011 7:57 pm

Chris Peterson wrote:I believe that the most popular current viewpoint is that after the inflationary period, the rate of expansion was decreasing, because gravity dominated dark energy. But once the Universe became sufficiently large, dark energy became the dominant "force", and the rate of expansion began to increase- a trend that will presumably continue forever.

That's very interesting.

Chris Peterson wrote:
Céline wrote:Do scientist have any idea about where do black energy come from ?
It is a property of the Universe. It may not be meaningful to ask where it came from (or at least, no scientific answer may be possible).

Yes, it is a property of the Universe. I am sorry to have expressed myself in a confuse way. To express better what i mean, maybe it would be good to make a comparison. A force happens because there is gravitation (involving bodies with different masses), or magnetism (involving electrically charged particles), for example. When a force occurs thanks to black energy, my new question is: does it mean black energy is like a fundamental interaction? Or is it more something, a kind of "body"? If it is like a fundamental interaction, maybe black energy could be related to a new theory, in the future. If it is just something, a kind of "body", perhaps we could seek how it has formed in the Universe (by wondering if it is a basic component, like atoms, or not, for example).

Céline

by **Chris Peterson** » Thu Jan 13, 2011 7:13 pm

Céline Richard wrote:So the rate the Universe is speeding up...

The rate of expansion of the Universe is speeding up.

How can it be possible: is it the consequence of any theory, or is it just an observation we still don't know how to explain? Is it new for the Universe, or has the Universe always been expanding while speeding up?

The apparent increase in expansion rate is an observation. With that observation came the need to provide an explanation, which dark energy does. In addition, dark energy fits into other parts of cosmological theory, as well. The expansion history of the Universe is complex, as it behaved curiously at the very beginning. The actual rate of expansion is determined by different things: the "inertia" of the original expansion and the inflationary expansion, gravitational attraction, dark energy repulsion, and maybe more. I believe that the most popular current viewpoint is that after the inflationary period, the rate of expansion was decreasing, because gravity dominated dark energy. But once the Universe became sufficiently large, dark energy became the dominant "force", and the rate of expansion began to increase- a trend that will presumably continue forever.

Do scientist have any idea about where do black energy come from ?

It is a property of the Universe. It may not be meaningful to ask where it came from (or at least, no scientific answer may be possible).

by **Céline Richard** » Thu Jan 13, 2011 6:57 pm

Chris Peterson wrote: Dark energy is not required to explain the expansion of the Universe. That was understood for a long time without any need to invoke dark energy. What changed was that there was a new observation: the rate the Universe is expanding is not constant or slowing, as expected, but is speeding up. It is that speeding up that requires dark energy, or something that behaves like it.

So the rate the Universe is speeding up... How can it be possible: is it the consequence of any theory, or is it just an observation we still don't know how to explain? Is it new for the Universe, or has the Universe always been expanding while speeding up?
Do scientist have any idea about where do black energy come from ?

Céline

by **Chris Peterson** » Thu Jan 13, 2011 4:09 pm

dougettinger wrote:I am not questioning that the speed of light remains the same and is proven by many well designed experiments. But no one yet knows if the speed of light is different beyond our "observable" universe.

There is nothing special about the observable Universe. It is simply a region of the Universe defined by expansion: anything outside it has simple reached a velocity greater than c with respect to us, and is therefore not capable of interacting with us anymore. Every point in the Universe has its own such observable sphere. There seems to be no reason to think that ours is somehow special, and that physical laws (or constants) are different outside it.

Dark Energy is needed to explain the expanding universe.

You are misunderstanding dark energy. It is not required to explain the expansion of the Universe. That was understood for a long time without any need to invoke dark energy. What changed was that there was a new observation: the rate the Universe is expanding is not constant or slowing, as expected, but is speeding up. It is that speeding up that requires dark energy, or something that behaves like it. Of course, it is still possible (although increasingly less likely) that the observation of increasing expansion rate is incorrect. But since dark energy fills in other holes in earlier theory, it is probably here to stay.

Again as I have already mentioned, I am trying to answer for myself why a photon comes into existence at the velocity of "c". It is usually dismissed at being the way of nature.

Ask yourself why a photon should not do this. It's an equally valid question.

by **dougettinger** » Thu Jan 13, 2011 3:31 pm

I am not questioning that the speed of light remains the same and is proven by many well designed experiments. But no one yet knows if the speed of light is different beyond our "observable" universe. We can only think of such velocities. The "neck of the woods" I refer to is the "observable" universe. Dark Energy is needed to explain the expanding universe. I am just performing a "thought experiment". If the speed of light was accelerating by only a few angstrom units per year, it could not be detected within the limits of error of experiments that have been performed to date. But the thought of it accelerating could be a possible answer for Dark Energy. Again as I have already mentioned, I am trying to answer for myself why a photon comes into existence at the velocity of "c". It is usually dismissed at being the way of nature.

It is your choice to participate or not participate in this "thought experiment". I try to remain humble and bow to any dogma found in current science, But, of course, my brain keeps working.

Doug Ettinger
Pittsbugh, PA

by **The Code** » Thu Jan 13, 2011 1:36 am

dougettinger wrote:Can several different frames of motion be represented mathematically inside multiple overall encompassing frames of reference ? Venn diagramming might apply, but I do not know this. I am simply trying to explain for myself why light might come into existence at the velocity of "c" in our "neck of the woods". It might help explain Dark Energy, too.

186 thousand miles per second, "c" is universal, not our "neck of the woods" How would it explain Dark Energy?

Explaining why Light Speed "c" is set at 186 thousand miles per second, is another story. Yet untold. Huh?
It does not Matter how many times you over lay, or take away, The Speed of light remains the same.

tc

by **dougettinger** » Wed Jan 12, 2011 4:41 pm

Thanks for the reply. You do bring forth another question. You state that matter itself was not propelled anywhere by the Big Bang. I always thought that during the epoch when enough cooling occurred that plasma was formed and then finally atoms. Would not these atoms be mattter that is being propelled outwardly in all directions ? Maybe I really do not understand the Big Bang.

Returning to my idea: You stated that if there is uniform motion of matter then no motion would be observed at all. In local space that would be correct. However, observing the galaxy redshift could be proof of this uniform motion because of the large expanses of time and distance. Just say that the Earth, Sun and other solar system bodies are expanding at "c" as well as their spatial distances, then we as humans would not observe this motion. But since matter has conglomerated over the eons, the relative motions between conglomerations can be observed by mankind because of the much smaller relative velocities. And this would, of course, apply to moving conglomerations of matter on the surface of Earth.

Can several different frames of motion be represented mathematically inside multiple overall encompassing frames of reference ? Venn diagramming might apply, but I do not know this. I am simply trying to explain for myself why light might come into existence at the velocity of "c" in our "neck of the woods". It might help explain Dark Energy, too.

Doug Ettinger
01/12/2011

by **Chris Peterson** » Wed Jan 12, 2011 5:07 am

dougettinger wrote:I found your quote very intriguing. "A photon comes into existence with the velocity of "c". I just like to think outside the box when it strikes me. Just suppose all matter is expanding as witnessed by the galaxies. Inertia was supplied by the Big Bang to accelerate all particles radially outward. The present average velocity in our region is now "c". We can only notice this expansion due to acceleration of matter over very large expanses of separation such as the distance between galaxies. The distance changes between stars and planets is just too small to measure over mankind's span of time. And the velocity change measured in angstroms is too small to measure. Hence, it appears that no velocity change occurs, but this is why photons leave an object at the present speed of "c" without accelerating. All matter is expanding uniformly at the velocity of "c" throughout space. Different velocities can occur within this universal frame of reference as is witnessed by a growing animal cell, a moving car, or an orbiting planet. These velocities are so minute that there is no affect on the overall extremely large velocity of "c". Different velocities occurred because of discontinuties when energy was converted to mass via E = mc(2).

Perhaps the inertia of expansion of concentrated matter produces what we identify as gravity.

Please have patience with this drabble. Maybe you can shoot a hole in this thought experiment.

I don't understand your thought experiment well enough to shoot.

Note, however, that the idea of "inertia" probably doesn't apply to the expansion of space. Matter itself was not propelled anywhere by the Big Bang. And I don't know what it means to say that matter is expanding uniformly at any speed. Speed is relative; it must be measured with respect to something, and it is a matter of simple observation to determine that there is no uniform motion of matter, since if that were the case, we'd not observe any motion at all.

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