Science a GoGo's Home Page Forums General Discussion General Science Discussion Forum Dark energy and topology

This is a mind experiment involving the ?time arrow?, dark energy, topology, and maybe some other stuff: Here we sit in our universe, making observations that tell us that the expansion of the universe is accelerating. The scientists interested in this phenomenon theorize a ?dark energy? that gives rise to a repulsing force acting on all bodies in our universe, as an explanation. Of course this looks like a repulsing force because of our ?time arrow?, our perception of which events follow others. If we reverse the time arrow and thereby run the ?film? backwards, gravity appears to repulse, objects fall upwards from the surface of the earth, and the universe is contracting at an ever faster rate. This effect of ?dark energy? now looks like the effect of gravitation. In our reversed arrow universe we are heading for the ?Big Crunch?. It is this symmetry that nags my mind. I haven?t taken it as far as it can go, and so I am inviting others with better knowledge of these topics to consider the picture I have described, and to reply with their take on this different view of dark energy.

Time does not reverse. Trivial demo: Take a motion picture film can (pancake cylinder much wider than it is thick). Weld a port through the center of one face. Weld the edge seam. Weld a tangential port through its edge. Fill with water.

1) Pump water in through the middle and it goes out through the edge nice as you please. Push through a nice fat flow under pressure. No problem.

2) Reverse time. You now have water inflowing tangentially and out through the middle without swirling. This violates conservation of angular momentum. CF: Feynman' sprinkler experiment.

The two-port film can construct is a fluid diode with no moving parts. Water only easily flows in one direction. There is no time reversal symmetry.

Entropy is often alled "time's arrow." Entropy is only a statistical arrow of time. Angular momentum is absolute.

Sorry Al, but angular momentum would still be conserved in the time reversed case. The angular momentum of the water would be transferred to the axis holding the sprinkler, producing a torque, just like in the time-forward case, where non-swirling water flows in and swirls out, producing an opposite torque on the can.

OK. Either way, this is a mind experiment meant to point out the apparent symetrical similarities of gravitational force and dark energy. Sometimes looking at a phenomenon from a different frame of reference aids understanding, or maybe suggests a different approach to investigation. I am not proposing that time can be made to run backwards. Only suggesting that it is an alternate approach in thinkintg about dark energy. So does this intrigue anyone?

Dark Energy is a term used by Scientist, because they dont really know what the driving force is, that is making matter receed ever faster with distance. We may never know, and may have to theorise as to the various possibilitys.
Were the Universe to be shaped like a gigantic thick Catherine wheel, and spinning.....everything on our periphery, being subject to centrifical force would be moving out, faster than ourselves.
Likewise everything 'back' towards the 'center' would be moving out but at slower speeds dependant upon their distance from the gravitational center.
Simplistic yes, but in terms of Billions of light years as we look out in any direction, it could provide another answer that satisfies your query?

The Catherine wheel idea works in 2-dimensions, but if I understand the scientists' description of the expansion, it appears to be 3-dimensional, the acceleration of the expansion rate appears to be the same in all directions at all distances that can be measured (beyond the Sol system).
OK, here's a slightly different image to consider: The Universe is contained in a (much larger) spherical source of gravitational attraction maybe made of stuff like neutron stars or black holes. This gets rid of the pesky reversed "time arrow" thing, and appears to describe the observed expansion behaviour. I'm not saying that if we could travel sufficiently far beyond the edge of the universe, we would find this shell made of black hole stuff, just that what we can see and measure behaves as if something like that is out there. Note that I don't think that this attractor shell is any easier to accept than dark energy, but I am happier with something that behaves like gravity than with something that behaves like anti-gravity (maybe a personal limitation) Comments invited.

Well yes,its another idea to be thought about.
Are you implying is that there is an eventual finite size of our Universe? That it is shaped like a gigantic sphere, where all the matter that is rushing away from us is eventually collecting?
So that eventually in the distant future there will be more mass (gravity) collected at the limits of this spherical shell, than there is now.
And could be a cause of our expansion ever outward?
You have an interesting idea, that is certainly new and unique. Prehaps you ought to pursue it.
Like see if there is any possibility of matter looking more dense, or closer together, given our present limits of optical Astronomy.

I'm more exploring ideas than implying the sphere shape. Not being a physicist nor a mathematician, I read the descriptions of the effects of this "dark energy" and drew my own inferences (not conclusions). If a mathematician or physicist looks at these musings and explores a new and hopefully fruitful path as a result, then I am happy.

It seems every one agrees that the so called ?dark energy? is a creation to assist in the answer as to why the distant objects in the universe appear to be racing away from us.

The ?speed? of the objects may simply be created by the means used to measure them. I know it is impossible and at the very least untenable, BUT, there is another prospective answer to the mystery. We determine the apparent exodus of systems going away from us by looking at the light they send us. So the first prospective clue should commence on the means we use to investigate the light. The red shift, I believe, is the method by which we conclude that a Doppler effect denotes a speed factor for all objects which show a red shift when studied. The fact that the farthest objects show a greater redshift ?tells us? such an object is moving away and furthermore the larger the red shift the faster it is moving.

The untenable solution might possibly be, as I see it that the light we see from the most distant objects traveled farther to get here. That light we see from all distant objects is moving faster than we think and the farther it travels the faster it will be going meaning that what we interpret as a red shift due to a Doppler effect is not a real time interpretation of what is happening. If, if, we are mistaken about the quality of here at earth and elsewhere in the universe, and if light from distant places was traveling faster than our sun light, we would see exactly what we find. When that light entered the sun?s gravitational field it would be compressed to our slower speed in giving a different basis for a red shift than what we interpret it to be. This would be in total agreement with observation because the farthest light is most likely the fastest tricking us into thinking the source is going away from us. This is one crazy idea of mine in my book; Surfing the Solar System.

I know this is impossible, that it is against all current theory and all current testing- nice, however, because it eliminates the expansion and the need for dark matter while potentially providing answers to other unresolved issues.

I do not expect to find believers.
Jim Wood

An interesting concept. If it is to be widely accepted as even a theory, somone would have to come up with a scientifically acceptable way to test either the whole thing, or at least some specific aspect of it. As many others have reminded the community, a scientific theory must be scientifically testable. It should make predictions that can be experimentally tested.
On the other hand, if >>belief<< is desired, then it may be more in the realm of philosophy or religion.

For the time being, I tend to regard the concept of dark energy as more philosophical than scientific. I would like to see the results of a scientific experiment that measures some aspect of dark energy not explainable by some other, better-understood, phenomenon.

You have an excellent point. Proof of any theory or prospective answer to a question is mandated. How does one go about measuring the speed of light? If the issue is whether light coming to us from great distances is traveling faster than the light we measure here at earth then it requires a means to measure the light from outside the gravitational field of the sun or we will simply repeat what we already have learned by previously testing.

If however, light has the potential for increased speeds in excess of what we have previously measured and its arrival here at earths vicinity provides a red shift that appears to be do to the going away of the source as opposed to the heading towards us by the source then, I suggest that there is a way to test it.

Let?s take the light reflected back to us from the planet Saturn when our respective orbits present Saturn in position when Earth is gaining on Saturn?s orbital position and do it again when the Earth is orbiting away from Saturn?s position. This is not the best test but Earths movement should simulate the effect of Saturn coming towards us and thereafter going away from us. If the reflected light from Saturn shows a greater red shift when Earth is towards Saturn this may simulate what I claim is happening with light from distant sources. If there is no difference shown by the coming and going it may be an artifact related to reflected light as opposed to direct Star light.

I do not have the skill or access to the means to conduct such a test and I doubt any one that does have it would bother to do it.

Jim Wood

The first measurement of the speed of light (approximate) is attributed to the Danish astronomer Olaf Romer in 1675. He used excellent reasonong and very crude tools by today's standards. There is also an intersting explanation on how the speed of light is defined and related maters at http://www2.corepower.com:8080/~relfaq/speed_of_light.html
My point being that good, logical reasoning and careful preciseness of language in discussion and writing go a long way toward arriving at good conclusions. Don't apply too much reverence to expensive scientific apparatus.

Hi bob@gh:

I put reverence in nothing. I can not even recall an occasion when I may have thought of the word, let alone applied it.

When the original determination is made of a fact by "expensive scientific appartus" then to test an apposing idea similar equipment is going to be required. The original measures of the speed of light were not really concerned with a red shift. That came later thanks to Hubble, I think. We are speaking of PROOF, recall?
Jim Wood