Is the Universe an open or closed system?

Question

I understand that knowledge of the origins of the "Big Bang", how it happened or what was before it, can only be theorized. But it seems to me that considering what has been observed (ie: that 4% of the universe is regular matter, 20% or so is dark matter, and the rest is "dark energy"), that the universe must be open. This would be the only way to explain the observed expansion and give reason for its acceleration. That is to say that gravity is leaking out or energy is leaking in or both, from some parallel universe. All this is based on my understanding of string/super gravity 11th dimensional theory.

If it is closed, and the total amount of energy and matter in our universe is fixed, then almost by necessity something external must be pulling on the boundaries of our universe causing it to expand. Something that is truly a VACUUM.

Does this seem reasonably logical?

Answer 1

there s nothing like open or closed universe i will say its open and expanding.

When people say it's expanding like a balloon you immediately think that the universe is the 3D space inside the ballon. In fact it's the 2D surface of the balloon. If you fly forever in space you will arrive back at your origin, just like if you went along the surface of the balloon.



That also helps understand gravity. When you place objects on a sheet of rubber (like our balloon) they dent inwards. The larger the mass, the deeper the dent, and the more things nearby that get dragged towards them.



Except in reality it's 3D space (not a 2D rubber surface) and we're expanding into 4D space (not the 3D space inside the balloon).

but thats only a theory

Answer 2

In fact, we don't KNOW that the universe is a closed system. We infer that it is because we don't observe any interaction with any elsewhere. (We might be able to observe an interaction without being observing the elsewhere itself.)



But lots of smart people have compared our universe with a black hole, and we know that black holes evaporate over a time,



dt = M^3 15360 pi^2 G^2 / h c^4

dt = (1.261684E-16 s kg^-3) M^3



For my derivation of this expression, see my Comments on question:

http://au.answers.yahoo.com/question/ind...



Now, from the OUTSIDE the evaporation of a black hole looks like blackbody radiation. Hawking radiation has the same distribution in wavelength as blackbody radiation does, for the same equivalent temperature.



The question is: what would the evaporation of a black hole look like from the INSIDE? And, maybe, the answer is that energy is not quite conserved. Because of the size of our universe (M=2E53 kg), the associated evaporation time is about 1E144 years.



The average rate of mass loss, during all that time, from the whole universe, would be 2E-91 kg/year, or 2E-79 grams per billion years. From the whole universe, one electron or one positron, or photons adding up to about half an MeV, would be disappearing each 5E60 years. The present, instantaneous rate of mass loss would be much less than that, of course. And the universe is only 1.36E10 years old.



The point is, we would not be able to tell the laws of thermodynamics in our universe had an exception which was this small. So there is a theory that predicts that our universe is not strictly a closed system, but that the difference isn't worth making much fuss about.

Answer 3

Maybe yours is "the only way to explain the observed expansion..." within the confines of big bang theory, but if you free yourself from that straight jacket, other possibility may open up.



"Open universe" is usually used in the sense of expanding for ever because of insufficient gravity. You seem to be saying, "open", in the sense that there are inputs and outputs from outside our universe.



In the thermodynamic sense, a finite universe is usually presumed to be closed; so the entropy of the universe is "obviously" increasing. I believe the thermodynamic closure of a static infinite universe is indeterminate. An expanding universe, whether finite or infinite, has an input of new space which makes it open in the thermodynamic sense.



Where that new space comes from probably can never be answered to a scientific certainty. Whether it comes from another universe, from an invisible source in our universe or from God, it would be an establishment of religion for the government to take a stand on this issue.



I have my own Fractal Foam Model of Universes, which offers a novel explanation of expansion and dark energy. The cosmic foam of our universe is the ether foam of a super-universe, and the ether foam of our universe is the cosmic foam of a sub-universe.



Ordinary energy consists of ethereal shear waves moving at the speed of light; dark energy consists of ethereal pressure waves moving at the speed of gravity force (greater than 20 billion c). Exchange of momentum between shear waves and pressure waves causes some shear waves to orbit one another, converting their energy to mass.



The expansion of our space stretches the bubble walls of our cosmic foam (walls of galaxies) until they pop. When a cosmic-foam bubble wall pops, two bubbles become one; that reduces the super-universe by one quantum of space; but time inversion turns that into an increase of one quantum of space. Thus, the expansion of our space and the inversion of time drive the expansion of super-universe space. Similarly, the expansion of sub-universe space and another inversion of time drive the expansion of our space.



When a cosmic-foam bubble wall pops, pressure waves radiate thru the cosmos. With time inversion, those pressure waves in the super-universe converge, causing the bubble wall to un-pop. (This puts a new twist on the question of whether cause preceeds effect. It also adds credence to multiple universes in the same place, time and scale.) Likewise, the pressure waves in our ether converge, causing an ether-foam bubble to un-pop, and generating a quantum of new space in our universe. Therefor, ethereal pressure waves perform the role of dark energy.



Every second, in every cubic meter of our ether, about 10^52 quanta of new space are created, averaging approximately 10^-105 cubic meter each.