Future of Universe: Big Freeze, Big Rip, Big Crunch, Big Bounce?

[Clayjay]

The bit about gravitational energy is entirely incorrect. It's about 30% matter (currently). Gravitational energy is a somewhat nebulous concept which would be extremely misleading to use in this context, because dark energy influences the expansion history through gravity as well. It's just that different kinds of matter have different impact on the expansion rate.

It looks to me we are both correct in the context we used. The universe is roughly 70% dark energy and 30% gravity or matter. The universal gravitational constant coverts the terms. The whole universe is 100% divided into 70% dark energy plus 25% dark matter and 5% ordinary matter. Of the 30% that is 100% gravity 83.33% of the gravity is attributed to dark matter and 16.66% to ordinary matter. It was my responsibility to communicate clearly but I didn't. I will try to improve. Thank you for your help.

Dark energy also doesn't "expand space". The expansion is already there. Dark energy just prevents the expansion rate from falling too low. It acts, in effect, as a repulsive force.

"The expansion or already there" is a useful reasonable perspective. However Big Bang logic starts with a singularity that contained 100% of space-time. There was no space before space-time and the statement "expansion already there" is unsupported by Big Bang theory. All points in space today where one point in the beginning. True - that BB was a point in time and not space. True - there was no space before time. Logically time is primary or a prioriand space a posteriori. Inmy view, the concept of space-time is unified and looses meaning if therms are separated.

In order to get a handle on what the makeup of the universe means, you have to look at each component individually.

Does the context-logic of your statements have a unified principle in it? I think there is miscommunication galore here because of the diametric frameworks of classical and quantum cosmology. Classical physics is built on deductive logic while quantum mechanics uses inductive logic. Classical physics and Quantum mechanics have different ways of knowing things.

In my opinion it is a common misperception that cosmology is a branch astrometry. It seems to me that science is a branch cosmology. In prehistorical time cosmology had magical answers and legends. Through the Greek’s “Natural Philosophy” magical thinking was removed and replaced with logic. Logic can be viewed as having two branches, deductive and inductive logic. Classical physics is a result of deductive logic, where as quantum mechanics is a result of inductive logic. I experienced this divergence during my advanced physics studies as classical physics failed at the atomic level where the phonon or quantum level physics account for the data. Classical physics and quantum physics are both logically self-consistent but at the atomic level the logic methodology flips from deductive to inductive. A difference I think that is worth knowing for a cosmologist.

 

[Chalnoth]

It looks to me we are both correct in the context we used. The universe is roughly 70% dark energy and 30% gravity or matter. The universal gravitational constant coverts the terms. The whole universe is 100% divided into 70% dark energy plus 25% dark matter and 5% ordinary matter. Of the 30% that is 100% gravity 83.33% of the gravity is attributed to dark matter and 16.66% to ordinary matter. It was my responsibility to communicate clearly but I didn't. I will try to improve. Thank you for your help.

These aren't percents of gravity. That doesn't really make sense. These are percents of the current average energy density of the universe.

"The expansion or already there" is a useful reasonable perspective. However Big Bang logic starts with a singularity that contained 100% of space-time. There was no space before space-time and the statement "expansion already there" is unsupported by Big Bang theory. All points in space today where one point in the beginning. True - that BB was a point in time and not space. True - there was no space before time. Logically time is primary or a prioriand space a posteriori. Inmy view, the concept of space-time is unified and looses meaning if therms are separated.

As the singularity is an artifact in the equations that never occurred, this paragraph makes no sense. Big bang logic doesn't start with a singularity at all. It starts with the concept of a homogeneous, isotropic universe.

It's very useful to get out of the paradigm of the universe as a narrative, with each part building on the next. The problem with that paradigm is that our image of the earliest times is the most uncertain, so that if we relied upon models that were narratives, we'd never be able to get at the truth.

Scientific theories are not narratives. They are not stories where some early event leads to some later event. They are attempts to explain the structure and behavior of our universe.

Does the context-logic of your statements have a unified principle in it? I think there is miscommunication galore here because of the diametric frameworks of classical and quantum cosmology. Classical physics is built on deductive logic while quantum mechanics uses inductive logic. Classical physics and Quantum mechanics have different ways of knowing things.

In my opinion it is a common misperception that cosmology is a branch astrometry. It seems to me that science is a branch cosmology. In prehistorical time cosmology had magical answers and legends. Through the Greek’s “Natural Philosophy” magical thinking was removed and replaced with logic. Logic can be viewed as having two branches, deductive and inductive logic. Classical physics is a result of deductive logic, where as quantum mechanics is a result of inductive logic. I experienced this divergence during my advanced physics studies as classical physics failed at the atomic level where the phonon or quantum level physics account for the data. Classical physics and quantum physics are both logically self-consistent but at the atomic level the logic methodology flips from deductive to inductive. A difference I think that is worth knowing for a cosmologist.

Whaaa?? Um, no. All of science combines both inductive and deductive logic. Classical physics and quantum mechanics certainly do not have different ways of knowing things. Quantum mechanics is the physics which is needed to describe the behavior of the universe on small scales or cold temperatures.

 

[PeterDonis]

Big Bang logic starts with a singularity that contained 100% of space-time.

"Spacetime" is not the universe at one instant. It contains the entire history of the entire universe. So even if the initial singularity were part of spacetime (which it isn't, as Chalnoth pointed out), it would only be a very small part; it would not be 100% of it.