https://www.youtube.com/watch?feature=player_embedded&v=GOa2L8_IAnQ
This doco titled “When will time End”
Discusses a timeline of the demise of the universe in likely stages.
There is a mention that the universes increasing expansion rate is due to Dark Energy?
Is that correct? I thought there wasn’t much understand about Dark Energy.
And asserts that as gravity diminishes that Dark Energy affects on the expansion rate and acceleration of the universe hastens.
The notion of dark energy comes from the measured accelerated expansion of the universe, not the other way round.
The spacetime geometry of the cosmos (indicating the expansion of the universe) says that there is a form of energy that pervades the universe that is invisible apart from its effect on the spacetime geometry (which is how it was detected). The spacetime geometry tells us what the energy is in the general relativistic sense, but not what it is in the material sense.
The Einstein equation, the master equation that relates energy-momentum to spacetime geometry, may include a cosmological constant term that can be interpreted as a form of energy-momentum that differs from the usual energy-momentum by being indistinguishable from the vacuum. Whether or not the Einstein equation includes the cosmological constant depends on the interpretation of “energy-momentum” (whether or not it includes the energy-momentum of the vacuum). However, I should point out that the cosmological constant isn’t the only form of vacuum energy, but it is a form that does not dilute as the universe expands.
The cosmological constant is responsible for the accelerated (or decelerated) expansion of the universe. A constantly expanding universe has no cosmological constant† but it can be shown to have a form of energy-momentum that is indistinguishable from the vacuum (this dilutes along with the distinguishable form of energy-momentum as the universe expands).
† This is distinct from whether or not the Einstein equation includes it, being a property of the spacetime itself.
The Big Rip scenario is when the expansion of the universe becomes so rapid that the forces that hold things together will no longer be able to resist being pulled apart by the expansion of the universe.
KJW said:
The Big Rip scenario is when the expansion of the universe becomes so rapid that the forces that hold things together will no longer be able to resist being pulled apart by the expansion of the universe.
A Big Rip might be plausible if M/AM production at BB was differentiated by “BB space” taking up the AM position. If M and AM were separated in this way at BB this might also provide a mechanism for DE/expansion? This would assume that the energy state during BB is such that “space” exerts a template type influence on forming particles.
any intelligent beings that have arisen inside the big bang won’t allow the universe / time to end
simple self preservation
Riff-in-Thyme said:
KJW said:
The Big Rip scenario is when the expansion of the universe becomes so rapid that the forces that hold things together will no longer be able to resist being pulled apart by the expansion of the universe.
A Big Rip might be plausible if M/AM production at BB was differentiated by “BB space” taking up the AM position. If M and AM were separated in this way at BB this might also provide a mechanism for DE/expansion? This would assume that the energy state during BB is such that “space” exerts a template type influence on forming particles.
Under standard General Relativity, antimatter is indistinguishable from matter. In Einstein-Cartan theory (an extension of GR), matter and antimatter might be distinguishable, but I am unsure about this.
KJW said:
Riff-in-Thyme said:
KJW said:
The Big Rip scenario is when the expansion of the universe becomes so rapid that the forces that hold things together will no longer be able to resist being pulled apart by the expansion of the universe.
A Big Rip might be plausible if M/AM production at BB was differentiated by “BB space” taking up the AM position. If M and AM were separated in this way at BB this might also provide a mechanism for DE/expansion? This would assume that the energy state during BB is such that “space” exerts a template type influence on forming particles.
Under standard General Relativity, antimatter is indistinguishable from matter. In Einstein-Cartan theory (an extension of GR), matter and antimatter might be distinguishable, but I am unsure about this.
I’m not sure I would put BB time under GR. The difference between the two is momentum. “Space” as a quantity is the equal but opposite dynamic to what we understand as energy. If a BB is a singularity of superposition, it might be plausible that the energy from the production of AM is absorbed as “space” and acts as pendulum ballast to the momentum of the universe?
When the music stops. Turn out the lights, turn out the lights.
Under standard General Relativity, antimatter is indistinguishable from matter. In Einstein-Cartan theory (an extension of GR), matter and antimatter might be distinguishable, but I am unsure about this.
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Can’t you tell by putting them together? Putting matter and matter, or antimatter and antimatter, together creates twice as much of the stuff you started with. Putting matter and antimatter together should leave zip.
KJW said:
The Einstein equation, the master equation that relates energy-momentum to spacetime geometry, may include a cosmological constant term that can be interpreted as a form of energy-momentum that differs from the usual energy-momentum by being indistinguishable from the vacuum. Whether or not the Einstein equation includes the cosmological constant depends on the interpretation of “energy-momentum” (whether or not it includes the energy-momentum of the vacuum). However, I should point out that the cosmological constant isn’t the only form of vacuum energy, but it is a form that does not dilute as the universe expands.
I should remark that I have a tendency to focus on the geometrical side of the Einstein equation, whereas for cosmology, one needs to also consider the physical side of the equation (the energy-momentum). For this, one needs to consider an equation of state (the ideal gas law is an example of an equation of state). This leads to the Friedmann equations which relate the expansion of the universe to physical parameters such as density and pressure. The relationship between density and pressure is an important consideration because it determines how the universe expands if for example the universe is predominately matter or predominately radiation. Or conversely, how the universe expands can provide a clue to the physical nature of the energy-momentum. To illustrate this point, a matter-dominant universe (for which the pressure is zero regardless of the density) expands as t2/3, whereas a radiation-dominant universe (for which the pressure is a third of the density in relativistic units) expands as t1/2. By contrast, dark energy has a pressure that is approximately the negative of the density in relativistic units, and is thus not an ordinary form of energy-momentum.
Stealth said:
Under standard General Relativity, antimatter is indistinguishable from matter. In Einstein-Cartan theory (an extension of GR), matter and antimatter might be distinguishable, but I am unsure about this.
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Can’t you tell by putting them together? Putting matter and matter, or antimatter and antimatter, together creates twice as much of the stuff you started with. Putting matter and antimatter together should leave zip.
I’m referring to separate distributions of matter and antimatter. One can’t put them together if they are light-years away. If they do somehow merge, then they form radiation which can be observed as such, but this is not what I meant by “under standard General Relativity”, by which I meant gravitationally.
> The Big Rip scenario is when the expansion of the universe becomes so rapid that the forces that hold things together will no longer be able to resist being pulled apart by the expansion of the universe.
The latest information from Planck is that the Big Rip scenario is very unlikely.
mollwollfumble said:
> The Big Rip scenario is when the expansion of the universe becomes so rapid that the forces that hold things together will no longer be able to resist being pulled apart by the expansion of the universe.The latest information from Planck is that the Big Rip scenario is very unlikely.
Can you provide detail?
> The Big Rip scenario is when the expansion of the universe becomes so rapid that the forces that hold things together will no longer be able to resist being pulled apart by the expansion of the universe.
The latest information from Planck is that the Big Rip scenario is very unlikely.
In addition, the disproof of supersymmetry and similar theories from the Large Hadron Collider results pretty well rules out proton decay. Without proton decay, many individual atoms heavier than iron that are currently considered “stable” will eventually decay to lighter elements by spontaneous fission, but the lighter elements will be unconditionally stable. And that means that white dwarfs are forever.
And that means that the time to the end of the universe is governed by heat-death. The slow cooling by loss of photons into an ever-expanding universe. A solar mass black hole has a lifetime due to evaporation of 2*10^67 years. The Milky Way’s black hole has a lifetime of 10^87 years. The supermassive black hole in NGC 4889 has a lifetime of 10^98 years.
The alternative is that the metastability of the universe turns into instability, the universe is ripped apart in another big bang and everything begins again. Nobody, so far as I know, has managed to put a timescale on the duration of the stability of the metastable universe.