# Tag Info

## Hot answers tagged universe

8

Disclaimer: Here is my metamathematical take (but read that as a very very very recreational bunch of statements). Gödel second incompleteness theorem says that the completeness of a logical theory (i.e. that every statement is true, false or undecidable) is not provable within the theory. However, if you are willing to assume proofs that "are more complex ...

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The size of atoms is determined by the strength of the electromagnetic force, the mass of the electron and some other constants like the value of Planck's constant. If the size of atoms was changing it means that one or more of these constants must be changing. The trouble is that these fundamental constants crop up all over the place in physics, and if ...

2

How can one predict the future of such a universe when inter-universal travel is possible and the multiverse is not perfectly mathematically describable? Inter-universal travel should NOT be possible if you are speaking of multiverses in the usual sense of inflationary cosmology. The idea of one universe being separate from another hinges on the idea ...

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The ultimate fate of the universe (and here I'm taling about things on cosmic scales not what happens to stars and galaxies etc.) depends on the equation of state of the material within it. In cosmology the equation of state is represented by a dimensionless number that is the ratio of the pressure to the (energy) density. i.e. $$w = \frac{P}{\rho}$$ and ...

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I've heard that some physicists think that the net energy of the universe is zero. Me too. They talk about gravitational energy being negative. But see Einstein talking about gravitataionl field energy here. It's positive. For this to happen, I would assume that the negative gravitational energy of a body ought to cancel out its rest energy. That's what ...

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The ratio of dark to baryonic matter is 5.25 in the first diagram and 5 in the second diagram, but I don't think the difference is significant. We don't know the densities with absolute certainty, especially near the Big Bang, and the small difference between the ratios is probably just down to the uncertainties in the densities. We would expect the ratio ...

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Snap your fingers. Wait. Snap them again. Physically speaking, time is a measurement which distinguishes between these two different events (finger snaps) which happen non-simultaneously (snap, wait, snap) at the same spacial location. There is no reference frame in which these events happen simultaneously. That's the simplest way I know to define time. ...

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In your model, of everything stretching, there would be no way to observe any stretch. We would live in static dimensions as far as we are concerned. It is our observations of the way the stars, galaxies and clusters of galaxies behave that has led to the idea of an expanding universe : Hubble inferred the recession velocity of the objects from their ...

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As the comments to the questions state, this is a question on the research state about the generation of the universe, and the first moment is modeled in the Big Bang model. The real beginning point is not yet known even in this model since gravity has not been consistently quantized within the model, only effective theory is used. Nevertheless existing ...

1

Given that we can only interact or observe the universe out to a certain distance, it isn't possible to test whether the universe is infinite. Even if it is, the parts of it beyond a certain distance are inaccessible to us through any means, because all information is limited to the speed of light, including the travel of gravitational waves and massless ...

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This part of Lawrence Krauss' brilliant "A Universe from Nothing" lecture describes the fate of an expanding universe quite well. Long story short, because the expansion of the universe is accelerating, in a hundred billion years or so the rate will exceed the speed of light (this doesn't require objects to move through space faster than light, that's ...

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