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The Big Bang Theory is a much more general and less specific description of our theory about the origin of the Universe than the $\Lambda{\rm CDM}$ model (by the way, I don't think that the hyphen is written in that acronym). The Big Bang Theory says that the Universe was expanding and the distances between two places where galaxies sit today used to be ...


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The explosion that you have seen is actually 4 dimensional representation of the universe. if we are representing universe in 4D then big bang had happened at a point and is expanding as a hollow sphere.But in 3D the big bang should have happened in every point to the universe and is expanding to every direction.This interpretation is using Friedman model of ...


4

One of ideas associated with string theory is the ekpyrotic universe. This starts with brane cosmology i.e. the idea that our universe is a four dimensional brane floating around in the ten dimensional string theory spacetime. There will be many such brane worlds and the ekpyrotic idea is that a collision between two branes would appear just like the Big ...


2

In general relativity, the field equation relates the metric (through the associated curvature tensor) to the stress energy tensor $T^{\mu\nu}$. This can be interpreted as a flux of energy and momentum in spacetime (i.e. integrating $T^{\mu\nu}$ over a spacetime hypersurface, like a three dimensional hypersurface of constant time, tells you the rate at which ...


2

The statement that at the beginning of the universe energy/mass was concentrated in a single region under conditions of extreme temperature and density is usually extrapolated from experimental data on the energy/mass content of the universe and its expansion, which is then analyzed through the classical (i.e. non-quantum) theories of general relativity and ...


0

This paper explains the importance of physical mechanisms existing which can function as clocks at various eras. Your question is not simple Abstract We provide a discussion of some main ideas in our project about the physical foundation of the time concept in cosmology. It is standard to point to the Planck scale (located at ∼ 10−43 seconds after ...


0

Well, the observations of the acceleration of the universe's expansion is perhaps the strongest argument against the Big Crunch argument. Nonetheless though, it is by no means a disproven theory- we cannot very accurately predict the future until we understand the 95% of the universe that isn't baryonic matter, the 95% that current theories have as the ...


2

Until dark energy (and dark matter) are properly understood, it is impossible to be certain of the future fate of the universe. The concordance $\Lambda$CDM model, deduced from observations of distant supernovae, from the cosmic microwave background and from baryon acoustic oscillations suggest that the expansion of the universe is accelerating and that ...


0

I am not an expert to give the most proper answer but according to Hubble's law , the most distant galaxies are moving away from us faster than the speed of light, due to space expansion. This fact makes me think that also the gravitational effect of these galaxies is lost forever, and this looks to be the future of our universe. Even if a 'big crunch' ...


1

EDIT: if i got it right , the answer to my question has to do with space-expansion , but to be honest i can't understand why. In an hypothetical situation that universe stops expanding and starts shrinking, we won't be able to detect such radiations anymore? One has to think of our three dimensions we live in and the effect of expansion or ...


4

Conformal space is nice because in it, photons have straight world-lines, so we can easily see what we must do to achieve causal contact between two points in the CMB, after the physical time $t_i=0$ of the initial singularity, but before the physical time $t_{\text{CMB}}$ of decoupling. Since we have \begin{equation} d\tau=\frac{dt}{a(t)}, \end{equation} ...



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