All Questions
Tagged with big-bang-theory cosmology
38
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Big bang cosmology [closed]
What is the main evidence that the Big Bang is real. Why can we know that the big bang exists. In a short summary,
the evidence? In your owns words?
- 227
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Why is it assumed that the universe started out with a size equal to the Planck length?
What if the Planck length is the distance between particles when the universe was very small .
For a spherical ball of 10^ 78 protons that would give the universe a radius of 10^26 X 10^-35 = 10^-9 ...
user50623
17
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1
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Why do cosmologists assume that inflation began shortly after the Big Bang, rather than at the exact start?
Somehow, I have never come across an explanation of why cosmologists claim that the alleged inflation of the very early universe occurred not at the Big Bang, but very shortly afterwards (~10^-36 to ...
- 5,177
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Could inhomogeneities or topological defects break the fundamental symmetries of the Universe?
I have heard that some types of inhomogeneities and topological defects in cosmology have been proposed to be able to break fundamental symmetries of nature such as the Poincaré, Lorentz, ...
- 1,017
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Redshift distance proportionality at high Z and need for "mighty mouse" galaxies?
Allegedly supported by some evidence from the new James Webb space telescope physicist Eric Lerner has written an article that have garnered some attention. He writes that:
"Put another way, the ...
- 457
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Expansion rate of an infinite universe at the Big Bang
If the universe is infinitely large, then any two arbitrarily distant points must have been arbitrarily close together at some earlier point in time. Doesn't that mean that the expansion rate of the ...
- 123
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Does the Cosmic microwave background (CMB) have an amplitude? Does it vary, like the 'temperature' (wavel./freq.) and the polarization?
Somehow, I have never read about this or thought about, until now...
Does the number of photons from the CMB hitting us from all directions vary at all?
- 5,177
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Strange plot in Max Tegmark book, Our Mathematical Universe
In Max Tegmark's book, Our Mathematical Universe, we can find (in chapter 5, figure 5.3) the following (horrible and poor quality) plot that is supposed to highlight the extreme sensitivity of the ...
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Why was the Cosmic Microwave Background (CMB) released at a blackbody temperature of 3000K rather than 30,000K?
If the ionization (or reionization, or Recombination) energy of atomic hydrogen is 13.6 EV, which corresponds to a black body temperature of 30,000K, why did the CMB not begin to appear then?
Why did ...
- 5,177
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Why isn't the CMB blurred by the blackbodies emitted in the time after atoms first formed?
I am confused about why the light released from the moment when gas first formed was so dominant in comparison to the light released afterwards. Why isn't the CMB in interference with a series of ...
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How did the Universe climb out of its own Big Bang black hole?
The Big Bang started as a singularity. That means small. All the matter in the universe was in a volume smaller than its own Schwarzchild radius. The universe was inside a black hole.
At present, the ...
- 1,113
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How can scientists deduce the number of types of neutrinos, or 'effective number', from Planck satellite data?
Is it related to the way they deduce the Hubble constant from Planck data?
Would more types of oscillating and mixing neutrinos mean faster or slower expansion of the universe?
Would a fourth mass ...
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2
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77
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How do we know or predict which particles were present before Big Bang Nucleosynthesis occurred?
I'm reading Carroll and Ostlie's "An Introduction to Modern Astrophysics". In the BBN section, they describe that the universe contains a mixture of photons, electron-positron pairs, and ...
- 1,111
8
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What is the history of the average pressure, density, and temperature of the matter in the universe over time?
This question is inspired by this more specific question where Cerelic wanted to know if conditions were suitable for liquid water to exist during an epoch when the characteristic temperature of the ...
- 3,934
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Shouldn't the estimate of the universe's age be higher, not lower, after the attractive strength of gravity is taken into account?
From 'Fundamentals: Ten Keys to Reality', by Frank Wilczek :
"Running the movie of cosmic history backward in our minds, we found the galaxies all coming together to meet at a definite time. ...
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