(1 - 2 GM/ r c^2) ^ 1/2 and Big Bang

In summary, the conversation discusses the equation t1 = t2 ( 1 - 2 GM/ r c ^ 2) ^1/2 and its implications for the size and temperature of the universe at the time of the Big Bang. It also addresses the application of Shwarzschild geometry to vacuum particles and their potential role in the formation of the universe. The main point of contention is whether the universe can be described as a spherically distributed matter with a vacuum outside, or if it is globally uniform. The conclusion is that the latter is more likely based on the current understanding of physics.
  • #1
kurious
641
0
In general relativity the equation
t1 = t2 ( 1 - 2 GM/ r c ^ 2) ^1/2
is often mentioned.
If the mass, M, is equal to the mass of the universe - 10 ^ 52 kg -
then r cannot be less than 10 ^ 24 metres without invoking
the idea that a time can be imaginary.
But could an equally valid interpretation be that the universe started
out no smaller than 10 ^ 24 metres?
The temperature of the universe one second after the Big Bang is
thought to be 10 ^10 K, and if the temperature of the cosmic microwave
background nowadays,
is extrapolated back from 10^26 metres to 10 ^ 24 metres, this would
give about this temperature [( 10^26 )^4 / (10^24)^4 x 1000 = 10^11 K
( the term of 1000 allows for redshift of cmbr photons).
The above scenario would mean that general relativity does not break
down at the time of the big bang and so quantum gravity might not be
needed to explain the Big Bang.
 
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  • #2
Shwarzschild geometry applies to vacuum outside a localized spherically symmetric matter distribution. It does not apply to uniform matter distributions of global extent. So, no.
 
  • #3
What if the matter is spherically distributed and the vacuum is outside the spherical mass distribution.If we associate the vacuum with vacuum particles, at the time of the Big Bang these particles might have existed outside the spherical mass distribution.
If the gap between the quarks and leptons in the spherical mass distribution was smaller than the average wavelength of a vacuum particle then the vacuum particles would have been unable to get into the sphere and so the vacuum would have existed outside it.The vacuum particles would have had to have had a wavelength of about 10^ - 3 metres.This is also the wavelength the cmbr photons would have had to be locked inside the sphere of mass.And it is a MICROWAVE wavelength!
 
  • #4
kurious said:
What if the matter is spherically distributed and the vacuum is outside the spherical mass distribution.

Then you don't have the universe that we actually have and so the predictions based on your localized matter universe model are irrelevent.
 
  • #5
DW

Then you don't have the universe that we actually have and so the predictions based on your localized matter universe model are irrelevent.

KURIOUS:
The universe we have now would not necessarily be the universe at the time of the Big Bang.If vacuum particles have wavelengths then what I have said is plausible.
It is most unlikely that vacuum particles do not have wavelengths!
 
  • #6
kurious said:
DW
KURIOUS:
The universe we have now would not necessarily be the universe at the time of the Big Bang.If vacuum particles have wavelengths then what I have said is plausible.
It is most unlikely that vacuum particles do not have wavelengths!

No, what I am referring to has nothing to do with the fact that they do have wavelengths. It has to do with the fact that their distribution is globally uniform, rather than confined to a sphere of finite extent.
 

What is (1 - 2 GM/ r c^2) ^ 1/2 and how does it relate to the Big Bang theory?

The term (1 - 2 GM/ r c^2) ^ 1/2 refers to the Schwarzschild radius, which is the radius at which the escape velocity exceeds the speed of light. This term is a key component in Einstein's theory of general relativity, which is the basis for the Big Bang theory. It represents the critical density at which the universe would stop expanding and begin collapsing.

How does the concept of (1 - 2 GM/ r c^2) ^ 1/2 support the evidence for the Big Bang theory?

The presence of this term in the equations of general relativity supports the idea that the universe began as a singularity, a point of infinite density and temperature. As the universe expanded, this critical density decreased, allowing for the formation of matter and the evolution of the universe as we know it.

What is the significance of c^2 in (1 - 2 GM/ r c^2) ^ 1/2 and its relation to the Big Bang theory?

The value of c^2, the speed of light squared, is a fundamental constant in physics and plays a crucial role in the equations of general relativity. In the context of the Big Bang theory, c^2 is used to calculate the energy density of the early universe and its expansion rate.

How does the value of GM affect the behavior of (1 - 2 GM/ r c^2) ^ 1/2 and its connection to the Big Bang theory?

The value of GM, the product of the gravitational constant and the mass of a celestial body, determines the strength of the gravitational force. In the context of (1 - 2 GM/ r c^2) ^ 1/2, a higher value of GM would result in a smaller Schwarzschild radius and a higher critical density for the universe. This demonstrates the role of gravity in the formation and evolution of the universe as described by the Big Bang theory.

How does the concept of (1 - 2 GM/ r c^2) ^ 1/2 relate to the expansion and age of the universe according to the Big Bang theory?

The value of (1 - 2 GM/ r c^2) ^ 1/2 plays a crucial role in determining the expansion rate and age of the universe. A higher value of this term would result in a faster expansion rate and a younger age for the universe. This aligns with the predictions of the Big Bang theory, which suggests that the universe is approximately 13.8 billion years old and has been expanding since its inception.

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