What is the initial temperature of the Big Bang?

In summary, the temperature of the Big Bang is thought to be around the Planck temperature, but this is not a well-defined concept as the Big Bang is a process and not an event. Some sources may mention a temperature at the beginning of the Big Bang, but this is not a widely accepted or well-understood idea. The temperature of the plasma that emitted the cosmic microwave background radiation can be estimated based on its redshift, but this is not the same as the temperature of the Big Bang. Ultimately, the question of the initial temperature of the Big Bang may be better understood by considering the energy density of the inflaton, but this is not currently known.
  • #1
wolram
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We all know that the temperature of the back ground radiation is 3k, but how have we calculated the intiial temperature of the big bang.
 
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  • #2
No such thing.
 
  • #3
wolram said:
We all know that the temperature of the back ground radiation is 3k, but how have we calculated the intiial temperature of the big bang.
The closest thing to an "initial temperature" that makes sense in this context would have been the temperature right after reheating, which was caused by the end of inflation. Because reheating would have been caused by the inflaton decaying, the temperature at that time would have been determined by the final energy density of the inflaton. That energy density we don't currently know.

Note that there are also some alternatives to inflation, and some of them may have rather different early temperatures, while others won't have anything that can be referred to as an "initial temperature" at all.
 
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  • #4
The temperature of the BB is thought to be around the Planck temperature [really, really hot]. The temperature of the plasma which emitted CMB photons is proportionate to its redshift [z~1090].
 
  • #5
Chronos said:
The temperature of the BB is thought to be around the Planck temperature [really, really hot].

Where do you get this? As the BB is a process, not an event, I don't think this is even meaningful.
 
  • #6
I agree properties like like time, space and temperature are undefined at t=0. It is not until after the briefest possible span of time has passed following the BB [t=10E-43 seconds], that temperature has any meaning, and that temperature is the Planck temperature. I'd call that close enough for government work.
 
  • #7
But it's not the Planck temperature. It's like 1/3 the Planck temperature. It's also the least understood point.

The question is analogous to "how far is it to Boston?". Arguing whether the best starting point is Worcester Mass. or Worcester England seems not to be a good answer to this question.
 
  • #9
There's lots of such things out there. I don't get my science from them.

The Big Bang is a process, not an instant, so there is no "temperature of the Big Bang". That's more important than the factor of three you bobbled in trying to define one.
 
  • #10
As this is a beginner's level question which has been adequately answered, I think its time we closed this thread.

Thank you all for your contributions.

Take care,
Jedi
 

1. What is the estimated temperature of the Big Bang?

The estimated temperature of the Big Bang is about 10^32 Kelvin (K) or 10^32 degrees Celsius (°C). This extreme temperature is over a billion times hotter than the core of our sun.

2. How do scientists measure the temperature of the Big Bang?

Scientists use various methods to measure the temperature of the Big Bang. One way is by studying the cosmic microwave background (CMB), which is the leftover radiation from the early universe. By analyzing the distribution and intensity of this radiation, scientists can determine the temperature of the Big Bang.

3. Has the temperature of the Big Bang changed over time?

Yes, the temperature of the Big Bang has changed over time. As the universe expanded and cooled, the temperature gradually decreased. It started at an infinitely hot and dense state and has cooled to the current temperature of about 2.73 K.

4. How does the temperature of the Big Bang relate to the birth of the universe?

The temperature of the Big Bang is a crucial factor in understanding the birth of the universe. It represents the moment when all matter and energy were compressed into a single point, also known as the singularity. As the universe expanded, this intense heat energy began to spread out, creating the universe as we know it.

5. Is the temperature of the Big Bang the hottest temperature possible?

The temperature of the Big Bang is considered to be the hottest temperature that has ever existed. However, it is not the maximum possible temperature. The laws of physics as we know them break down at extremely high temperatures, so it is unknown what the maximum temperature could be. Some theories suggest that the maximum temperature could be up to 10^32 K.

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