Global properties of the universe

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In summary, the global properties of the universe encompass its overall structure, dynamics, and evolution. Key aspects include the universe's large-scale geometry, which can be flat, open, or closed; its expansion rate, influenced by dark energy; and the distribution of matter and energy, which shapes cosmic structures like galaxies and clusters. Understanding these properties helps scientists explore fundamental questions about the universe's origin, fate, and the physical laws governing it.
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south
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Is there any relationship with global properties of the universe and it's own physical constants ?
Could some properties of universe, e.g. average density, size, CMB temperature, be determined by known physical constants, such as average nucleon mass, Avogadro number, Boltzmann constant, C, Stefan-Boltzmann constant, gravitational constant G , that is, usual constants?
 
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Many of the constants you mention are arbitrary conventions set by our choice of physical units. So mostly no for any of those.

To give any physical relevance, a constant must introduce something of physical relevance, such as the fine-structure constant.
 
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Thank you Orodruin for assisting me. What you expose is doubly interesting because it contradicts my expectation.

My expectation: If the universe exhibits characteristic constants, I expect that some global properties (without going into fine details) are tied to those constants and it is possible to calculate such properties by taking the constants as data.

Now I have given up my expectation. If it is possible to expand a little more, that would help me. Thank you.
 
  • #4
Orodruin said:
Many of the constants you mention are arbitrary conventions
And most, if not all, are not even constant!
 
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Vanadium 50 said:
And most, if not all, are not even constant!
Thank you Vanadium 50 for helping me.

Wow! My surprise grows. What you have expressed has lowered my expectations even more. What a science assumes to be constants are not constants? Things get fascinating. If it is possible for you to expand, it would help me.
 
  • #6
south said:
If it is possible for you to expand
That's the key. The universe is expanding. And cooling.

So its density is going down.
Its size is going up.
The CMB is becoming less intense and lower in frequency.
And so on.
 
  • #7
Does it mean that in this scenario my question refers to indeterminate terms?
 
  • #8
Vanadium 50 said:
And most, if not all, are not even constant!
south said:
known physical constants, such as average nucleon mass, Avogadro number, Boltzmann constant, C, Stefan-Boltzmann constant, gravitational constant G
I count half defined constants … unless you use geometrized units and also put G = 1. The Stefan-Boltzmann constant is also a combination of defined constants and is therefore also constant by definition.
 
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The range of information provided in the posts has grown. Compacting a little would help me. Can I extract, as a compact answer, that physical constants do not encode the global properties of the universe?
 
  • #10
south said:
that physical constants do not encode the global properties of the universe?
First, those are words. The truth is in the math.

Second, those are your words. We need to flesh out what you need.

Finally, you can complain that you didn't get a nice sound bite for an answer. But knowledge is not just a collection of sound bites.
 
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Thank you very much Vanadium 50. Your support is very useful for me.
 

FAQ: Global properties of the universe

What is the shape of the universe?

The shape of the universe is still a topic of research, but current evidence suggests that it is flat on large scales. This conclusion is based on measurements of the cosmic microwave background radiation, which indicate that the total density of the universe is very close to the critical density required for a flat geometry. However, the universe could still be finite and unbounded, similar to the surface of a sphere.

What is dark matter and why is it important?

Dark matter is a form of matter that does not emit, absorb, or reflect light, making it invisible and detectable only through its gravitational effects. It is believed to make up about 27% of the universe's total mass-energy content. Dark matter is crucial for explaining the observed gravitational effects on galaxies and galaxy clusters, which cannot be accounted for by visible matter alone. Its existence helps to explain the structure and formation of the universe as we observe it today.

What is dark energy and how does it affect the universe?

Dark energy is a mysterious force that is driving the accelerated expansion of the universe. It is thought to make up about 68% of the universe's total energy density. Its effects are observed in the way distant galaxies are moving away from us at increasing speeds. Dark energy is still not well understood, and its nature remains one of the biggest questions in cosmology.

What is the fate of the universe?

The fate of the universe is still uncertain and depends on the properties of dark energy and the overall density of matter. Current models suggest several possible scenarios: the universe could continue to expand forever (Big Freeze), eventually stop expanding and start contracting (Big Crunch), or reach a stable size (Big Chill). The most widely accepted scenario, given current observations, is the Big Freeze, where the universe continues to expand and cool over an infinite amount of time.

What is the observable universe?

The observable universe refers to the portion of the universe that we can see and measure, limited by the speed of light and the age of the universe. It is approximately 93 billion light-years in diameter. Beyond this limit, light from distant objects has not had enough time to reach us since the Big Bang. The observable universe contains billions of galaxies, stars, and other celestial objects, but it is only a small fraction of the entire universe, which may be infinitely larger.

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