Fundamental physical constants

In summary: I would have much to add. I think it is an interesting question, but I have no idea where to start looking for an answer. I believe that the CODATA update was from 1986 from a brief search, but I couldn't find what was changed in that update.In summary, the fundamental physical constants are called "constants" because they are arbitrary values used in equations and physics. These values do not change in different universes, but they can change over time as our understanding and measurement of them improves. In 1986, there was a notable adjustment of the constants, which had implications for the establishment of standards for electrical units. Despite these changes, the exact values of the constants remain a mystery and continue to
  • #1
Serra Nova
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Why are the fundamental physical constants called "constants" when they change over time?
I've read that the constants were adjusted in 1986.

How can there even be something that is constant, when we can't even see the entire universe?
 
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  • #2
Serra Nova said:
Why are the fundamental physical constants called "constants" when they change over time?
I've read that the constants were adjusted in 1986.

How can there even be something that is constant, when we can't even see the entire universe?
The constant are arbitrary values which we can use for our equations and our physics.
 
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  • #3
  • #4
Serra Nova said:
But why do they have those exact numerical values?
https://physics.nist.gov/cuu/Constants/Table/allascii.txt
They just happen to have these values. We don't know why pi happens to be 3.1415, it just is. These values can help us understand the universe but they could easily be something else.
 
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  • #5
lekh2003 said:
They just happen to have these values. We don't know why pi happens to be 3.1415, it just is. These values can help us understand the universe but they could easily be something else.

I hope future particle accelerators will shed some light onto this. Thank you for teaching me.
 
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  • #6
lekh2003 said:
They just happen to have these values. We don't know why pi happens to be 3.1415, it just is. These values can help us understand the universe but they could easily be something else.

Brian Greene said that those exact values might have different values in other universes.
 
  • #7
Serra Nova said:
Brian Greene said that those exact values might have different values in other universes.
Yes, that was in his book. He did outline that the specific constant we had were ideal and that it could've been anything.
 
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  • #8
Serra Nova said:
I've read that the constants were adjusted in 1986.
I haven’t read that. What is your source?
 
  • #9
Serra Nova said:
Why are the fundamental physical constants called "constants" when they change over time?
I've read that the constants were adjusted in 1986.

There is no convincing evidence that the fundamental constants change with time In terms of why they have the values they do, nobody knows. Referring to the fine structure constant, Feynman said, "It's one of the greatest damn mysteries of physics: a magic number that comes to us with no understanding by man."
 
  • #10
Dale said:
I haven’t read that. What is your source?

I suspect the OP is referring to some CODATA update (although I can't of any major change in 1986).

Note that a bunch of fundamental constants will change (and some will be assigned exact values) later this year when the SI is redefined. This is not because something has actually changed in nature; it is just because we will will tweak our system of units somewhat to make it a bit more self-consistent.
 
  • #12
f95toli said:
I suspect the OP is referring to some CODATA update (although I can't of any major change in 1986).

Note that a bunch of fundamental constants will change (and some will be assigned exact values) later this year when the SI is redefined. This is not because something has actually changed in nature; it is just because we will will tweak our system of units somewhat to make it a bit more self-consistent.
"The 1986 adjustment of the fundamental constants has implications with respect to the establishment of standards for electrical units".
https://link.springer.com/chapter/10.1007/978-94-009-2955-5_5
 
  • #13
I think OP is referring to "Since they are constants, the definition of constant itself states that a constant is something that doesn't change, how can they change?". I think that is the OP's question and a question that interests me as well. Thanks.
 
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  • #14
ISamson said:
I think OP is referring to "Since they are constants, the definition of constant itself states that a constant is something that doesn't change, how can they change?". I think that is the OP's question and a question that interests me as well. Thanks.

Yes it is. Thank you for correcting it.
 
  • #15
f95toli said:
Note that a bunch of fundamental constants will change (and some will be assigned exact values) later this year when the SI is redefined.
Yes, that was my thought also. The dimensionful fundamental constants are a reflection of our units, not physics. But I am not aware of any change to SI in 1986.
 
  • #16
Serra Nova said:
"The 1986 adjustment of the fundamental constants has implications with respect to the establishment of standards for electrical units".
https://link.springer.com/chapter/10.1007/978-94-009-2955-5_5
That is interesting. I was unaware of this. Unfortunately, I am not so curious that I am willing to purchase the article. Does the article itself not describe the cause of the change?
 
  • #17
ISamson said:
"Since they are constants, the definition of constant itself states that a constant is something that doesn't change, how can they change?". I think that is the OP's question and a question that interests me as well
I don’t know this 1986 revision. However, consider the speed of light. It is 299792458 m/s and it is 6.7E8 mph. Since it is a constant, how can it change?

If this 1986 revision was motivated by a change in the SI, then it is that kind of change. Unfortunately, I don’t know if that is the case.
 
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What are fundamental physical constants?

Fundamental physical constants are numerical values that are considered to be universal and unchanging in nature. They are used to describe the fundamental laws and principles of physics.

How are fundamental physical constants determined?

Fundamental physical constants are determined through experimental measurements and theoretical calculations. Scientists use highly precise instruments to measure these constants and compare the results with other measurements to ensure accuracy.

What is the significance of fundamental physical constants?

Fundamental physical constants are significant because they provide a framework for understanding the physical world and allow scientists to make predictions and calculations with a high degree of accuracy. They also help to unify different areas of physics and provide a basis for developing new theories.

Are fundamental physical constants truly constant?

While fundamental physical constants are considered to be universal and unchanging, there is ongoing research and debate about whether they may have varied over time or in different regions of the universe. However, for practical purposes, they are still considered to be constant and are used in scientific calculations.

How many fundamental physical constants are there?

There are currently 26 fundamental physical constants recognized by the International Committee for Weights and Measures. However, some scientists argue that there may be more constants that have yet to be discovered or accurately measured.

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