Linked Questions

37
votes
8answers
6k views

What is the proof that the universal constants ($G$, $\hbar$, $\ldots$) are really constant in time and space?

Cavendish measured the gravitation constant $G$, but actually he measured that constant on the Earth. What’s the proof that the value of the gravitation constant if measured on Neptune would remain ...
26
votes
6answers
7k views

Do the laws of physics evolve?

Hubble's constant $a(t)$ appears to be changing over time. The fine stucture constant $\alpha$, like many others in QFT, is a running constant that varies, proportional to energy being used to measure ...
8
votes
3answers
691 views

Why does the fine-structure constant $α$ have the value it does?

This is a follow-up to this great answer. All of the other related questions have answers explaining how units come into play when measuring "universal" constants, like the value of the speed of ...
5
votes
2answers
1k views

Is the fine structure constant actually a constant or does its value depend on the energy scale?

The value of the fine structure constant is given as $$ \alpha = \frac{e^2}{4\pi\varepsilon_0\hbar c} = \frac{1}{137.035\,999..} $$ It's value is only dependent on physical constants (the elementary ...
7
votes
4answers
1k views

Can the cosmological constant change with time?

This post is a specialization of the post: Can the proportion of dark energy change? Can the cosmological constant change with time? If so, is there a measurement of this evolution up to now, and ...
5
votes
1answer
720 views

The fine structure constant - can it genuinely be a random variable?

The question Does it make sense, and are there physical reasons to think about the fine structure constant as a (very concentrated) probability distribution rather than a single real number? ...
3
votes
2answers
423 views

Was Planck's constant $h$ the same when the Big Bang happened as it is today?

Was Planck's constant $h$ the same when the Big Bang happened as it is today? Planck's constant : $$h= 6.626068 × 10^{-34}\, m^2 kg / s,$$ $$E=n.h.\nu,$$ $$\epsilon=h.\nu$$
0
votes
1answer
313 views

Big bang red shift verification

So I have read on proofs for the Big Bang theory as it appears to be a bit far-fetched to me (the layman). I mean, definitely there is some genius mathematics behind the fancy yet inaccurate ...
3
votes
1answer
269 views

If Fine Structure Constant in not uniform in space what would that imply for cosmic background?

Recently J.Webb submitted paper which has extraordinary claim - that Fine Structure Constant is different in different directions in space! He (with others) measured $\alpha$ using quasar spectrum ...
2
votes
1answer
109 views

Do we regularly measure and update our physical constants (By using the LHC)?

This question is motivated by sheer curiosity. I certainly do not expect that the free parameters we use in the standard model have changed in value since we started measuring them with a "modern" ...
1
vote
0answers
72 views

How does the fine-structure constant $\alpha$ vary on cosmological scales?

The observations of quasar absorption spectra show that the fine-structure constant varies on large scales. I know that $U(1)_{EM}$ coupling constant $\alpha$ depends upon the coupling constants of $...
1
vote
0answers
50 views

Expansion of the universe & laws of physics [duplicate]

Does the expansion of the universe have an effect on the laws of physics, or the constants used in physics? If we were to imagine the universe 40 billion years later, would the same laws still apply?