The physical-constants tag has no wiki summary.
9
votes
1answer
96 views
Is the fine-structure constant a parameter of the standard model?
According to the wikipedia entry on the fine-structure constant:
In fact, α is one of the about 20 empirical parameters in the Standard Model of particle physics, whose value is not determined ...
1
vote
0answers
30 views
Contact electricity and photoelectric effect
Most universities provide an experiment about the photoelectric effect to determine $h$ by measuring the stop voltage against the light frequency and calculating the slope $h/e$.
But mostly they also ...
0
votes
1answer
66 views
Why Planck scale is so important?
I know that Planck scale is the scale where both, gravity and quantum effects are relevant simultaneously. Are there more reasons?
-4
votes
1answer
80 views
Describing physical constants in alternate wording; c = there can only be 671million miles of space for every second of time [closed]
This spawns from part of an answer to a question I asked.
All sorts of things go to 0 and/or ∞ if you start boosting at c, and
so you cannot boost into and out of a photon's frame.
It ...
0
votes
1answer
49 views
Zero uncertainty constant and a unit change
So, we know the speed of light with zero uncertainty. We also know that values of $\epsilon_0$ (electric constant) and $\mu_0$ (magnetic constant) are known with zero uncertainty.
My questions are ...
0
votes
0answers
62 views
Why there can't be infinitely small existing?
Why there can't be infinitely small existing?
I am not suggesting it can or cannot. I am asking can there be an absolute or reasonable answer to that question.
1
vote
1answer
67 views
What is the smallest existing thing in theory and law?
What is the smallest existing thing in theory and law?
5
votes
2answers
78 views
What constant varies in the fine structure constant?
Using the renormalization group approach, coupling constants are "running". If we apply this to the fine structure (coupling) constant, we do know that, e.g., at energies around the Z mass, $$\alpha ...
1
vote
1answer
29 views
measure higher frequencies then half of Planck-frequency?
The maximum frequency is defined by the Planck frequency $\omega_P$. Also there is the Shannon theorem which tells us that to lossless capture a signal, you have to sample it with minimum of the ...
9
votes
5answers
959 views
How to get Planck length
I know that what Planck length equals to.
The first question is, how do you get the formula
$$\ell_P~=~\sqrt\frac{\hbar G}{c^3}$$ that describes the Planck length?
The second question is, will any ...
7
votes
0answers
103 views
Why is the Planck length the shortest measurable length? [duplicate]
I quote from the Wikipedia article on Planck length:
According to the generalized uncertainty principle, the Planck length
is in principle, within a factor of order unity, the shortest
...
6
votes
2answers
209 views
Is there an explanation for the 3:2:1 ratio between the electron, up and down quark electric charges?
I understand that the NNG formula relates $Q$, $I_3$, and $Y$ and can be derived in QCD; does this unambiguously predict the electric charge ratios without making assumptions about the definitions of ...
3
votes
1answer
78 views
Units for physical constants
Someone told me that units for $G$ and $\epsilon_0$ (gravitational constant and Coulomb's constant) are placed there simply to make equations work dimensionally and that there is no real physical ...
10
votes
6answers
850 views
What's keeping us from simply redefining Avogadro's Number / the Mole as a definite integer?
This might be a question to ask in a Chemistry site, but because there is a lot of talk about redefining many units of measurements in terms of Avogadro's Number / the Mole, I was wondering why we ...
2
votes
3answers
71 views
Curious relation between the dependance in ℏ of Planck units and units dimensions
Looking at Planck units, there seems to be a curious rule between the dependance in $\hbar$ of a Planck unit and the unit dimensions of the corresponding physical quantity.
Let the dimensions of the ...
0
votes
0answers
64 views
Has unnaturalness motivated new ideas in physics?
The cosmological constant problem arises because the natural scale of the cosmological constant is $10^{120}$ times larger than what we observe. This implies that the dimensionless constant is much ...
5
votes
7answers
876 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 ...
2
votes
1answer
213 views
What really is Planck's constant and what are its origins?
In the physics texts I have read and other info online, they says Planck's constant is the quantum of action or that it is a constant of the ratio of the energy of a particle to its frequency. Im ...
9
votes
4answers
571 views
Why does the speed of light $c$ have the value it does?
Why does light have the speed it does? why is it not considerably faster or slower than it is? I can't imagine science, being what it is, not pursuing a rational scientific explanation for the speed ...
-5
votes
1answer
129 views
Where the fine structure constant $\alpha$ is speed parameter of electron $\beta_e$, How can it be a constant?
The fine structure constant $\alpha$ actually is speed parameter of electron $\beta_e$, moving around proton in hydrogen atom.
$v_n=\frac {\alpha_c}{n}=c\frac {\alpha}{n}=c\frac {\beta_e}{n}$
How ...
-1
votes
1answer
103 views
Hubble Constant and Planck Constant
Has there been any effort to understand Hubble's limit as a quantum phenomenon?
It seems like they are suggesting the same thing.
12
votes
5answers
911 views
How can the speed of light be a dimensionless constant?
This is a quote from the book A first course in general relativity by Schutz:
What we shall now do is adopt a new unit for time, the meter. One meter of time is the time it takes light to travel ...
-4
votes
1answer
101 views
How do I publish a physical constant [closed]
I think what i've found is a physical constant that is a physical quantity, universal in nature and constant in time.
but It contrasted with a mathematical constant, which is a fixed mathematical ...
0
votes
0answers
108 views
How many physical constants should there be?
I see there are different accounts on the number of physical constants. Is there any theory predicting what the number of physical constants is? I agree there should be at least one but I have no ...
6
votes
4answers
257 views
Cases of any known fundamental physical constants changing within our locality?
Has there been any cases where the only explanation has been that at least one of the physical constants must have changed to explain an experiment/event/obervation? I am not intrested in large scale ...
6
votes
3answers
195 views
Is there a simple way to compute some physical constant from Feynman diagram statistics?
I've been playing around writing some software to generate Feynman diagrams for QED, respecting the vertex "rules" described here, and avoiding creating isomorphic duplicates.
So from a starter ...
31
votes
4answers
2k views
Dimensionless Constants in Physics
Forgive me if this topic is too much in the realm of philosophy. John Baez has an interesting perspective on the relative importance of dimensionless constants, which he calls fundamental like alpha, ...
4
votes
3answers
2k views
Have I discovered how to calculate the proton's mass using only integers?
Could it be possible that the mass of the proton can be calculated by a series of integer sequences? Or is this just a curiosity?
$$\sum_{m=1}^{\infty } \frac{1}{10^{26}(m^2+1)_{2m}}=$$
...
3
votes
5answers
193 views
Is the gravitational constant $G$ a fundamental universal constant?
Is the gravitational constant $G$ a fundamental universal constant like Planck constant $h$ and the speed of light $c$?
5
votes
1answer
127 views
Definition of Fine-Tuning
I've looked in and out the forum, and found no precise definition of the meaning of fine-tuning in physics.
QUESTION
Is it possible to give a precise definition of fine-tuning?
Of course, I guess ...
0
votes
0answers
40 views
Viscoelastic materials parameters values
I am taking part of a theoretical research about viscoelastic material, in particular related to the Kelvin-Voigt model.
For some numerical simulation we need the values of the Lamé elastic and ...
0
votes
1answer
104 views
How is charge measured and mass of the electron at the same time?
There are few constants that usually come together, $e/m$ also $h/e$. How are they decoupled?
If the speed of light is "derived" as Wikipedia states how meter defined and time?
2
votes
3answers
274 views
Planck time, distance, mass? Why do we take those values?
Say we want to make an educated guess for critical values of time, distance and mass, where quantum gravity effects are supposed to be non-negligible. These values are given the prefix "Planck-". Now, ...
4
votes
2answers
179 views
why there is no accuracy of the measured value of $G$?
With the advancement of Modern Technology still there is no accuracy of the measured value of $G$ Gravitational Constant, why!?
3
votes
1answer
104 views
Official definition of astronomical units
As it is relatively easy to find an official value for a large number of physical constants, (thanks to CODATA), it is not so easy for some units widely used in astronomy (Wikipedia, Google and IAU ...
6
votes
1answer
641 views
Has the speed of light changed over time?
Could someone judge my (stoner) hypothesis that the speed of light has changed over time -- ie. as the universe has expanded in volume light has slowed down, perhaps going so far as back to the big ...
2
votes
2answers
177 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$$
1
vote
3answers
272 views
What is the reason behind specific values for charge of electrons, protons?
Why do things like protons and neutrons have specific values. Also speed of light is a speed in which even if you go towards it, the speed does not vary. But why does light have to travel at speed?
0
votes
1answer
75 views
In what subfields and how fare can the “naive limit” of special relativity be carried?
Even if many interesting similarities between the classical and the quantum mechanical framework have been worked out, e.g. in the subject of deformation quantization, in general, there are some ...
0
votes
2answers
66 views
Why is the thomson cross section constant over cosmological time?
In all astrophysical calculations I'm aware of, the thomson cross-section (for electron scattering) is taken as a constant in time, why is this the case? I have only weak experience in cosmology and ...
3
votes
1answer
133 views
Were the physical constants chosen randomly by the nature?
Were the physical constants chosen randomly by the nature or it was determined by some source of… matter(?).
I really don't have idea. If you could help me it'd be awesome.
12
votes
4answers
750 views
Is the Avogadro's constant equal to one?
Question: Is the Avogadro's constant equal to one?
I was tasked with creating a presentation on Avogadro's work, and this is the first time I actually got introduced to the ...
2
votes
3answers
287 views
What are the physycal meaning of universal constants such as the magnetic, electric and gravitational constants?
I know that:
$G=6.67300 × 10^{-11}\dfrac{Nm^2}{kg^2}$(Gravitational constant)
$K_e=9×10^9\dfrac{Nm^2}{C^2}$(Electric constant or Coloumb's constant)
$k_m=1×10^{-7}\dfrac{Ns^2}{C^2}$(Magnetic constant)
...
2
votes
1answer
118 views
Fine Tuned Universe
Is the fine tuning that cosmologists talk about (that our Universe is fine tuned for intelligent life) is the same as the fine tuning of the squared mass parameter of the Higgs in the Standard Model? ...
0
votes
1answer
95 views
How can constants… change?
I recently noticed that the value of Planck's constant has changed on Wikipedia. The value that I had in mind (from Google), $6.626068\cdot{}10^{-34}\text{J.s}$, has changed to ...
4
votes
5answers
482 views
Why are $\mu_0$ and $\epsilon_0$, which appear in electrostatics and magnetostatics, related to the speed of light which appears in electrodynamics?
$\epsilon_0$ and $\mu_0$ appear in electrostatics and magnetostatics. When we include time varying fields we have electrodynamics and the appearance of c which turns out to be related to $\epsilon_0$ ...
3
votes
1answer
97 views
The fine structure non-constant
If the fine structure constant is different in different parts of the universe, then what would happen if we travelled to those regions?
(I realise this is completely impossible as they are ...
1
vote
2answers
173 views
The time component is $\gamma m c$, so shouldn't $E=mc$?
Basically, the book is Brian Cox's Why Does $E=mc^2$?: (And Why Should We Care?).
I just finished Chapter 5, where we derived the spacetime momentum vector (energy-momentum four vector, as he ...
2
votes
3answers
165 views
What widely recognized organizations set standards used by physics?
I recently answered a question about the meaning of the word "dimension" as used in physics. In that response, I provided the definition given in the International Vocabulary of Metrology (VIM) and ...
5
votes
1answer
431 views
Why can you remove the gravitational constant from a computer game simulation?
I've seen in a few gravity simulation games (ie. bouncing balls) the equation:
force = G * m1 * m2 / distance^2
shortened to this by removing the gravitational ...
