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-3
votes
1answer
52 views

Why $\epsilon_0 = 1/(4\pi k)$ instead of $\epsilon_0 = 4\pi k$? [on hold]

In my physics book, they consider a positive point charge $q$ and a spherical surface of radius $r$ centered on this positive charge. Then the flux through this surface is given by $$\Phi = \iint \vec{...
1
vote
0answers
44 views

How Higgs Field is a constant in an Expanding Universe [on hold]

Going through information on Higgs Field in various forums, it seems that the mass of an object is due its interaction with the Higgs Field which is constant throughout the universe. However it ...
3
votes
1answer
50 views

Would order 1AU metric expansion of space begin if the solar system were not inside a galaxy?

In this question I describe the >30 years of laser ranging between lasers on Earth and the retroreflector arrays on the Moon. Amazingly, after comparing this data to simulation of all of the orbital ...
8
votes
4answers
1k views

Can the accuracy in Planck's constant ever be increased?

I guess I am having some confusion about the history of calculating Planck's constant. I see the mass of the electron may come into the equation here but isn't the measurement of mass based mostly ...
29
votes
6answers
4k views

Does the speed of light in vacuum define the universal speed limit?

Is light the thing causing the universal speed limit to be $299\,792\,458\,\mathrm{m/s}$? So the universal speed limit would be different if light travelled faster or slower? Or, is $299\,792\,458\,\...
1
vote
2answers
64 views

What is the difference between a physical constant, a scalar, and a conserved quantity

I don't really know how to properly articulate this question. This question popped into my mind when pondering why the fact that a physical constant like the speed of light doesn't have an associated ...
3
votes
1answer
42 views

Running Constant Values At Very Low Temperatures

From Wikipedia Coupling Constants, using QED as an example. I realise that the one-loop beta function in quantum chromodynamics is negative. If a beta function is positive, the corresponding ...
-3
votes
0answers
36 views
0
votes
1answer
52 views

Are there any numerical predictions of the Newtonian gravitational constant $G$ from modern theories?

There are no established relationships between the Newtonian gravitational constant $G$ and other fundamental constants, so there is no way to derive its value from other quantities. Its value must be ...
0
votes
0answers
45 views

Fine Structure and Fine Structure Constant - intuitive relation?

How does the fine structure and fine structure constant relate to each other, intuitively? I've seen $\alpha$ extrapolated as a term in energy calculations for fine structure, but is there a ...
-1
votes
2answers
114 views

Do we have a better approximation of $c$ than 299792458 m/s? [duplicate]

All sites give this value as "exact" value. I mean, what's after the comma? 299792458,000 m/s?
4
votes
2answers
99 views

If maximum speed limit $c$ is made infinite, will general theory of relativity become equivalent to Newton's gravitational theory?

We know that special relativity tends to become equivalent to classical theory of relativity as the speed limit of nature becomes infinite. If this happens, clock will tick at the same rate ...
-6
votes
1answer
99 views

Must the fine structure constant be an irrational number? [closed]

This question concerns a conjecture on the nature of $\alpha = e^2/4\pi\epsilon\hbar c$ in light of black hole holes. Let me consider the Reissnor-Nordstrom metric for a charged black hole $$ ds^2 = \...
0
votes
2answers
192 views

Is it possible for the Higgs Field strength, to increase with time? [closed]

Magnetic fields are created when an electric current flows: the greater the current, the stronger the magnetic field. What influences could affect the Higgs Field? If the Higgs field grew in ...
0
votes
4answers
99 views

Is there an official list of independent units of measurements?

When I say 'independent units', I mean those which cannot be broken down anymore, and simultaneously forms the basis for any more, complex measurements. For example, height, length, and width can all ...
0
votes
0answers
54 views

Why Newton's gravitational constant remains unchanged in relativity though gravity is not a force?

I know that Einstein described gravity as a curvature of spacetime. So, It is not a "force" but why Einstein had to accept Newton's gravitational force constant?
6
votes
1answer
279 views

Why is the gravitational constant so difficult to measure?

The gravitational constant seems to be very low precision. For example, in the Wikipedia article recent measurements are given as having the significands of 6.67 and 6.69, a difference of 2 parts in ...
-4
votes
1answer
97 views

When can the constant of proportionality in an eq be set equal to 1 and when not? [duplicate]

In $F=kma$, $k=1$ but in $F=kx$, $k$ is not equal to 1?So what are the conditions for the constant of proportionality to be set 1?
2
votes
2answers
149 views

The mass of the proton times its charge radius is very close to 4ħ/c. Is this a coincidence?

The claim is $r_p m_p = 4 L_0 M_0 = 4\hbar/c$, where $r_p$ and $m_p$ are the proton's charge radius and mass, and $L_0$ and $M_0$ are the Planck length and mass. Using the muon measurement $r_p=0....
1
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0answers
40 views

Are there characteristics that distinguish our universe?

Are there any defining characteristics of our universe that could be different for other universes (or "instances of our universe") that operate under the same laws of physics? And which, if any, are ...
0
votes
2answers
60 views

Proper units for physical quantities when $\hbar$=$1$

How to deal with the units of quantities if $\hbar=\tfrac{h}{2\pi}=1$? For example, the energy $E=\hbar\omega$: If I have chosen $\hbar=1$, how do I use the units to properly differentiate between ...
2
votes
0answers
38 views

Any method to determine the gravitational constant $G$ from observations in cosmological scale?

By the observations in cosmological scale, I mean observations by astrophysicists like motions of quasars in far distance from us, relative motions of our galaxy to others, etc. I know the famous ...
3
votes
1answer
57 views

How is a result of no time variation in the gravitational constant $G$ related to a measurement of no local expansion?

In this answer @PhillS linked to the paper Progress in Lunar Laser Ranging Tests of Relativistic Gravity which has given me a great start. While its main focus is on the Equivalence Principle (EP) ...
1
vote
1answer
173 views

Difference between theoretical equations and empirical equations

Some equations are theoretical in the sense that they are derived from an underlying theory. Other equations are empirical in the sense that they were selected only because they fit experimental data ...
7
votes
3answers
101 views

Are dimensionless physical constants predicted to be rational, irrational, or transcendental numbers?

Are dimensionless physical constants predicted to be rational, irrational, or transcendental numbers? Directly measured ones are obviously unknown, but according to Wikipedia many dimensionless ...
2
votes
3answers
495 views

Why do we need constants? [closed]

This question is driving me crazy because I cannot find a straightforward answer. I want to know what a physical constant exactly is. I know that it’s a value that doesn’t change, but what is it? Why ...
5
votes
1answer
106 views

Proportionality Constant in Einstein Field Equations

The Einstein Field Equations: $$G_{ab}~=~8\pi T_{ab}.$$ I am familiar with how to obtain the $8\pi$ proportionality factor through correspondence with Newtonian gravity, but am wondering if this ...
0
votes
3answers
174 views

Why did Einstein took speed of light unit or constant in his equation of relativity?

We can find that no object can have speed more than light from Einstein's equation of relativity because if anything have speed more than light then we get -ve value within square root. But why did ...
1
vote
1answer
69 views

About Planck tension in strings theory as stated in “The Elegant Universe”

In the book "The Elegant Universe" by Brian B. Greene, on chapter 6 it is stated that there's the so called "Planck tension" in string theory, and it is given a value of $10^{39}$ tons. This value is ...
2
votes
0answers
26 views

Do time/location-dependent fundamental constant exists? [closed]

Throughout history people have been carrying out experiment after experiment to test many of the known constant, so I like to know if there are any oddities among the known fundamental constants. If ...
-1
votes
1answer
68 views

Which was the first Coulomb's constant value? [closed]

Which was the first Coulomb's constant value? I didn't found any info in the Internet. I need the first value of K to compare it with my experiment. Could you please help me?
1
vote
0answers
35 views

Where does the square root of two in the conversion between the Fermi constant and the weak coupling constant come from?

As in the title, where does the square root of two in the conversion $$ G_{F}=\frac{\sqrt{2}g^{2}}{8m_{W}^{2}} $$ between the Fermi constant and the weak coupling constant come from? I was able to ...
0
votes
3answers
69 views

What does the $k_e$ in Coulomb's law and $G$ in Newton's Universal Gravitation Law mean?

I very well understand the proportionality relation that was used to derive these laws like $F$ is proportional to product of masses and inversely to radius squared and hence its proportional to the ...
1
vote
1answer
29 views

How are the constants in hydraulics calculated? [closed]

I would like to know (out of sheer morbid curiosity) how constants in hydraulics are calculated. The constants are, for good ol' 'Merican units; 63025, 5252,and 231. These constants came out of "...
1
vote
1answer
80 views

Can the value of $c$ be calculated from Relativity? [duplicate]

I have three related questions about what theories or equations can calculate and what is an input parameter/constant to the theories. This question is not about parameter units (as another similar ...
5
votes
2answers
139 views

String models of particle physics

What general features of particle physics are derived/replicated by constructing string models of particle models? How do such models address the fixing of free parameters like the masses and the ...
3
votes
2answers
73 views

Does the speed of light change? [duplicate]

I know that there is a similar questions, but I think mine is a bit different. I wonder if with the expansion of the universe the speed of light changes. It seems that the speed of light is very ...
2
votes
2answers
104 views

Why is the speed of light exactly $299,792.458$ m/s and not faster or slower? [duplicate]

Why is the speed of light $299,792,458$ metres per second, and not faster or slower. Why not $500$ trillion kilometers per second or $120$ miles per hour? This has been 'bothering' me for a while. ...
3
votes
1answer
56 views

Why are physical “constants” constant?

I am really sorry if this question is inappropriate or wrong. But this is something that I can never perfectly agree with, it just keeps on striking my mind when I am studying something new in Physics....
1
vote
0answers
58 views

What's the unit of fine-structure constant? [closed]

What's the unit of fine-structure constant? I mean in SI units.
2
votes
0answers
44 views

Can we alter/engineer natural “constants”? [closed]

There are numerous constants that define the physical universe, from the fine structure constant to Planck to the speed of light etc. Can any of these be altered locally? For example, it seems that ...
1
vote
2answers
129 views

Is there an equivalent of the Planck length for time?

Is there an equivalent of the Planck length for time? I'd just like a term I may use (high-level) for a similar "unit of time"? I am not looking for a debate on how discrete time might be, but if ...
15
votes
5answers
623 views

Is the Boltzmann constant really that important?

I read a book in which one chapter gave a speech about the fundamental constants of the Universe, and I remember it stated this: If the mass of an electron, the Planck constant, the speed of light,...
-2
votes
1answer
79 views

Constancy of speed of light in vacuum? [closed]

Have scientists tried their best to calculate speed of light in vacuum? It seems very absurd to me that light of all frequencies have same velocity in space. Can someone find in future if this speed ...
1
vote
1answer
88 views

if there is Ideal Gas constant, then do we have real gas constant?

We have Ideal gas constant for ideal gases. But ideal gas is very hard to make or to be found. So we have real gases in nature. Now there is 'real gas equation' (also called 'Van Der Waal's equation') ...
1
vote
5answers
170 views

What in nature causes Newton's gravitation constant to have its given value?

Does the value of Newton's universal gravitational constant $G$ remain a mystery? Why does it have the value that it has?
0
votes
0answers
76 views

Does rest mass increase in the FRW metric?

The flat FRW metric can be written in conformal co-ordinates: $$ds^2=a^2(\eta)(d\eta^2-dx^2-dy^2-dz^2)$$ where $\eta$ is conformal time. Let us assume that $a(\eta_0)=1$ when $\eta_0$ is the present ...
2
votes
1answer
352 views

Is there a relationship between the Cosmological constant and the Hubble constant?

I looked around to see if this precise question was asked before and it appears not to be. So is it just me or has anyone else noticed that, no matter what consistent set of units you use, $$ \...
1
vote
3answers
349 views

Why do we obtain classical physics by taking the limit of Planck's constant to zero?

Why if we specifically set Planck's constant equal to zero (the limit of it) do we sometimes get classical physics? I mean, what does it mean physically to set the constant equal to zero? Or to say it ...
-2
votes
1answer
255 views

Gravitational constant, $G$, What if it is not Constant?

The question is on title; What if Gravitational Constant, $G$, is not constant? Let's skip all the local consequences if it would suddenly change, like asked here; Can gravitational constant be ...