# What equations are affected by Lorentz Transformations

Many equations are affected by Lorentz transformations. Time, mass, volume of a moving object, momentum, force etc. I want to know if the following equations are affected by Lorentz transformations:

1. Distance=velocity*time (r=vt)
2. E=hv
3. j*=ot
4. F=G*m1*m2/r^2

Also, is the Newton's Theory of Universal gravitation affected by General Relativity?

## Answers and Replies

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Pengwuino
Gold Member
I'm not sure what your third equation is but the first one is obviously changed as the time is modified. The second one, I assume you mean $E = \hbar \omega$ which is also modified because the angular frequency is modified. This causes red/blue-shifts. Newton's law of gravitation is modified as well because of the length contraction.

However, Lorentz transformations are a feature of special relativity. General relativity is not so simple.

jtbell
Mentor
Also, is the Newton's Theory of Universal gravitation affected by General Relativity?
General Relativity replaces Newton's theory of gravitation.

bcrowell
Staff Emeritus
Gold Member
I think Pengwuino's analysis is correct as far as chages in the values of the variables. But if the OP intended to ask about changes in the forms of the equations, then the form of 1 and 2 is frame-invariant.

I'm not sure what your third equation is...
Oops. I meant it to be j*=ot^4 where j* is the power radiated and o is sigma, the stefan's constant.

However, Lorentz transformations are a feature of special relativity. General relativity is not so simple.
So $$F=G\frac{{m}_{1}{m}_{2}}{{r}^{2}}$$ is changed in General Relativty also?

...the first one is obviously changed as the time is modified. The second one, I assume you mean $E = \hbar \omega$ which is also modified because the angular frequency is modified. This causes red/blue-shifts. Newton's law of gravitation is modified as well because of the length contraction.
Thanks.

General Relativity replaces Newton's theory of gravitation.
So, $$F=G\frac{{m}_{1}{m}_{2}}{{r}^{2}}$$ is changed in General Relativty?

Last edited:
Pengwuino
Gold Member
So, $$F=G\frac{{m}_{1}{m}_{2}}{{r}^{2}}$$ is changed in General Relativty?
Yes, it no longer makes sense to speak of forces in GR.

Yes, it no longer makes sense to speak of forces in GR.
But in modern physics, string theory does talk about gravity as a force, right? And in string theory,

$$F=G\frac{{m}_{1}{m}_{2}}{{r}^{2}}$$

is still correct right?

Pengwuino
Gold Member
But in modern physics, string theory does talk about gravity as a force, right? And in string theory,

$$F=G\frac{{m}_{1}{m}_{2}}{{r}^{2}}$$

is still correct right?
No it isn't.

bcrowell
Staff Emeritus
Gold Member
Dimension10, relativity isn't just a matter of putting fudge factors in equations. If you want to learn some relativity, some good books are (from easiest to hardest):

Takeuchi, An Illustrated Guide to Relativity
Mermin, It's About Time: Understanding Einstein's Relativity
Taylor and Wheeler, Spacetime Physics

Dimension10, relativity isn't just a matter of putting fudge factors in equations. If you want to learn some relativity, some good books are (from easiest to hardest):

Takeuchi, An Illustrated Guide to Relativity
Mermin, It's About Time: Understanding Einstein's Relativity
Taylor and Wheeler, Spacetime Physics
Thanks. I have also read the paper itself but I can't really find his equation for the Gravitational force...

bcrowell
Staff Emeritus