# What equations are affected by Lorentz Transformations

1. Jun 22, 2011

### dimension10

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?

2. Jun 22, 2011

### Pengwuino

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.

3. Jun 22, 2011

### Staff: Mentor

General Relativity replaces Newton's theory of gravitation.

4. Jun 22, 2011

### bcrowell

Staff Emeritus
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.

5. Jun 22, 2011

### dimension10

Oops. I meant it to be j*=ot^4 where j* is the power radiated and o is sigma, the stefan's constant.

So $$F=G\frac{{m}_{1}{m}_{2}}{{r}^{2}}$$ is changed in General Relativty also?

Thanks.

So, $$F=G\frac{{m}_{1}{m}_{2}}{{r}^{2}}$$ is changed in General Relativty?

Last edited: Jun 22, 2011
6. Jun 23, 2011

### Pengwuino

Yes, it no longer makes sense to speak of forces in GR.

7. Jun 23, 2011

### dimension10

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?

8. Jun 23, 2011

### Pengwuino

No it isn't.

9. Jun 23, 2011

### bcrowell

Staff Emeritus
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

10. Jun 23, 2011

### dimension10

Thanks. I have also read the paper itself but I can't really find his equation for the Gravitational force...

11. Jun 23, 2011

### bcrowell

Staff Emeritus
What paper are you referring to? There is no relativistic equation for gravitational force, because gravity isn't described as a force in relativity.

12. Jun 23, 2011

### WannabeNewton

Are you maybe talking about an equation describing tidal gravitational forces?