B Transforming Relativistic Kinetic Energy: A Concise Mathematical Trick

[quiet]

Hi. I have seen a mathematical trick, which allows us to rewrite relativistic kinetic energy as Newtonian kinetic energy, multiplied by a function. The function is concise. It is not a serial development. If anyone is interested I can copy that trick here.

 

[Ibix]

Relativistic kinetic energy is $(\gamma-1)mc^2$. Newtonian kinetic energy is $mv^2/2$. So the relativistic kinetic energy is $2 (\gamma-1)c^2/v^2$ times the Newtonian kinetic energy. Although this depends on equating Newtonian mass with rest mass, a topic of occasional debate on this forum so there may be a factor of$\gamma$ in there somewhere.

The question is why you'd want to do that. It doesn't reveal any interesting physics as far as I can see. It's just algebra for the sake of it.

 

[quiet]

What does one want to do? In my case to have different ways of looking at an issue, that is, to widen the look.

 

[berkeman]

to widen the look.

What if the other way of looking at it is flawed or doesn't add any value?

 

[quiet]

It is true. That can happen. Only You can judge the uselessness of something like that, in case you get to see it.

 

[berkeman]

It is true. That can happen. Only You can judge the uselessness of something like that, in case you get to see it.

Well, if you do end up posting it, be sure to post a link to a peer-reviewed publication (or mainstream textbook) that also shows it. That it the standard we use at the PF for technical discussions. Thank you.

 

[quiet]

I have not copied the link. Would it be a good idea to remove this thread?

 

[fresh_42]

I have not copied the link. Would it be a good idea to remove this thread?

I locked it, as we usually don't remove threads. But there is still something of information here: As a scientific website, we can ask scientific questions, as "Does anybody know something about the formal connection between ... and ... or is it of any value?" This might - and I'm not saying it does - give rise to an interesting discussion. To state something without any reference or proof is not a scientific method, except it is something more or less obvious. The subject here is more or less obvious, and the question should have been whether it is of any use, and not implicitly assume it is. Also

If anyone is interested I can copy that trick here.

is not a good point to start with. How should your readers know beforehand? And what does "a trick" mean? Tricks normally achieve something, but this is not obvious here and has been rightfully questioned.

Thread closed.