Physics / Maths class - ask a professor... or someone who thinks he is one :p

[smartquin]

Ok, I did some calculus and I know kinematics etc. but I'm trying to get the concept of tensors (Ricci/stress energy etc.) to understand the einstein field equation. Can someone help me understand this? I did basic matrices and some vector stuff, but I still don't quite get it. Someone please help!

PS- If anyone else has questions about maths/science, post your questions

[smartquin]

It seems that there isnt anyone with questions, and no-one with answers...

[Qasim]

Online course - http://vishnu.mth.uct.ac.za/omei/gr/

[Zardak]

LoL, i dont think i am that advanced. you seem way ahead of me.

[Zekk]

This thread is weird....I must be lost

[smartquin]

Online course - http://vishnu.mth.uct.ac.za/omei/gr/

Thanks

[TechnoWraith]

This thread is weird....I must be lost

This thread is a place to ask physics/science related questions and seeing if others can help answer those questions. I'm guessing most of the question might be homework related. Otherwise, questions may be curiosity seekers trying to find answers to their own questions.

[Zekk]

Ok then....umm Im not in phisics yet *Walks away feeling dumb*

[smartquin]

Ok, new question, if a photon has zero mass, but has energy, how can it not have mass? E=mc^2 doesn't apply for photons?

[TechnoWraith]

Ok, new question, if a photon has zero mass, but has energy, how can it not have mass? E=mc^2 doesn't apply for photons?

Maybe the photon ate the mass to make it's energy?

[Zekk]

^ makes sense

[smartquin]

Maybe the photon ate the mass to make it's energy?

stupid photons, why dont they share? always thinking of themselves....

[TechnoWraith]

stupid photons, why dont they share? always thinking of themselves....

Ask the photon.

[smartquin]

But every time I go to talk to a photon, all his buddies come and blind me... its a conspiracy....

Anyway, bak to reality, I rekon that photons either have a small mass, or are made of 2 particles/waves, one with a positive mass, one with a negative mass (so the net mass is 0), and the energy is E=abs(mc^2).

[Lord §okar]

Ok, new question, if a photon has zero mass, but has energy, how can it not have mass?
A photon doesn't have energy, it is energy, it therefore has no mass.

E=mc^2 doesn't apply for photons?
That formula defines the relationship, and proportionality, between energy-mass conversions, it has really no relevance here.

Anyway, bak to reality, I rekon that photons either have a small mass,
Nope.

or are made of 2 particles/waves, one with a positive mass, one with a negative mass (so the net mass is 0), and the energy is E=abs(mc^2).
No, such a particle wouldn't differ from one that has zero mass at any rate.