What makes gravity, gravity?

[iNow]

What's the point of devising a particle for anything and everything when GR explains it just fine?

 

But it doesn't. GR is just another approximation that doesn't hold in all cases.

[Bluesky99]

as I think...besides the mass of the planet no matter where you are.

The self-rotation will make the same force just like the gravity.

Image that you are in the universe, and there is a out-space station...how to keep human walk in it? well, self-rotation can solve the problem

 

p.s I'm not from a country that English is my mother language, and this is my

first time try to post something on...so, if you can't understand waht am

I talking about, I'm so sorry and I will improve it. Thanks for your

understanding.

[Klaynos]

I don't see how QM even makes a case. What's the point of devising a particle for anything and everything when GR explains it just fine?

 

Blackholes, GR predicts a singularity. This is NOT GOOD!!!!!!!!!!!!!!!!!!!!!!!!!

 

Physicist do not like 0's they are not physical...

 

And we like the idea of unifying forces... God ol' Maxwell for thinking that one up!

[Realitycheck]

This is the part where GR calculates a center of gravity, even though there is 9.9 10^99 gigatonnes of atomic shrapnel piled up and in the way of the singularity, right? I remember that I actually liked Maxwell. He's the one that said that particles are for sweeping off your floor, right?

[thedarkshade]

Im not too sure how to word this so hang with me

 

Well, my year. 8 science teacher is not the brightest bulb in the box, but he absouloutly stumped me with a question today; "Why is gravity there?". Is there even an answer for this? If I dont get a good answer by monday I have a lunch time clean up (long story). Am I crazy or is that an impossible task to set (especially for an 8th grader).

I'd go with post #2! You could refer to gravity using the classical newtonian formula:

 

[math]F=G\frac{m_1m_2}{r^2}[/math]

 

You can refer to gravity as a force that acts between any to objects and is directly depended from their mass and indirectly from the distance. That means the heavier the mass, the higher gravitational attraction, the larger the distance the smaller the gravitational attraction. But what gravity actually is I personally think is kinda mysterious.

 

Another explanation would be that gravity turns out to disortions in space-time fabric...

[Royston]

This is the part where GR calculates a center of gravity, even though there is 9.9 10^99 gigatonnes of atomic shrapnel piled up and in the way of the singularity, right?

 

No, this is where GR fails, when you approach high energy and compact regions of space-time (the interior of black holes) the maths run into infinities...or indefinites. I'm not qualified to explain it mathematically, but a singularity is a mathematical term, nothing more.

 

http://www.scienceforums.net/forum/showthread.php?t=28271&page=2

 

see post 23 for a good explanation

 

I remember that I actually liked Maxwell. He's the one that said that particles are for sweeping off your floor, right?

 

The Maxwell equations which lead to relativity (amongst other things) are continuous, i.e they are field equations that are not built on quanta, the field is infinitely divisible, QM rectifies this, hence relativity as iNow suggested is just an approximation of the true picture, or are you going to argue that discrete particles which have been observed do not exist ? (see bold)

 

Look up QED, and agentchange please use the search function, all your recent questions have been covered more than a few times.

[Realitycheck]

I was just trying to make a joke out of Maxwell's definition of light, without particles, and stretched it out a bit too far. Did they even know about particles back then? I will try and restrain myself and get more up to speed on my QED.

[Royston]

I was just trying to make a joke out of Maxwell's definition of light, without particles, and stretched it out a bit too far.

 

My bad, FYI the Maxwell equations set a limit on the speed of light, hence Einsteins interest.

 

Did they even know about particles back then?

 

It was a controversial subject at the time. IIRC even Planck didn't believe in atoms.

 

I will try and restrain myself and get more up to speed on my QED.

 

You've asked good questions, but they've been asked before ten fold, that's all.

[Mr.Chockuls]

i think this post should be in physics, the gravity

[swansont]

i think this post should be in physics, the gravity

 

I didn't even notice that it wasn't. Moved.

[Riogho]

Anotherother fun questions that a lot of teachers wont the awnsers to is: "If I shake this string then I get a wave of string but, what is light a wave of?", the awnser is that it isn't. Which really amuses me for some reason.

 

A wave of the electromagnetic field