# Wait.... what causes gravity again?

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1. Sep 5, 2015

### 1832vin

last week, i've just gone through and reviewed myself with general relativity, and am confused, but in a good way; but this time, i had spaces to question it

so.... what causes gravity again?
cuz apperently, mass causes gravity, which curves spacetime, but gravity causes mass to exist.....? (microscopically); i'm not adequately familiar with quantum, but if you have a plentiful enough explanation, i might learn it in depth; but...
i thought mass is caused by particles (that are able to) interacts with higgs field, and (through some things), it looses energy, and mass is a result of it (actually, i also want to confirm that if you loose energy, idk where did it came from)
but if mass causes gravity, and gravity causes mass, then it's a positive close loop feedback system, where you'd get constantly increasing mass.....
@_@"
or am i just totally wrong......

2. Sep 5, 2015

### Geofleur

Gravity affects the distribution of mass. It doesn't cause mass. There's a good analogy with electromagnetism here. Charges and currents cause electric and magnetic fields, and these in turn cause currents and charges to re-arrange. In GR, mass tells spacetime how to curve, and curved spacetime tells mass how to move. A gravitational field will not change the intrinsic mass of a particle.

3. Sep 5, 2015

### Drakkith

Staff Emeritus
As Geofleur says, mass causes spacetime to bend, and this bending tells mass how to move within spacetime. More technically, energy (which includes mass) and stress affect the stress-energy tensor which is where gravity comes from.

4. Sep 6, 2015

### Xu Shuang

Gravity is not really real, it's a phenomenon induced by the curvature of space-time, and mass caused the curvature of space-time. Things accelerates down, but they are not really accelerating, they are simply trying to travel in a "strait line" in space-time. But time at above is faster than at below, you know ...

5. Sep 6, 2015

### 1832vin

well, i could have just rephrased it to "what causes curvature of space-time"

6. Sep 6, 2015

### Drakkith

Staff Emeritus
Indeed. The OP asked a specific question about how mass and spacetime curvature work. He did not ask a general, "What is gravity" question. I've already had to delete a post for being off topic. Any further replies should address the OP's specific question, not ramble on about how "Gravity isn't really a force" or some other fact about gravity which doesn't help the OP.

7. Sep 7, 2015

### mraj

earth is a whole system itself .so mass conservation apply always. gravity force can be increase as mass varied. but force's accelerationit always remains constant.
much partical joint makes much force attraction.and mass of earth is constant.

8. Sep 9, 2015

### UncertaintyAjay

By intrinsic mass, I suppose you mean rest mass right? because if the gravitational field gets something to move, its relativistic mass will increase. Just clarifying because I'm new to relativity.

9. Sep 9, 2015

### Geofleur

Yes, I did mean the rest mass.