# Does theory of expansion effect gravity?

1. Jul 22, 2015

### Shankar Dev

If space will be expansion then it effect on earth diameter. If earth become narrow then how gravity force work ?

2. Jul 22, 2015

### Staff: Mentor

The expansion of space does not affect objects which are bound together through gravity or one of the other fundamental forces of nature. The Earth is not affected by expansion.

3. Jul 23, 2015

### Shankar Dev

Yeah but If Space will expansion on both side inner side or outer side then ?

4. Jul 23, 2015

### Staff: Mentor

I'm sorry but I cannot understand you.

5. Jul 23, 2015

### Chronos

the universe has no 'outer' side by definition.

6. Jul 23, 2015

### Shankar Dev

7. Jul 23, 2015

### Shankar Dev

I have not much knowledge about physics so can you help me sir ?

8. Jul 23, 2015

### newjerseyrunner

The space inside of all atoms expands, but it's to such a tiny degree that the forces of nature are far far more powerful and everything acts as it should. If space between an electron and proton expands a tiny tiny bit, it's less than the random motion of the electron anyway, that's why atoms don't fly apart due to expansion and it's the same for larger objects too. If the space inside the earth expands by a billionth of a micrometer, gravity will keep everything in place. The expansion of space is minuscule, it presents itself only over massive distances. Here is a thought experiment you can do. Imagine a meter stick in your hand. Now imagine a magic force that caused it to expand 5%. It's now 1.05 meters long, a significant amount, but look at each millimeter mark by itself. It's 1.05mm now, not really that big of a deal. Now extrapolate, if the universe expands by light years as a whole, the amount we'd notice it within the tiny little speck that's planet earth is next to nothing. Everything moves orders of magnitudes faster than the expansion of space except for at the most massive scales.

9. Jul 23, 2015

### Staff: Mentor

No, it doesn't. Atoms are bound systems. Bound systems do not expand.