WHAT IS GRAVITY This has been a favorite question of mine since I learned the apple didn't really hit Sir Isaac in the head. If you are not getting the answers to your questions, maybe you are asking the wrong questions. This is the quest of many, to first define the questions well and then find the answer to those questions. What do you think the question should be to help define gravity A great topic for discussion on the Physics Forums Site.
Einstein defined the effects of gravity but did not believe gravity was a force. Gravity is a natural consequence of the presence of matter causing a curvature of spacetime. This does not define gravity.
Why is gravity weaker than the other forces, does it push or pull or both, is gravity a fundamental force The four fundamental forces of nature generally accepted today are listed below in order of strength in relation to each other. Among these forces, gravity is not only the weakest, but also the least understood.
- Strong Interaction
- Weak Interaction
|Fundamental force||Relative Strength|
Gravity & Dark Energy
Gravity vs. Dark Energy, fundamental force or not Gravity has acquired additional names attempting to better define it's presence; Dark Gravity, Supergravity, Quantum Gravity and maybe even Dark Fluid being the latest attempt to define our understanding of gravity. But the big question remains, is gravity a fundamental force of nature or not Or has that question already been answered by one of these additions without us realizing it, like the - i.e. Inflationary Theory with Cosmological Constant
Space / Time & Einstein
Time in motion. As E = mc2 is that deep connection between mass & energy and is Einstein's most widely recognized equation, the difference in time elapsed from a stationary object & an object in relative motion is a factor of gamma , another very important Einstein formula, for calculating Time Dilation. The rate at which time passes is affected by motion. Different rates are determined by speed.
Is time travel possible It is easy to time travel at night, just look up at the moon. You are seeing what happened there about 1.3 seconds ago, you are looking into the past. Want to go back in time even further Look at Venus, Mars, Jupiter, Saturn. Even further you say Look off into our galaxy to other solar systems (light from the nearest solar system stars, the Alpha Centauri system, takes more than 4 light years to reach us) We can now peer off into distance systems of other galaxies, to the beginning 13.73 ± 0.12 billion years ago. You are seeing time that has past, due to the speed limit of light (aprox. 186,000 Mps). See chart below for light times in our solar system...
Sun Time light takes to reach planets Mercury 193.0 seconds or 3.2 minutes Venus 360.0 seconds or 6.0 minutes Earth 499.0 seconds or 8.3 minutes Mars 759.9 seconds or 12.6 minutes Jupiter 2595.0 seconds or 43.2 minutes Saturn 4759.0 seconds or 79.3 minutes Uranus 9575.0 seconds or 159.6 minutes Neptune 14998.0 seconds or 4.1 hours Pluto* 19680.0 seconds or 5.5 hours
The big question to be answered from Relativity, is still, what is gravity and can we make all this work with the very small (the quantum)