-
-
-------------------------- 2438 - GRAVITY - traveling at the speed of light?
-
- Why Does Gravity Travel at the Speed of Light?
-
- Two neutron stars collide; the resulting gravitational wave spread at the speed of light. (Request a separate Review if you want to learn what neutron stars are?) The dead cores of these two stars collided 130 million years ago in a galaxy somewhat far away.
-
- The collision was so extreme that it caused a wrinkle in space-time, called a gravitational wave. That gravitational wave and the light from the stellar explosion traveled together across the cosmos. They arrived at Earth simultaneously at 6:41 a.m. Eastern on August 17, 2019.
-
- This detection proved to astronomers that their theory that gravity traveled at the speed of light was correct. We all know light obeys a speed limit of 186,000 miles per second. Nothing travels faster. But why should gravity travel at the same speed?
-
- Albert Einstein’s general relativity, or theory of gravity, predicted gravitational waves, like light waves, existed a century ago. At the same time Einstein overthrew Isaac Newton’s idea of “absolute time.”
-
- Newton thought time marched onward everywhere at an identical pace regardless of how we perceived it. Regardless of our own motion through space. By that line of thinking, one second on Earth is one second near a black hole (which Newton didn’t know existed). That is regardless of the influence of gravity or the curvature of space.
-
- Newton thought gravity acted instantaneously. Distance didn’t matter. But, then Einstein showed that time is relative. It changes with speed and in the presence of gravity.
-
- One of the ramifications of his theory is that you can’t have simultaneous actions at a distance. So information of any kind has a finite speed, whether it’s a photon, the light-carrying particle, or a graviton, which carries the force of gravity. Which also has not yet been discovered, except in theory.
-
- In relativity, there is a ‘speed of information’ , the maximum speed that you can send information from one point to another,” In electromagnetism, when you shake an electron, it creates a change in the electric field that spreads out at the speed of light. Gravity works the same way. Shake a mass and the change in the gravitational field, the gravitational wave, propagates at that same speed.
-
- So the fact that the speed of gravitational waves is equal to the speed of electromagnetic waves is simply because they both travel at the speed of information.
-
- There’s an easy way to picture this. If the Sun went dark instantaneously we would not know it until 8 minutes later., when the last bit of light reached us.
-
- The same delay would occur with gravity. If the Sun disappeared altogether the
Earth would continue to orbit for another 8 minutes before it would shoot off into space in a straight line.
-
- The same would occur at different times for the other planets, the comets and the asteroids.
-
- What is gravity really? If there is no mass there is no gravity. We understand electromagnetism pretty well. Otherwise I would not be typing this. But, what is holding me in my chair is still much more mysterious. May you live in interesting times.
-
- See Review 2014 that lists 12 more Reviews about Gravity, and the property of space - time.
-
- August 27, 2019
----------------------------------------------------------------------------------------
----- Comments appreciated and Pass it on to whomever is interested. ----
--- Some reviews are at: -------------- http://jdetrick.blogspot.com -----
-- email feedback, corrections, request for copies or Index of all reviews
--- to: ------ jamesdetrick@comcast.net ------ “Jim Detrick” -----------
- https://plus.google.com/u/0/ -- www.facebook.com -- www.twitter.com
--------------------- Tuesday, August 27, 2019 --------------------
-----------------------------------------------------------------------------------------
No comments:
Post a Comment