This Is Why The Speed Of Gravity Must Equal The Speed Of Light

Ethan SiegelSenior Contributor
Starts With A Bang
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If the Sun were to spontaneously cease emitting light, we wouldn't know about it for about 8 minutes and 20 seconds. The light that's arriving here on Earth, right at this very moment, was emitted from the Sun's photosphere a finite amount of time in the past, and is only being seen now after a journey across the 150 million km (93 million miles) separating the Sun from the Earth. If the Sun were to go dark right now, we wouldn't find out until the light stopped arriving.

But what about gravitationally? If the Sun were spontaneously (somehow) removed from existence, how long would Earth remain in its elliptical orbit before flying off in a straight line? Believe it or not, the answer to this must be exactly the same amount of time as it was for light: 8 minutes and 20 seconds. The speed of gravity not only equals the speed of light to an incredibly precise degree observationally, but these two constants must be exactly equal theoretically, or General Relativity would fall apart. Here's the science behind why.
Link-->https://www.forbes.com/sites/starts..._medium=social&utm_term=Malorie/#5f350e272fc0

 

if a car was travelling at the speed of light, would the headlights work ?

 

I think they would, yes.
I've read a few articles about this, still don't understand at the "gut" level.

 

OK, Dr. Physicist, riddle me this!

If gravity does indeed travel at the speed of light, then what happens when galaxies are moving away from each other at faster than the speed of light?

Dark energy causes the space between galaxies to expand at a rate of (around) 70 km/s per megaparsec, called the Hubble Constant. (A parsec, a measure of distance, is around 3.25 light years. A megaparsec is, therefore, around 3,250 light years). The speed of light (and gravity) is 300,000 km/s. Dividing the speed of light by the Hubble Constant yields 4,286 megaparsecs. So two galaxies that are around 4,300 megaparsecs apart will be moving away from each other at faster than the speed of light.

Do the two galaxies 'feel' each other's mass as gravity? In the same way that the two galaxies won't see each other any more because the light from one won't 'catch up' to the other, will they not 'feel' each other any more because the gravity waves from one won't 'catch up' to the other?

And if not, then what does that imply for the universe?

 

I like how some members talk to them selves and answer themselves.

I was once told that if a person talks to themselves, they are higher intelligent...but if that mother fucker answers himself, stay the fuck away as the mother fucker aint fastened too tight.

 

Glad Y'all made the class !

My 2-cents comes closest to dark matter being the propulsion spring that works in the absence stellular gravity. Also being the Johnny Appleseed of cosmic stuff left in the wake of the centrifugal jailbreaks!

 

My ladder reaches 20' into the sky, much after that, me dont much care.

What I have noticed lately, is some folks will climb to the top of the tallest tree they can find in order to tell a lie, rather than stand on firm ground and tell the truth.

What do you make of that?

 

Tales and Tall tales are part of the stuff left in the jailbreaks.

Of interest to me is the stuff that's such an incredible and suspiciously disingenuous that you're fricked if you don't and learn that ya had to be fricked for going into that rabbit hole of ambiguity

 

I see that rabbit hole, I tend to jump over it.

 

Me->FOOLS RUSH IN

 

The speed of gravity. I never thought about it before. Thank you for giving me something to think about this morning.