If gravity acts at the speed of light and not instantaneously why don't planets simply drift away from each other since they are never being pulled "directly" toward one another?
Any replies would be greatly appreciated.
If gravity acts at the speed of light and not instantaneously why don't planets simply drift away from each other since...
Benjamin Ross
Zachary Hall
Why?
Connor Hall
>If light only propagates at the speed of light then why aren't all the planets dark because they are never being shined on "directly"?
Luke Flores
Planets are pulled - continuously - toward their sun, and thus orbit that sun. Orbital perturbations arise from attraction between planets.
What question/issue are you asking about?
Henry Scott
If the sun is moving through space in a path that is not perfectly straight then all the bodies orbiting it will have a "lag" since they are being pulled toward a location behind and to the side of the sun at all times. The faster the sun in question is travelling the longer the lag. Does this lag have any measurable effect? It seems so counter intuitive that an orbit can be stable since the planet has to adjust to its suns own trajectory while also "keeping up" with it
Cooper Perry
The forces are "instantaneous", it's the principles of a vector field.
Basically every single point of the universe "feels" the action of our sun, albeit of course with a diminishing effect. (precisely, the effect is proportional to the inverse of the square of the distance.)
Don't think of gravity as vectors travelling through space at the speed of light, think of it as a vector field.
Blake Barnes
Thanks user!
Robert Bennett
>it will have a "lag" since they are being pulled toward a location behind and to the side of the sun at all times
The speed of light is so much faster than the relative speeds of orbiting objects, there wouldn't be much lag, certainly not enough to disrupt the orbit.
How far could the sun move in 8 minutes relative to the earth? in 5 hours for Pluto?
Anthony Flores
Who said gravity is limited to the speed of light?
Gravity bends light. Gravity can be forced to turn at a 45 degree angle, but nothing physical (photons) can do this without stopping.
Only my own theory dealing with structural engineering. There are certainly some geeky science guys here I defer to in specifics though not in common sense.
Landon Sullivan
Einstein did.
>what is general relativity?
James Davis
Planets don't "drift" or get "pulled", they are continuously falling.
Nicholas Parker
Your view of orbits is incorrect. You're assuming something like a yo-yo on a string.
Eli Hernandez
>The forces are "instantaneous"
This is incorrect.
Jordan Young
Completely incorrect. I guess this user's never heard of gravity waves (which would be impossible to deserve as spacetime perturbations if they went from A to B instantaneously). As others have mentioned, there is a lag but the pull is continuous. A star one light year away takes roughly a year to tug on me, but at every moment I'll feel the previous tugs. You'd never notice this, though, as gravity and EM fall of sharply as distance (so can often be approximated as instantaneous even though that's super incorrect theoretically)
Aiden Foster
Only true for a 2 body system. Bet you're killing HS right now.
Luis Davis
>every single point of the universe "feels" the action of our sun
this souns like some new age bullshit
>le we are all connected and shit
>electric field from my pubes are felt in the whole universe
Easton Turner
well, depending on the size of the universe, and the age of the sun, that might be true
everything in the observable universe feels the gravity at least
Cameron Phillips
does that feel even do anything
Logan Perry
Because the waves are continuous
Sun doesn't send one gravitational wave and wait for it to reach to send another one (at least that's what I assumed you thought), it continuously sends waves
Or if what you're asking is that why gravitational waves aren't pulling planets to the previous locations, it's because it doesn't take that long for it to reach
image.gsfc.nasa.gov
Jaxson Edwards
that feel does many things user
Jaxon Jenkins
Which is why I put quotations mark on it. It's a simplification, right, but at our scale it doesn't matter much.
Luis Barnes
If a firehose doesn't shoot water to its destination instantly, why can you ever hit moving targets?
Adam Anderson
Because cognition of the relative locations in timespace is necessary first?
Wyatt Ramirez
Jesus Christ /sci, I am disappointed
all the responses in this thread so far are wrong or irrelevant
The correct answer is that planets are attracted not towards the position of where the Sun was, but (almost) towards the position where the Sun is at the present, even tough the speed of light is finite
this only works if accelerations are very low, which is a very good approximation for our a solar system, but fails for example for quickly orbiting black holes, which do inspiral over time precisely because the speed of light is not instantaneous
Adrian Thomas
Structural engineer here.
You're fucking dumb.
Thanks.
Michael Baker
White circle is lightbeam
Black circle is mass before it recieved light
>light rotates and bends around mass trough reflection?
Owen Hall
Brown = projection?
Red = energy