July 12th, 2008, 01:02 AM
My question is, If sun is to blast,explode,or disappear at once some how, will the effect of that have an instant effect on the earth. Or earth will continue in the orbit for 8mins and then have the effect.?
I know it might not be possible. But the Question is gravity have instant effect or with the speed of light.??
It's an interesting question. I'm assuming you mean to ask what would happen if the sun just winked out of existence. It's purely academic, however. The matter and energy that make up the sun can move, but never disappear. In fact, it can only move at the speed of light or slower......
We can make a lot of very interesting questions out of this, however. What if the sun began moving away from us at the speed of light? I wonder what our orbit would look like then.
The effect of gravity propagates at the speed of light.
Newton believed that it would have an instant effect. However when Einstein made his Theory of Relativity it argued against Newtons original hypothesis and it is now thought that if the Sun exploded we would not know it for 8 minutes.
.... except that the explosion would only happen at the speed of light. But yeah, we'd experience all effects, even the change in gravity, 8 minutes late.
The Earth would continue to orbit the sun for the time it takes light to travel to Earth.
When Einstein made Special relativity, he realised eventually that his theory disagreed with Newton's idea of gravity. So thus he had to formulate a new theory on gravity to explain how gravity could still work. Hence, General relativity. It is ironic that sometimes you create one thing. You create multiple theologies when you never intened to. Coincidences,.
So to answer your questions. What we observe, the effect would occur at the speed of light, and thus take 8 minutes to take affect.
Would someone mind explaining the steps that were taken by the original theorist to reach an understanding that the effect of gravity has something to do with the speed of light?
Are there any reproducible experiments that would show this to be true? Or is this all theoretical conjecture based on good faith assumptions?
Just asking for some citations, or links to help verify this assertion.
OK Here:
Newton (before Einstein) stated that if the sun disappeared instantly, then all the planets orbiting the sun would all, at the same time spin off into the universe.
Now that means that that effect from the sun to each individual planet would take more or less time if we stand on Earth and observe the effect ourselves.
For instance, it takes light to travel to Earth, roughly 8 minutes. For Jupiter it takes apparently: 43 minutes (http://au.answers.yahoo.com/question...6140022AAgJwx8) But this may not be truly valid.
Anyway, so you can see that if by Newtons explanation, Jupiter and Earth would go off at the same time. But Einstein in Special relativity said NOTHING can travel faster than light. That includes the speed of gravity. So when one day Einstein thought about this Sun vanishing phenomena, he realised that he had shown Newtons statement to be wrong, and thus had to explain the effect of the sun vanishing and the effect not happening faster than the speed of light. It took him over a decade, but to explain this effect he created General relativity.
Here is a video that makes much more sense:
http://uk.youtube.com/watch?v=tpbGuu...0721F4&index=0
Sorry about the quality.
Energy (light) is a product. Once created and sent from the source, it travels at the suggested speed effecting matter to an ever decreasing degree (from dispersement), regardless what happens to its source. There is no reason to believe one photon from 10-13 bly away is any less powerful than one photon from out sun.
Gravity is an effect on matter and should exist only while the sources exist, in this case much like a string attached to two or multiple objects. If one of the sources instantly disappears, the string may still exist, but the effect should instantly cease.
If 99.95% of matter in one system disappears (our sun), there would be instantly another source for 98% of the total effect between the remaining matter, Jupiter. While the effects would be instant, matter still has limitations for acceleration and velocity. The probability is most remaining solar system matter would end up destroying Jupiter, as very large asteroids would earth, leaving a near dust cloud to drift through space.
This is my opinion only, I have no source. I do think there are some unknown things about gravity, which many people would agree....
Not half.Originally Posted by jackson33
Einstein's gravity predictions were much more complicated than Newtons, talking about "space time curvature" instead of a raw force. 2 major things confirmed it:
1) - The eliptical orbit of Mercury around the sun has something called a "precession" which means that the egg-shaped elipse pattern of it's orbit shifts a few degrees every few years. (Which has always been seen as a paradox in Newtonian mechanics)
The mathematics of Einstein's relativity theory not only predicted it, but actually demanded it, and nailed it's exact magnitude. (Einstein reportedly had heart palpitations when he finished working the formula out and realized it was such a perfect match)
2) - The Eddington expedition during a solar eclipse that set out to measure the shift in position of stars behind the sun (due to the sun's gravity pulling on the light as it passes).
The truth is that both Newton, and Einstein predicted that the light would be curved as it passed the sun, but Einstein predicted a different amount than Newton. Einstein turned out to be the one that was right.
The experiment has been repeated with greater accuracy since we got into space using satellites which can set blinders that block the sun perfectly from their view, leaving a clearer picture of what's behind it, and they always get Einstein's numbers, rather than Newton's.
It should be pointed out that like the light bending around the Sun, it wasn't the precession per se, that was the problem, but the fact that the amount of precession was more than could be accounted for by Newton's laws.
One of the possible explanations floated for the excess precession was the existence of a planet inside the orbit of Mercury. This proposed planet was named Vulcan. Though there were a few false alarms, no such planet was ever found and with Einstein's Relativity it was no longer necessary.
The thing about Albert's space-time distortion as an explanation of gravitational effect seems to be a little off kilter to me though? I mean, warping space should effect the absolute position of an object, but not it's local vector of movement, nor it's local position.
That is to say.. if you alter the coordinate system of an environment, locally you experience nothing out of the usual.. Everything that can be experienced should be effected by that coordinate grid. a particle moving from p(x1,y1,z1) to p(x2,y2,z2) would speed or slow from an external point of reference (due to the space warping causing the distance between these two points to change), but a local observer on the same coordinate grid would not be able to recognize that change without an external POR. That same particle should also experience absolute volume changes as it enters or exits regions of higher or lower density space; but not local changes.
A moving object with a trajectory that bypasses a massive object should dip in towards that object, and finally ascend back away from the object to continue on it's original trajectory with no alteration what so ever... IF a space warp were the only thing that caused the initial 'attraction', but this would only be visible from an external point of reference, as that space density gradient would cause observations from a local POR to appear as though the object just flew right past it without experiencing any sort of vector changes.
A simple space warp does not seem to account for locally observed acceleration, unless I'm totally lost with what is actually meant by 'warped' space...
Whatever way you look at it though, the effect of gravity isn't necessarily caused by a physical moving particle, therefore it doesn't necessarily have to adhere to the speed of light, since we don't really know weather or not something is actually moving at all? I know we have been in search of the fabled gravitron.. but we have not been able to isolate or identify a real case of it yet. Looks to me like the answer to all of this is still up for grabs.
I think sometimes it's just the language that's confusing. Trying to visualize space-time-distortion is always going to be a little bit of a dead end because it's not really a visual thing. Even the analogy of pushing down part of a trampoline to show how objects move to the part that's distorted probably doesn't capture the real meaning of the idea.
July 14th, 2008, 07:32 AM
There was a recent experiment/observation that has established that gravity propagates at the speed of light.
So it is not instantaneous.
Cosmo
If the gravity of a black hole can't exceed the speed of light, why is the event horizon much wider than the source of gravity i.e. how can gravity catch up?
I'm not sure, but I know the gravity moves spacetime. Hope that helps.
thanks guys.
Exactly!!
thats what i also think. How the gravity of a blackhole catchup the light.
I think that the effect will be instantanious.
So i think there is some other way of explaining the universe, which can explain the effect of gravity.
Any idea of u guys or any new theory of u guys???
Maybe it can be ...made to conform <_< ... if we say prior gravity effect kinda lingers or orbits the black hole... then light runs into it.
I'm highly skeptical of the whole photon-god trip BTW - I'm just playing around now.
Changes in gravity propagate at the speed of light. If the black hole were to magically instantaneously get a lot more mass so that its event horizon increased, there would be a very slight delay between when the extra mass appeared and when the outer edge of the even horizon moved outward.
It’s not like gravity is chasing after any light that might come out of the black hole so that it can catch it and pull it back. The light is pulled back by gravity that is already present in the space that the light is trying to pass through.
As was already pointed out by otheres here, there are several experiments which have shown that gravity propagates at the speed of light. You might find the fact that gravity propagates at the speed of light annoying or confusing, but that doesn’t change the fact that we have experimental verification.
July 16th, 2008, 12:39 PM
if you guys want to check out an interesting theory on how gravity, magnatism, and weak/strong work---- go here www.PanTheory.org
If energy is subject to gravity, how could energy escape gravity in the first place, as in our sun? If gravity is proportionate to the mass and BH are mass, at what point does the mass/gravity relation become this powerful. We do receive light energy from some very large concentrations of mass, trillion plus times our solar mass and BH have a mass no more that the original star or the consumed mass.
If energy is subject to bending and proportionate to mass concentrations, ie bend more as the mass increases, no observation of light waves or energy detection could be accurate to location. In turn BH's should be dotted with apparent stars. IMO...
The sun's gravity is not strong enough to stop light, so light gets out. The sun has less gravity than a black hole.
It's not the mass that matters, it's the gravity. Gravity depends on mass, but it also depends on your distance from the center of mass. In a black hole the mass is all smashed into a very small space, so you are closer to the center of gravity. Mars has less than 1/10th the mass of the earth, but it still has 1/3 the gravity because it is smaller, so you are closer to the center center of mass. A black hole isn't any more massive than the star that created the black hole. But since the matter in the black hole is in a much much smaller area than the star, the force of gravity at the surface is stronger.If gravity is proportionate to the mass and BH are mass, at what point does the mass/gravity relation become this powerful.
See above; it's not just the amount of mass that matters, it's how close you are to the center of mass.We do receive light energy from some very large concentrations of mass, trillion plus times our solar mass and BH have a mass no more that the original star or the consumed mass.
I assume that by "energy" you mean "light". In any case, astronomers do have to take the way gravity bends light into account when they make observations.If energy is subject to bending and proportionate to mass concentrations, ie bend more as the mass increases, no observation of light waves or energy detection could be accurate to location. In turn BH's should be dotted with apparent stars. IMO...
I personnaly do not believe black holes exist because IMO, they would/should be seen as having a 'halo' of light surrounding the 'event horizon', that would 'bend' the light around it to create dim halos.
With our powerful telescopes and technology, I would say one should be nearby and detected because when the Milky Way galaxy was first created, there were many more 'blue giant' stars that have been spent and their remains left to be detected. Since none are seen, they cannot be real.
Cosmo
That's nearer what I feel is happening. The gravity is not radiating from the "source".
That is a very excellent point. Just like how changes in a DC electrical circuit's resistance are only experienced at the speed of light. Or similar to that I guess.Changes in gravity propagate at the speed of light. If the black hole were to magically instantaneously get a lot more mass so that its event horizon increased, there would be a very slight delay between when the extra mass appeared and when the outer edge of the even horizon moved outward.
This prompts a question: we know gravity depends on the mass of *both* objects, so wouldn't the force have to wait to begin pulling until both objects are present? (IE. both the light wave, and the black hole)
It’s not like gravity is chasing after any light that might come out of the black hole so that it can catch it and pull it back. The light is pulled back by gravity that is already present in the space that the light is trying to pass through.
It's just confusing to try and think of what it means when we apply it to real life. I wonder about stars on the outer rim of a galaxy, quite a few light years out from the center.
As was already pointed out by otheres here, there are several experiments which have shown that gravity propagates at the speed of light. You might find the fact that gravity propagates at the speed of light annoying or confusing, but that doesn’t change the fact that we have experimental verification.
I wonder what effect, if any, the information delay has on their orbits.
Sorry for the late response Kojax, been working a lot this week.I think sometimes it's just the language that's confusing. Trying to visualize space-time-distortion is always going to be a little bit of a dead end because it's not really a visual thing. Even the analogy of pushing down part of a trampoline to show how objects move to the part that's distorted probably doesn't capture the real meaning of the idea.
But yes, I agree that the whole trampoline illustration doesn't do the concept justice either, because it relies on an external force/effect to act on the objects used to illustrate the idea to start with.. take out that effect and you get no space warping and no illustration.
I think I have a decent understanding of how to visualize space densities and transformations.. been at it for many years with 3d programming; I have a good grasp of how to mentally visualize 4 5 and 6 dimensional space, and it's interactions. To illustrate them on paper without math would be a mighty task indeed though!
At any rate.. my qualms come probably more from my inability to distinguish the difference between space and matter.
Right. Let's see, the most massive stars are about 100 times the mass of the Sun, so let's assume a black hole with this mass. (This is being very generous, as in its death throes a star throws off the majority of its mass, leaving only a fraction behind to form a black hole.)I personnaly do not believe black holes exist because IMO, they would/should be seen as having a 'halo' of light surrounding the 'event horizon', that would 'bend' the light around it to create dim halos.
With our powerful telescopes and technology, I would say one should be nearby and detected because when the Milky Way galaxy was first created, there were many more 'blue giant' stars that have been spent and their remains left to be detected. Since none are seen, they cannot be real.
Cosmo
A black hole of 100 solar masses would have an event horizon with a radius of just under 300 km. At the Hubble telescope's resolution of 0.05 arc-second, the maximum distance at which the Hubble could resolve said dim ring of light (And by resolve, I mean just detect as an individual object, not resolve as a ring) would be 2.4e9 km.
So unless said 100 solar mass black hole was located somewhere between the orbits of Saturn and Uranus, I wouldn't hold on to any hopes of seeing it.
acording to einstein gravity is not instentanious
Gravity doesn't "pull" at light, since photons have no mass. The photons merely follow the curvature/gravity of space-time.This prompts a question: we know gravity depends on the mass of *both* objects, so wouldn't the force have to wait to begin pulling until both objects are present? (IE. both the light wave, and the black hole)
The event horizon is the boundary where the escape velocity equals the speed of light. As Scifor says, it is the distance from the centre of gravity that makes a difference. Theoretically you could shrink the earth until the Schwarzschild radius is above the surface, after which no light would be able to escape from the surface. Escape velocity depends on the mass of the object and the distance from the centre of gravity of the mass. Mass bends surrounding space (gravity) and the Schwarzschild radius denotes the point where space is curved inwards, totally isolating the inside from the outside (maybe except for Hawking radiation).If energy is subject to gravity, how could energy escape gravity in the first place, as in our sun?
Cute, but your estimate of BH sizes and distances are over and under estimated.Right. Let's see, the most massive stars are about 100 times the mass of the Sun, so let's assume a black hole with this mass. (This is being very generous, as in its death throes a star throws off the majority of its mass, leaving only a fraction behind to form a black hole.)I personnaly do not believe black holes exist because IMO, they would/should be seen as having a 'halo' of light surrounding the 'event horizon', that would 'bend' the light around it to create dim halos.
With our powerful telescopes and technology, I would say one should be nearby and detected because when the Milky Way galaxy was first created, there were many more 'blue giant' stars that have been spent and their remains left to be detected. Since none are seen, they cannot be real.
Cosmo
A black hole of 100 solar masses would have an event horizon with a radius of just under 300 km. At the Hubble telescope's resolution of 0.05 arc-second, the maximum distance at which the Hubble could resolve said dim ring of light (And by resolve, I mean just detect as an individual object, not resolve as a ring) would be 2.4e9 km.
So unless said 100 solar mass black hole was located somewhere between the orbits of Saturn and Uranus, I wouldn't hold on to any hopes of seeing it.
And placing them in between Saturn and Uranus would create another miniiture galaxy since they are now accepted to exist in the central regions of galaxies.
They are also supposed to be detected by gravitational effects outside of galaxies.
But my argument centers on 'numbers'.
I think the 'blue giant' stars of the past outnumber the estimated numbers that exist today by a much larger margin.
Cosmo
Well, a bh with 100 solar masses would certainly attract the planets more strongly than the sun does. (100 times more strongly, to be exact. :wink: )
I'm also not sure if 100 solar masses is enough matter to cause a bh to come into existence. It takes the combined gravitational effect of a whole lot of matter all being in one place to get matter to become that compact.
What I think we're forgetting is that a bh does more than just stop light that would otherwise be able to pass near it. It warps light out to a further distance, so if a bh like that one were even within a few light years of us, I'm thinking we'd probably notice some of the stars in its background getting bent out of shape. ( I could be wrong, though. It took a while to find Pluto, so we're often blind even to our own solar system.)
There is confusion here between "stellar" black holes, Those formed by the death of large stars and the Super-massive black holes that reside at the center of galaxies.
The latter are formed during the formation of the galaxy by collection of matter at the center of the galaxy and can mass millions of stellar masses.
The first are formed from individual stars and can mass as small as 2.7 solar masses. (the average mass for a stellar black hole is 10 solar masses.)
Since cosmo was talking about the remains of blue giants, the black holes let behind would be of the Stellar variety, and 100 solar masses would be on the upper limit for size.
The point being that even a very large stellar black hole would not be directly detectable at any reasonable distance by the method proposed. IOW, Cosmo's argument against the existance of BH's is flawed.
This is really a topic of 'conjecture', so it is just a matter of opinion.
I still say that BH's in isolation should be surrounded by bent light to form halo's.
With our very large telescopes and advanced technology, one should be seen.
When that day comes, than I will believe in their existence. Ha ha.
Nuff said.
Cosmo
FACT: Stellar Black Holes will not be more massive than the the star from which they were formed.This is really a topic of 'conjecture', so it is just a matter of opinion.
I still say that BH's in isolation should be surrounded by bent light to form halo's.
With our very large telescopes and advanced technology, one should be seen.
When that day comes, than I will believe in their existence. Ha ha.
Nuff said.
Cosmo
FACT: There is a limit to the size of stars.
therefore:
FACT: The radii of even the largest stellar black holes would be less than 1000 km
FACT: the resolution of our telescopes are not great enough to resolve an object that small unless it is very close.
All your hand-waving aside, what you personally believe makes no difference.
Of course, no telescope can see the bh itself, only the bent light. And the trick with bent light is distinguishing what we're seeing from what we'd see if there were no bh there to bend it.
In some rare cases we can tell pretty easily, like if we see 4 identical galaxies focused around a single point in space, but otherwise you have to look for its gravitational effect on other celestial objects to find one.
My argument is based on the past where 'new' galaxy formations would be 'loaded' with blue giant stars.FACT: Stellar Black Holes will not be more massive than the the star from which they were formed.This is really a topic of 'conjecture', so it is just a matter of opinion.
I still say that BH's in isolation should be surrounded by bent light to form halo's.
With our very large telescopes and advanced technology, one should be seen.
When that day comes, than I will believe in their existence. Ha ha.
Nuff said.
Cosmo
FACT: There is a limit to the size of stars.
therefore:
FACT: The radii of even the largest stellar black holes would be less than 1000 km
FACT: the resolution of our telescopes are not great enough to resolve an object that small unless it is very close.
All your hand-waving aside, what you personally believe makes no difference.
So the number of evolved red dwarf stars today may have been blue stars in the past that were not big enough to form BH's.
But there was a much greater number of giant BS's in the past and there would have been at least one or two in our vicinity outside our solar system.
So there is no need to argue this point any further.
Thank you Janus for your views anyway.
Cosmo
Of course there's no need, but my purposes here are entertainment. Are you suggesting that there would probably have been some blue stars around this area a long time ago, and some of them might have become bh's?
Of course, the other way we detect BH's, other than light, is to see if any objects nearby are being affected by their gravity. If there were a black hole sized star anywhere near our solar system, I imagine it would mess with the orbits of the planets a little.
From close up, we would see the black area of the BH distorted by how it's gravity bends light. I don't think there would be a halo (other than dust and gas inspired) as light is either going inside or going to escape.
For your information, objects with that radii are now being detected outside the Pluto region and beyond.FACT: Stellar Black Holes will not be more massive than the the star from which they were formed.This is really a topic of 'conjecture', so it is just a matter of opinion.
I still say that BH's in isolation should be surrounded by bent light to form halo's.
With our very large telescopes and advanced technology, one should be seen.
When that day comes, than I will believe in their existence. Ha ha.
Nuff said.
Cosmo
FACT: There is a limit to the size of stars.
therefore:
FACT: The radii of even the largest stellar black holes would be less than 1000 km
FACT: the resolution of our telescopes are not great enough to resolve an object that small unless it is very close.
All your hand-waving aside, what you personally believe makes no difference.
These objects have diameters similar to Pluto and their reflections of Sun light must be very low in magnitude since they are just now being discovered.
Cosmo
any answer one way or another is theory as we cannot duplicate winking out of exsistance matter. we could only move it away at a slower then speed of light which would invalidate the test.
personally I think the effects would be instantanious.
it mostly comes down to what is gravity (force, tiny strings, extra dimensions?) and that we dont know yet.
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