shockwaves in space

[jajrussel]

I was watching a video where it was said that if the Sun were to suddenly cease to exist it would be a little over 8 minutes before we would see the light go out and feel the shock waves etc.

Does this mean that a shock wave in space would travel at c, did I misunderstand the statement, or maybe is it that what I assume a shock wave to be, is not the same as would be deemed a shock wave on earth?

If I see two enteracting galaxies millions of light years away should I expect to have to waite for the shockwave, much like lightning then thunder here on earth, or should I expect to detect the wave now?

Or do we detect the wave then look for the cause?

[swansont]

The spacetime curvature cause by the sun would have to cease, and that would propagate at c.

[Country Boy]

No "shock wave" would be involved.  It just means that since the light from the sun takes a little more than 8 minutes to travel the approximately 93 million miles from the sun to the earth, we would see the sun "go out" only a little more than 8 minutes later.  I don't know what "shockwave" you are talking about.

[koti]

If something blows up in space, the detonation shockwave would travel more or less the same velocity as on earth (minus air resistance, gravity, temperature differences) The detonation shockwave velocity differs betwen different compounds - gunpowder, nuclear detonation, a baloon blowing up would all have different shockwave velocities. If the sun disapeared in an instant without detonation, the only „shockwave” we would experience would be lack of gravity normally caused by the sun and like swansont said, it would take ~8min for us to notice. I presume the implication would be that the earth would skew out of its orbit around the non existant sun after those 8 minutes would have passed. Oh, and would get cold. Really cold and really fast.

Edited November 15, 2017 by koti

[jajrussel]

53 minutes ago, swansont said:

The spacetime curvature cause by the sun would have to cease, and that would propagate at c.

 

16 minutes ago, koti said:

If something blows up in space, the detonation shockwave would travel more or less the same velocity as on earth (minus air resistance, gravity, temperature differences) The detonation shockwave velocity differs betwen different compounds - gunpowder, nuclear detonation, a baloon blowing up would all have different shockwave velocities. If the sun disapeared in an instant without detonation, the only „shockwave” we would experience would be lack of gravity normally caused by the sun and like swansont said, it would take ~8min for us to notice. I presume the implication would be that the earth would skew out of its orbit around the non existant sun after those 8 minutes would have passed. Oh, and would get cold. Really cold and really fast.

Nothing in space, such as material objects, magnetic fields, gravatational feilds, etc. would effect the propagation rate?

so, it really wouldn't matter if I were talking about the Sun or two enteracting galxies millions of lightyears away?

When they write about measuring the propagation rate of Supernova shockwave what are they talking about? I kind of liked your use of the word propagation, so I may have misused it in regard to the Supernova shockwave.

[swansont]

5 minutes ago, jajrussel said:

 

Nothing in space, such as material objects, magnetic fields, gravatational feilds, etc. would effect the propagation rate?

so, it really wouldn't matter if I were talking about the Sun or two enteracting galxies millions of lightyears away?

When they write about measuring the propagation rate of Supernova shockwave what are they talking about? I kind of liked your use of the word propagation, so I may have misused it in regard to the Supernova shockwave.

The shockwave from a supernova might be referring to the ejected matter, which would travel much slower than c. But you weren't talking about supernovae.

[koti]

44 minutes ago, jajrussel said:

 

Nothing in space, such as material objects, magnetic fields, gravatational feilds, etc. would effect the propagation rate?

 

Propagation rate of what? The light emitted or the shockwave emitted by the sun or supernova ?

 

Quote

so, it really wouldn't matter if I were talking about the Sun or two enteracting galxies millions of lightyears away?

 

You have to be more specific...what won't matter ?
 

Quote

When they write about measuring the propagation rate of Supernova shockwave what are they talking about? I kind of liked your use of the word propagation, so I may have misused it in regard to the Supernova shockwave.

Most likely they are referring to the vast amounts of light, energy and matter a supernova emits. But probably they refer to light as a supernova emits incredible amounts of visible light.

Edited November 15, 2017 by koti

[jajrussel]

2 hours ago, swansont said:

The shockwave from a supernova might be referring to the ejected matter, which would travel much slower than c. But you weren't talking about supernovae.

 

1 hour ago, koti said:

Propagation rate of what? The light emitted or the shockwave emitted by the sun or supernova ?

 

You have to be more specific...what won't matter ?
 

Most likely they are referring to the vast amounts of light, energy and matter a supernova emits. But probably they refer to light as a supernova emits incredible amounts of visible light.

It was space.com an article  i believe dated  August 27. I don't know how to link to it nor do I know how to check the spelling in this reply box. I usually spell so badly that I don't even know for sure if I have spelled something wrong.

Am assuming now that they were talking about debris, since they were talking 8 miles per second.

I would have expected light to move at c.

I would have expected gravity's effect to react at less than c. I am likely wrong, but my thought is this because, if a sudden void is created i would expect things to move toward the void, before moving away. I figured that this would take time. Was also thinking of the sun as being more than a gravitational field. Guess I'm wrong. Still thinking it through.

note - the article didn't say anything about the sun suddenly disapearing that came from a CBSN interview I watched.

Edited November 15, 2017 by jajrussel

[koti]

20 minutes ago, jajrussel said:

 

It was space.com an article  i believe dated  August 27. I don't know how to link to it nor do I know how to check the spelling in this reply box. I usually spell so badly that I don't even know for sure if I have spelled something wrong.

Am assuming now that they were talking about debris, since they were talking 8 miles per second.

I would have expected light to move at c.

I would have expected gravity's effect to react at less than c. I am likely wrong, but my thought is this because, if a sudden void is created i would expect things to move toward the void, before moving away. I figured that this would take time. Was also thinking of the sun as being more than a gravitational field. Guess I'm wrong. Still thinking it through.

note - the article didn't say anything about the sun suddenly disapearing that came from a CBSN interview I watched.

Consider this and you can go from there:
- Light always moves at c - everywhere.
- Gravity always "moves" at c (hence the 8 minutes for us to notice the sun is missing) In Newtonian physics gravity is a force, in Einstein's General Relativity, gravity is curvature of space.

I don't really understand what you're talking about when referring to "the void" and I don't get the Sun being less or more than a gravitational field.
Don't worry about your spelling, I think it's very good.
 

[jajrussel]

2 minutes ago, koti said:

Consider this and you can go from there:
- Light always moves at c - everywhere.
- Gravity always "moves" at c (hence the 8 minutes for us to notice the sun is missing) In Newtonian physics gravity is a force, in Einstein's General Relativity, gravity is curvature of space.

I don't really understand what you're talking about when referring to "the void" and I don't get the Sun being less or more than a gravitational field.
Don't worry about your spelling, I think it's very good.
 

Thank you, I will try to explain. The void is the result of the "if" statement where the Sun is allowed to suddenly dispear. It exist it takes up space when it is there there is no void. Once again I am relying on the memory of something I once read. It was about a black hole and why they don't really just suck everything in. If I remeber corectly there was a force exibited by the black hole that tended to keeps things mostly to a safe distance. I don't remember what it was called or exactly how it was supposed to work . I am guilty of assuming that the Sun though much smaller would do the same thing though to a smaller degree, so if this force did exist or act in a manner simular to the one said to be exibited by a black hole then the Suns sudden disapearence should result in the planets suddenly moving toward the Sun before adjusting to their new direction.

Thanks for the comment on my spelling. Luckily, I remembered I can open up more than one web page at a time on this device before I attempted to spell debris.

[koti]

21 minutes ago, jajrussel said:

Thank you, I will try to explain. The void is the result of the "if" statement where the Sun is allowed to suddenly dispear. It exist it takes up space when it is there there is no void. Once again I am relying on the memory of something I once read. It was about a black hole and why they don't really just suck everything in. If I remeber corectly there was a force exibited by the black hole that tended to keeps things mostly to a safe distance. I don't remember what it was called or exactly how it was supposed to work . I am guilty of assuming that the Sun though much smaller would do the same thing though to a smaller degree, so if this force did exist or act in a manner simular to the one said to be exibited by a black hole then the Suns sudden disapearence should result in the planets suddenly moving toward the Sun before adjusting to their new direction.

Thanks for the comment on my spelling. Luckily, I remembered I can open up more than one web page at a time on this device before I attempted to spell debris.

If the sun would suddenly disappear, it would not leave any void or anything special behind except just regular empty space. The ripple in the curvature of that empty space would take ~8min to travel to earth and when it would get here, the earth would skew out of its orbit. None of the planets or any other matter would move towards the region of space which was occupied previously by the Sun.

[koti]

Note that empty space is always full of activity on the really small quantum level. So it’s never really empty. 

[jajrussel]

1 hour ago, koti said:

If the sun would suddenly disappear, it would not leave any void or anything special behind except just regular empty space. The ripple in the curvature of that empty space would take ~8min to travel to earth and when it would get here, the earth would skew out of its orbit. None of the planets or any other matter would move towards the region of space which was occupied previously by the Sun.

Okay, I am acepting that the effect would occure at c. I just found another website that to my best understanding says the mechanism that keeps things from getting sucked in per say is centripetal force. In my mind this slight mechanical change was causing a time difference.  But I still wonder what effect earth would have on this wave? Would Earth slow it down? Would the sudden change be enough to damage earth? Regardless of the waves speed any changes that occur on and through Earth can not occur at c. So I still wonder Do the lights go out first , and then earth trembles , or do the lights just go out as the wave passes by? What if the moon is on the oppisit side of Earth when the wave hits. Earth doesn't slow it down any before it hits the moon? Lol, I cain't seem to stop with the questions, anyway thanks, again.

11 minutes ago, koti said:

Note that empty space is always full of activity on the really small quantum level. So it’s never really empty. 

I watched a video that showed two galaxies coliding there is a lot of occupied space between there and here. Considering the amount of stuff that occupies space between both points I was having trouble accepting that any gravatational waves would get here at the same time as it's photons. I guess I am trying to aply a density to the wave that doesn't exist.

[koti]

45 minutes ago, jajrussel said:

Okay, I am acepting that the effect would occure at c. I just found another website that to my best understanding says the mechanism that keeps things from getting sucked in per say is centripetal force. In my mind this slight mechanical change was causing a time difference.  But I still wonder what effect earth would have on this wave? Would Earth slow it down? Would the sudden change be enough to damage earth? Regardless of the waves speed any changes that occur on and through Earth can not occur at c. So I still wonder Do the lights go out first , and then earth trembles , or do the lights just go out as the wave passes by? What if the moon is on the oppisit side of Earth when the wave hits. Earth doesn't slow it down any before it hits the moon? Lol, I cain't seem to stop with the questions, anyway thanks, again.

Slow down... rushing forward without getting the basics right will lead you nowhere

Lets get the basics right...we’re talking about gravity not some other force or energy coming from an explosion right? Lets concentrate on that - gravity. Sudden lack of gravity does not create any shockwave, if the Sun is to vanish from existance in an instant, there wouldn’t be any shockwave to hit the earth, no lights would go off (youre confusing this with electromagnetic pulse which can kill electronic devices if powerful enough) Earth would not have to slow down anything, it would simply loose its orbit around the Sun which would be missing at that point. Earth would not be damaged directly by the lack of gravity from the missing Sun, it would be damaged from going astray through space, lack of light and cooling down to space temperature which is close to absolute zero - the Earth with everything on it would die pretty quickly drifting alone in cold, dark, empty space. As for centripetal force - in Newtonian mechanics it provides orbits through gravity so it does prevent planets to be sucked in by the Sun’s higher gravity. We know from General Relativity that gravity is actually „curvature of space” and is considered by new models as not even a force. 

Edit: I hope swansont will not b slap me for my crude explanation. Also, I’m not a physycist, there are a lot more knowlegeable people here than me.

 

Edited November 15, 2017 by koti

[jajrussel]

6 minutes ago, koti said:

Slow down... rushing forward without getting the basics right will lead you nowhere

Lets get the basics right...we’re talking about gravity not some other force or energy coming from an explosion right? Lets concentrate on that - gravity. Sudden lack of gravity does not create any shockwave, if the Sun is to vanish from existance in an instant, there wouldn’t be any shockwave to hit the earth, no lights would go off (youre confusing this with electromagnetic pulse which can kill electronic devices if powerful enough) Earth would not have to slow down anything, it would simply loose its orbit around the Sun which would be missing at that point. Earth would not be damaged directly by the lack of gravity from the missing Sun, it would be damaged from going astray through space, lack of light and cooling down to space temperature which is close to absolute zero - the Earth with everything on it would die pretty quickly drifting alone in cold, dark, empty space. As for centripetal force - in Newtonian mechanics it provides orbits through gravity so it does prevent planets to be sucked in by the Sun’s higher gravity. We know from General Relativity that gravity is actually „curvature of space” and is considered by new models as not even a force. 

 

Okay, yes I am talking about gravity. The statement about the lights suddenly going out simply refers to the Suns sudden disapearance, and had nothing to do with electricity, or EMP waves. Yes I did expect the Suns sudden disapearing to create a gravitational shock wave as the curvature of space suddenly flattens out. And yes I expected there to be enough force to damage Earth. Sort of what happens when an astroid gets to close to Jupiter which I assume happens due to uneven gravitational forces acting on the astroid. And I suppose in conjunction with the word relativity gravity is not a force, but then what is it that tears the astroid apart if not the curvature of space being more in one spot than it is in annother? Wouldn't this be what the ripple you spoke of is?   If I am wrong about this I am wrong. I'm okay with it. I just like to think a thing through. If the change occurs at c how can there not be a large gravitational energy effect? Gravity does have an effect on space ,so I would imagine that its effect on matter would be noticable. For 8 minutes we don't notice anything  then suddenly we do. Are you saying that we are not even going to feel a bump?

[koti]

23 minutes ago, jajrussel said:

Okay, yes I am talking about gravity. The statement about the lights suddenly going out simply refers to the Suns sudden disapearance, and had nothing to do with electricity, or EMP waves. Yes I did expect the Suns sudden disapearing to create a gravitational shock wave as the curvature of space suddenly flattens out. And yes I expected there to be enough force to damage Earth. Sort of what happens when an astroid gets to close to Jupiter which I assume happens due to uneven gravitational forces acting on the astroid. And I suppose in conjunction with the word relativity gravity is not a force, but then what is it that tears the astroid apart if not the curvature of space being more in one spot than it is in annother? Wouldn't this be what the ripple you spoke of is?   If I am wrong about this I am wrong. I'm okay with it. I just like to think a thing through. If the change occurs at c how can there not be a large gravitational energy effect? Gravity does have an effect on space ,so I would imagine that its effect on matter would be noticable. For 8 minutes we don't notice anything  then suddenly we do. Are you saying that we are not even going to feel a bump?

„Gravity does have an effect on space” is a false statement in my opinion. Gravity is a distortion of space. Space can bend and we perceive that bending as gravity. I’d say we wouldn’t even feel a bump. 

Gravity however has a significant effect on matter, the fact that you and I are walking on earth instead of flying around weightless is good evidence of that effect, earths gravity is doing it. Gravity is also incredibly weak when you compare it to other 3 forces, its implications become interestingly apparent in special situations like extremely dense matter stuck in extremely small space - black holes. But lets leave black holes out of this as the physics of them are beyond me and you. 

From what you write I think you might still be confused about what is causing what in regard to space-gravity-matter. Digest this:

„Gravity is nothing more than space time curvature”

(space and time are inseparable under Einsteins Theory of General Relativity)

 

 

Edited November 15, 2017 by koti

[jajrussel]

22 minutes ago, koti said:

„Gravity does have an effect on space” is a false statement in my opinion. Gravity is a distortion of space. Space can bend and we perceive that bending as gravity. I’d say we wouldn’t even feel a bump. 

Gravity however has a significant effect on matter, the fact that you and I are walking on earth instead of flying around weightless is good evidence of that effect, earths gravity is doing it. Gravity is also incredibly weak when you compare it to other 3 forces, its implications become interestingly apparent in special situations like extremely dense matter stuck in extremely small space - black holes. But lets leave black holes out of this as the physics of them are beyond me and you. 

From what you write I think you might still be confused about what is causing what in regard to space-gravity-matter. Digest this:

„Gravity is nothing more than space time curvature”

(space and time are inseparable under Einsteins Theory of General Relativity)

 

 

I'm going to have to spend some more time reading  and studying about this. The only thing you have writen tht I am sure of is that the physics of black holes is beyound me. To say that gravity is nothing more than space time curvature does sound like something I might have said a while back. I also used to make statements like time is nothing more than change. I'm fairly certain that I was fairly chastized for that, and I still get confused; is it general relativity, or is it special relativity? Still I am going to step up and say that I agree with your statement about Einsteins assesment of how we should consider space and time as space/time. I am absolutly certain I was trounced right here in this very forum for stating otherwise, and have no wish to ever go there again. The rest of what you have written puzels me though, so I caint really agree or disagree with it. So, thank you once again. 

[koti]

1 hour ago, jajrussel said:

I'm going to have to spend some more time reading  and studying about this. The only thing you have writen tht I am sure of is that the physics of black holes is beyound me. To say that gravity is nothing more than space time curvature does sound like something I might have said a while back. I also used to make statements like time is nothing more than change. I'm fairly certain that I was fairly chastized for that, and I still get confused; is it general relativity, or is it special relativity? Still I am going to step up and say that I agree with your statement about Einsteins assesment of how we should consider space and time as space/time. I am absolutly certain I was trounced right here in this very forum for stating otherwise, and have no wish to ever go there again. The rest of what you have written puzels me though, so I caint really agree or disagree with it. So, thank you once again. 

In simple words, Special Relativity deals with speed of light being constant in all frames of reference and the geometries here are fairly simple. General Relativity deals with spacetime as a whole and with gravity being the distortion/curvature of that 4 dimentional spacetime construct which we exist in. General Relativity is very complex once you get deep into the details, very few people understand it fully with some of it’s implications being extremely complex - I don’t.

Oh, and time is much too complex and flexible to define it as just change. Change implies simple before, now, after and that works for us humans here on earth because we do not notice the true nature of time in our everyday lives. Time in fact is not like that... a broader, larger cosmic scale lets us understand that its relative which means it flows at different rates for different observers (frames of reference) depending on velocity and...gravity. In fact we do not even need to use large scales, satelites 100 miles above your head need to compensate for time dilation in order for  GPS’s to work. It happens as you read this.

Edited November 16, 2017 by koti

[MigL]

If the mass/energy of the Sun were to suddenly 'disappear', space-time in its vicinity would no longer have a need for curvature, and would 'spring back' to the nearly flat curvature  of intra-galactic space. The gravitational wave, caused by this springing back, would cause a 3d ripple, spreading outwards at the speed of light, with the equivalent energy of one solar mass.
This doesn't sound like quadrupole radiation, but the energy of the curved space-time has to be dissipated, and the only mechanism I know of is a gravitational wave. Maybe someone with a better understanding of GR can correct me if I'm wrong.
( furiously looking through my copy of Gravitation for  clarification )

How many solar masses disappeared in the recent collision of two black holes ?
And how distant were they ?
( IIRC, 3 solar masses 'disappeared' in the collision about a billion LY away, and the detector registered about a trillionth of an inch )

Now imagine the effects of a solar mass/energy gravitational wave at only 150 mill km.

[Mordred]

It would radiate as a quadrupole even under those conditions for example supernovas through gravitational collapse generate GW waves. If you have a copy of General Relativity a first course by Schultz it is described in his book.

Edited November 16, 2017 by Mordred