Physics Question

[TheOriginalTonkaToy]

Tonka, I follow your argument most of the way but I'm struggling with the following: Your explanation makes it sound like the gravitons beaming towards the Earth in space can have a holding effect on their own with no body to pull against. In other words right up to the point that the last graviton arrives at the Earth the Earth would be held by those gravitons. But how can this be? Do the two bodies held together by gravity not rely on each other for stability. More akin to a rope holding two bodies together. Cut the rope holding the Sun and earth together and the effect would be instant. One part of the rope would fly off with one of the bodies and the other with the other. The rope could not hold either in place on it's own.

Think of the rope being shaken to produce a wave that travels along it, now make that rope very very long stop shaking the end suddenly. It'll take a while for the pre-existing waves already on the rope to cease and the rope to become still. That's a reasonable analogy

 

[TheOriginalTonkaToy]

No folks I've got it right. The sun's mass distorts space and creates gravity. Take that gravity away and what happens? According to you lot - nothing happens. So what role has the sun played in holding the planets in place all these billions of years? None according to you.

The question is what would happen if the sun disappeared - so what would happen?

Nobody has said nothing happens - keeping on saying it ad nauseum isn't going to change that. What's been said is that there's no immediate effect on the Earth.

Mass distorts the fabric of space-time - the analogy of a dent in a rubber sheet will do for this. Remove the mass of the Sun and the fabric of space-time will rebound but that rebound will occur at a finite speed - not instantaneously. Instantaneous change is not permitted at the physical level - maximum velocity permitted is the speed of light. Therefore it will take just over 8 minutes for the rebound to reach Earth.

 

[joe-90]

I'm right and I know that I'm right.

You cannot have mass without gravity.

Therefore you cannot have gravity without mass.

They cannot be separated.

If the sun were to disappear instantly - then so must the gravity associated with it.

If that isn't true - then you have gravity in the universe without corresponding mass - and that isn't possible.

If you think that it is - then give me one example of gravity without mass in our entire universe. Just one will do.

Gravity and mass are inseparable.

If you cannot give me an example of gravity without mass - then you lose.

 

[TheOriginalTonkaToy]

No folks I've got it right. The sun's mass distorts space and creates gravity. Take that gravity away and what happens? According to you lot - nothing happens. So what role has the sun played in holding the planets in place all these billions of years? None according to you.

The question is what would happen if the sun disappeared - so what would happen?

Wow, has Joe completeley misunderstood the question which everyone else seems to understand?

I have posted a link which shows where the speed of gravity has been measured.

If the Sun were to go, how soon, gravitationally speaking, would we know about it? As the effect of gravity takes times to reach us, as discussed, travelling at the speed of light, the change in gravity will take effect approx 8 1/2 minutes after the sun has disappeared. What do you not get Joe?

No one has stated that the Earth will keep on orbiting an empty space forever, changes in gravity take time to take effect over any distance, the further away you are, the longer it takes to reach you. The Earth will fly off in a straight line 8 1/2 minutes after the Sun has disappeared.

Not in a straight line - remember there are other masses and hence gravitational sources in the Solar system

 

[Astartes]

I'm right and I know that I'm right.

You cannot have mass without gravity.

Therefore you cannot have gravity without mass.

They cannot be separated.

If the sun were to disappear instantly - then so must the gravity associated with it.

If that isn't true - then you have gravity in the universe without corresponding mass - and that isn't possible.

If you think that it is - then give me one example of gravity without mass in our entire universe. Just one will do.

Gravity and mass are inseparable.

If you cannot give me an example of gravity without mass - then you lose.

Are you a simpleton? The question is hypothetical in the extreme and has been answered. Looking for bodies again you pie?
There are no examples of what the O.P's question postulates.
oh and see bold: Aye it is.

 

[joe-90]

Of course there are no examples in our universe as the question isn't possible in our universe so there is no reason that the answer is possible in our universe.

FFS haven't you grasped that yet.

If you are looking for a simpleton - find the nearest mirror.

Mass without gravity in impossible.

Gravity without mass is impossible.

Take away the mass instantly - and you take away gravity instantly.

That is a fact - live with it.

It isn't possible in our universe but that isn't the question.

You lose.

 

[chapeau]

Have you started throwing things yet?

Please tell us the next thing to hit the wall is your computer...

 

[joe-90]

Sorry - you lose.

 

[chapeau]

Well this isn't a competition but even if it was it doesn't bother me if I lose. Always happy to admit when I'm wrong, it's a strength not a weakness.

I've been educated in science to a level which you could only dream of and been trained to evaluate evidence in a dispassionate way. If I acknowledge I'm wrong then that's fine, because that makes me right. There is no need to acknowledge I'm wrong on this thread because, well, I'm not.

In summary I suppose, unlike you, I don't have an inferiority complex. That's cos I'm a lot better at this stuff than you, but unlike you really don't need to prove it

 

[noseall]

Joe is never wrong.

 

[joe-90]

Well this isn't a competition but even if it was it doesn't bother me if I lose.

Well that's good cuz you just lost.

 

[joe-90]

I've been educated in science to a level which you could only dream of

Oh FFS stop bragging. You can't even win an argument on a DIY forum - how fookin clever are you in the real world?

 

[TheOriginalTonkaToy]

I'm right and I know that I'm right.

You cannot have mass without gravity.

Therefore you cannot have gravity without mass.

They cannot be separated.

If the sun were to disappear instantly - then so must the gravity associated with it.

If that isn't true - then you have gravity in the universe without corresponding mass - and that isn't possible.

If you think that it is - then give me one example of gravity without mass in our entire universe. Just one will do.

Gravity and mass are inseparable.

If you cannot give me an example of gravity without mass - then you lose.

You clearly don't understand your own question which is a pretty poor position to start a debate from. If you don't understand that the speed of light is a given maximum for physical effects in the universe then you don't understand physics. I can recommend a decent science foundation course for you if you like.

By the way, as you were at pains to point out earlier, this is a thought experiment, not a real one. You can't make mass suddenly disappear without violating some fundamental laws so we're talking about a hypothetical albeit impossible scenario. Of course you need mass for gravity but gravity is a force and forces obey physical laws. Now think again.

Oh and repeating 'I win, you lose' over and over doesn't make it true...

 

[hansthebear]

Urgh, more high school level science lessons required.

A bodies mass is what it is.

A bodies WEIGHT will vary due to the gravity acting on its MASS

W = mg

Where g is the gravitational constant, which on earth is about 9.8 meters per second squared

m is mass in kilograms

And W is weight in NEWTONS.

Aaaaaaaaarrrrghhhhhhh

 

[joe-90]

I'm right and I know that I'm right.

You cannot have mass without gravity.

Therefore you cannot have gravity without mass.

They cannot be separated.

If the sun were to disappear instantly - then so must the gravity associated with it.

If that isn't true - then you have gravity in the universe without corresponding mass - and that isn't possible.

If you think that it is - then give me one example of gravity without mass in our entire universe. Just one will do.

Gravity and mass are inseparable.

If you cannot give me an example of gravity without mass - then you lose.

You clearly don't understand your own question which is a pretty poor position to start a debate from. If you don't understand that the speed of light is a given maximum for physical effects in the universe then you don't understand physics. I can recommend a decent science foundation course for you if you like.

By the way, as you were at pains to point out earlier, this is a thought experiment, not a real one. You can't make mass suddenly disappear without violating some fundamental laws so we're talking about a hypothetical albeit impossible scenario. Of course you need mass for gravity but gravity is a force and forces obey physical laws. Now think again.

Oh and repeating 'I win, you lose' over and over doesn't make it true...

It does if you cannot answer this simple question:

Can gravity exist without mass?

If the answer is no - then I win.

When the mass of the sun disappeared (not possible in our universe) then either it took its gravity with it or left it behind.

Either gravity and mass are inseparable or they are not.

The speed of light has fook all to do with it in this imaginary universe.

The only relevant question is:

Can gravity exist without mass. I say no - you say yes.

I'm asking you to give me just one example of gravity without mass in our entire universe and I'll accept that I am wrong and you are right - but it works both ways. If you cannot - then by default I must be right.