If the sun suddenly dissapeared.

In summary, there is a hypothetical situation about the sun disappearing and the Earth receiving light for 8 minutes before the gravitational wave hits and causes the Earth to fall out of orbit. The question is whether any experiments have been done to confirm that a smaller object would not move until the light from the bigger object had disappeared. It is also asked if there is another force holding the Earth with the Sun, but it is confirmed that the only significant force is gravity. The conversation then shifts to discussing the difference between laws governing the micro and macro scale, but it is concluded that there is no real difference and quantum effects can manifest at the macro level. There is also a comparison made to a pebble dropping in water and potentially affecting the space-time around
  • #1
Willowz
197
1
I have a question about this known hypothetical situation. Einstein asserts that once the sun vanishes we would still receive light for 8 min. Then at almost/same time when the sky goes dark, the gravitational wave hits Earth and we would fall out of the earlier orbit around the sun.

Some questions about the situation above.

Have any experiments of this type been done? Confirming that a smaller object would not move, until the light from the bigger object had dissapeared?

And would it be possible that once the sun disappeared the Earth could move, even though the gravitational wave did not reach the Earth?
 
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  • #2
The Sun can't just "disappear". Conservation of energy and momentum prevents that. We can't even move it "out of the way" fast enough, it would have to be accelerated close to the speed of light, we don't know how to do that.
 
  • #3
Some relevant material here: http://www.lightandmatter.com/html_books/genrel/ch08/ch08.html#Section8.1

The basic answer is that we have excellent evidence that gravitational waves exist, and that they carry energy, but we don't have any direct, model-independent evidence that disturbances in the gravitational field travel at c.
 
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  • #4
It's a hypothetical situation or a thought experiment if you will.
bcrowell said:
The basic answer is that we have excellent evidence that gravitational waves exist, and that they carry energy, but we don't have any direct, model-independent evidence that disturbances in the gravitational field travel at c.
I believe they do exist. But what I have in mind is if there are any other force holding the Earth with the Sun? If there is another force, then it would be noticable in such a situation.
 
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  • #5
Willowz said:
But what I have in mind is if there any other force holding the Earth with the Sun?

No, the only significant force on the Earth is gravity.
 
  • #6
Willowz said:
It's a hypothetical situation or a thought experiment if you will.
Well, you did ask if any experiments had been done...

Willowz said:
I believe they do exist. But what I have in mind is if there are any other force holding the Earth with the Sun? If there is another force, then it would be noticable in such a situation.
I'm almost afraid to ask but what makes you think there might be another force than gravity?
 
  • #7
DaveC426913 said:
Well, you did ask if any experiments had been done...
My quote:
Willowz said:
Have any experiments of this type been done?
"This type" in my lingo means something similar, something like the Gravity Probe B experiment. But I think it should be better be called a "thought experiment". Since such a situation is not possible.
I'm almost afraid to ask but what makes you think there might be another force than gravity?
I don't know. I'm not good at sci-fi at the moment.
 
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  • #8
Willowz said:
I don't know. I'm not good at sci-fi at the moment.
but something made you ask the question.

Anyway, no. There are no other attractive forces known or hypothesized (though there are some repulsive ones, such as the solar wind).
 
  • #9
I don't know if I should be concentrating on the micro world with this logic or in the macro. But if it can be shown that a planet would move(even the smallest movement), then that could be a stepping stone for some further explanation between the difference of laws governing the micro and macro scale.
 
  • #10
Willowz said:
I don't know if I should be concentrating on the micro world with this logic or in the macro. But if it can be shown that a planet would move(even the smallest movement), then that could be a stepping stone for some further explanation between the difference of laws governing the micro and macro scale.

I completely don't follow.

I'm not sure what micro vs. macro has to do with anything, but more importantly, it sounds like you're trying to invent a phenomenon out of whole cloth.

Since there are no attractive forces acting between Sun and Earth other than gravity, nor is there any reason to think so, nor is there any reason to think the Earth does or would move ...

... what is the origin of the question?


In the same sense (taken to a slightly more absurd level):
Q: It is possible that Neptune is a unicorn? If it were, it should have a horn. Has anyone looked to see if it has a horn? Because of it did, that would be evidence that it was a unicorn.

A: Um, why do you think Nepture might be a unicorn in the first place?
 
  • #11
Wait. In re-reading your post, I realize that the whole Earth-Sun thing is not the crux of your question. This is the crux of your question:
Willowz said:
...some further explanation between the difference of laws governing the micro and macro scale.

You're trying to sort out the quantum world versus the marco world.


There's no real difference. Quantum effects (such as wavefunction frequency) manifest as inversely proportional to the size/mass of the object. A 100kg human has a wavefunction just like a proton does, it's just that the frequency is so high as to be irrelevant at the macro scale.

A human can tunnel through a wall "just" like an electron can, but the probability is inversely proportional to the number of particles in the human.
 
  • #12
Ok, so I will try in other words. If I drop a pebble into the water, I will see waves forming. If I am in the water and a pebble falls. I can hear the sound of the pebble falling into the water sooner than the waves reach me, furthermore because I am in the water the pebble minimally affected me. Because there was a displacement of water.
 
  • #13
No, I think it would be wrong to say that the pebble directly affects me while in the water. I think the pebble might affect the space-time around me. Though I do think if it can somehow indirectly have an influence on me.
 
  • #14
DaveC426913 said:
Wait. In re-reading your post, I realize that the whole Earth-Sun thing is not the crux of your question. This is the crux of your question:


You're trying to sort out the quantum world versus the marco world.


Yes, I think you are right. But I don't know where now.
 

Related to If the sun suddenly dissapeared.

1. What would happen to Earth if the sun suddenly disappeared?

If the sun suddenly disappeared, Earth would no longer receive sunlight and heat from the sun. This would cause the temperature to drop rapidly, leading to an extreme drop in temperature and eventually causing all life on Earth to freeze and die.

2. How long would it take for the effects of the sun's disappearance to be felt on Earth?

The effects of the sun's disappearance would be felt almost immediately on Earth. Within 8 minutes, the sunlight that usually reaches Earth would be gone. However, it would take a bit longer for the temperature to drop, as the Earth's atmosphere and oceans would still retain some heat initially.

3. Would Earth still have gravity if the sun disappeared?

Yes, Earth would still have gravity if the sun disappeared. The sun's gravity is not the only force that keeps Earth in orbit, as the Earth's own momentum and inertia also play a role. However, the orbits of the planets would be affected and may eventually become unstable without the sun's gravitational pull.

4. Could we survive if the sun disappeared?

No, it is highly unlikely that any form of life on Earth would survive if the sun suddenly disappeared. The extreme drop in temperature and lack of sunlight would make it impossible for any living organism to survive.

5. Is it possible for the sun to suddenly disappear?

No, it is not possible for the sun to suddenly disappear. The sun is a stable star and its sudden disappearance would go against the laws of physics. However, it is possible for the sun to eventually die out or explode in a supernova, but this process would take millions of years.

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