We have this fictional solar system not unlike our own, obeying all the usual physical requirements as ours.

Everything is great no problem present then the star starts to dim, it's output reduces say by 20 %

What happens to the fictional solar system?

What has happened to the strength of gravity of the star?

I would think that as the star dims ( cools ) it's gravitational strength would increase thus pulling all objects towards it.

So it's light and EM emmissions have diminished and the overall outcome is a strengthening of the gravitational pull towards it.

I heard some where that even a black hole emits and this leads me to think that if it didn;t the black hole would become a true singularity. ( as in no countering force available thus colapsing the universe entirely)

Thinking in terms of a "closed shop" or "closed universe" the reduction in light or EM could be also a reduction in the gravitational mitigation of the primary gravity of the star.

Could Light and other emmisions be the universal constant simply by default?

Originally posted by Quantum Quack
We have this fictional solar system not unlike our own, obeying all the usual physical requirements as ours.

Everything is great no problem present then the star starts to dim, it's output reduces say by 20 %

What happens to the fictional solar system?

What has happened to the strength of gravity of the star?

Nothing


I would think that as the star dims ( cools ) it's gravitational strength would increase thus pulling all objects towards it.

So it's light and EM emmissions have diminished and the overall outcome is a strengthening of the gravitational pull towards it.



No there is no such relationship btween a stars gravity and its light ouput.

The only luminousity/ gravity relationship is that more luminous stars are more massive, but this is just because more massive stars burn their nuclear fuel up faster.

Janus if a star actually dimmed in it's emissions by 20% what would cause that. The star to dim.

Isn't it theorised that the star would grow in size or something ?

Originally posted by Quantum Quack
Janus if a star actually dimmed in it's emissions by 20% what would cause that. The star to dim.

Isn't it theorised that the star would grow in size or something ?

A star will dim when its nuclear output decreases. Also because of this, it will begin to contract until helium fusion takes over. When this happens, enough energy is released to expand only the outermost layers) of the star forming a red giant.

How would the gravity of a red giant differ from the original state?

The emissions of course have changed considerably

The mass would still be about the same, so there wouldn't be much chance in gravity.

Originally posted by Quantum Quack
How would the gravity of a red giant differ from the original state?

It would have slightly decreased. Why? What are u thinking now?!!!

Originally posted by John Connellan
It would have slightly decreased. Why do you say that?

Originally posted by Nasor
Why do you say that?

Gravity is proportional to mass. The mass of the star would have decreased.

Is Janus correct in stating
No there is no such relationship btween a stars gravity and its light ouput.
???

I would have thought to the contrary.
That there is a direct reationship between gravity and emissions.

Isn't temperature and weight also directly related?

Originally posted by Quantum Quack
Is Janus correct in stating

???

I would have thought to the contrary.
That there is a direct reationship between gravity and emissions.

Isn't temperature and weight also directly related?

Where did you get that idea?

Originally posted by John Connellan
Gravity is proportional to mass. The mass of the star would have decreased.

Are you talking about the mass decrease due the the burning of nuclear fuel over the lifetime of the Star?

In this case a star like the sun would only lose about .027% of its mass in the in few billion years from now until it swells into a red giant.

If you are talking about just during the expansion phase, there is no appreciable mass loss during this stage.

Originally posted by Janus58
Are you talking about the mass decrease due the the burning of nuclear fuel over the lifetime of the Star?

Yes I am, but Im also talking about solar flare emissions etc.


In this case a star like the sun would only lose about .027% of its mass in the in few billion years from now until it swells into a red giant.

So what?!

Originally posted by John Connellan




So what?!

The point is that mentioning it without the qualifier merely confuses the issue for someone (QQ), who is already struggling under some misconceptions. It could lead him to believe that just the process of expansion decreases the gravity of the star.

Originally posted by Janus58
The point is that mentioning it without the qualifier merely confuses the issue for someone (QQ), who is already struggling under some misconceptions. It could lead him to believe that just the process of expansion decreases the gravity of the star.

Well the thing is, the force of gravity one feels at the surface of a red giant is not as strong as that of its original state. This is because gravity acts from the center of the star. This leads to a lot more emission activity from the surface than it did in its original state.

The force of gravity that you feal doesn't depend on the density of the star. It depends on the distance between you and the star and the mass of the star.

Originally posted by Redrover
The force of gravity that you feal doesn't depend on the density of the star. It depends on the distance between you and the star and the mass of the star.

Nobody said anything about density. It doesn't depend on the distance from the star as such, it depends on r (r^2 to be exact)

Thank you Janus and others for attempting to clear up any misconceptions you feel I am working with.

The question I wanted to ask was really in an absolute sense I guess.

If the sun stops shining, in other words cools to the point where it emits no visible light, how would it's gravity be different to now?

At the moment I woudl assume according to what I have read that the sun's attraction (gravity would be much greater than now ( if it cools to the point of not shining/emitting visible light?

Another aspect relevant.

If something hits an object at the speed of light one would expect quite a significant impact on that object.

The suggestion being that if light does in fact travel at it's speed then it's shere velocoty would have a significant impact on it's collision point.

And in this sense could very well be the universal constant.

( keeping in mind that the backdrop to all this is the vacuum of space)

Originally posted by Quantum Quack
Thank you Janus and others for attempting to clear up any misconceptions you feel I am working with.

The question I wanted to ask was really in an absolute sense I guess.

If the sun stops shining, in other words cools to the point where it emits no visible light, how would it's gravity be different to now?

At the moment I woudl assume according to what I have read that the sun's attraction (gravity would be much greater than now ( if it cools to the point of not shining/emitting visible light?

No, it wouldn't. Ignoring the mass loss due to fuel burning, (and the loss of material when the Red giant blows off its outer layers and forms a planetary nebula.) the force of gravity of the sun would not change one iota. (Imagine that the sun's nuclear fusion process just suddenly stops, and the sun begins to cool. The Sun's gravity would stay essentially unchanged as it dimmed)



Another aspect relevant.

If something hits an object at the speed of light one would expect quite a significant impact on that object.

The suggestion being that if light does in fact travel at it's speed then it's shere velocoty would have a significant impact on it's collision point.

And in this sense could very well be the universal constant.

( keeping in mind that the backdrop to all this is the vacuum of space)

The force of impact is not due to sheer velocity, it is due to momentum. Classically, momentum is velocity times mass. thus a massive slow moving object can have a large momentum, and thus a greater force of impact than a less massive, fast moving object.

Light has no mass in the classical sense, but it does have momentum, and this momentum is tied to its frequency. But the momentum of light is very small. At the distance of the Earth from the Sun this works out to about a pressure of .000000094 pounds per square ft. This is not much of an impact. (air pressure alone is 2016 pounds per square ft.)

Basically just repeating what others have already said:

Originally posted by Quantum Quack
Thank you Janus and others for attempting to clear up any misconceptions you feel I am working with.

It is not just something we feel. They ARE misconceptions because they run contrary to consistent, well-documented, validated by experiments, data. The kind of data we usually refer to as facts.

The question I wanted to ask was really in an absolute sense I guess.

If the sun stops shining, in other words cools to the point where it emits no visible light, how would it's gravity be different to now?

There is no direct connection between the sun's emission and it's field of gravity.

At the moment I woudl assume according to what I have read that the sun's attraction (gravity would be much greater than now ( if it cools to the point of not shining/emitting visible light?

No. You must have misunderstood something. If you can point to the exact information that made you come to that assumption, we might be able to clear it up.

Another aspect relevant.

If something hits an object at the speed of light one would expect quite a significant impact on that object.

An object cannot attain the speed of light. But an object impacting at near the speed of light will give a very large impact, yes.

The suggestion being that if light does in fact travel at it's speed then it's shere velocoty would have a significant impact on it's collision point.

Light is not an object. There is no reason to speculate about this, we can measure both the speed and impact of light.

And in this sense could very well be the universal constant.

( keeping in mind that the backdrop to all this is the vacuum of space)

Quite. The speed of light in vacuum (c) IS indeed a universal constant.

QQ, you are out on a limb here (and with some of your other questions). This sounds a bit condescending, but it is not meant that way: Your knowledge and understanding of physical phenomenon is somewhat sketchy (to put it mildly), and I would suggest that you refrain from making any conclusions and theories based on it. I can see from your mode of arguing in this and other threads that you have some ideas and theories that you are reluctant to abandon, in spite being faced with contradictory facts.

Study, and ask questions. Once you know more, and understand more, your ideas will be based on more solid ground.

Hans

Mrc hans and Janus and others thanks for your comments and yes my source reads were read badly. I just reveiwed what I read so many years ago and I understand the error that I am trying to get others to accept.

I shall do better reading first before I post again, thanks

Don't mention it :). Everybody makes mistakes, it is how you handle them that matters.

Without asking, you get no answers.

Hans