Why two mass attracts each other?

Discussion in 'Physics & Math' started by hansda, Mar 19, 2013.

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1. Russ_WattersNot a Trump supporter...Valued Senior Member

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Irrelevant/choice. If they went south the thought experiment works the same.

It is posts like this that make me doubt your seriousness.

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3. eramSciengineerValued Senior Member

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So that's how MJ does it.

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5. Motor DaddyValued Senior Member

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I don't know, how would I measure that? Are you advocating two tests, one without the sun present and one with the sun present?

I mean, basically the sun is a slow bomb going off, and you are trying to pretend that the force is basically nonexistent.

You can spin it as many ways as you care to, the bottom line is the sun is pushing the earth away from the sun's core over time. The force of the sun is pushing the planets away.

Last edited: Apr 17, 2013
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7. originHeading towards oblivionValued Senior Member

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If all the planets and asteroids were to fall into the sun, it's mass would increase by about 0.2%. The minimum mass needed to make a black hole is 3 to 4 solar masses.

8. originHeading towards oblivionValued Senior Member

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What do you think it is about an explosion that exerts a force?

A fire is basically a slow explosion - how much force do you feel from a fire?

9. eramSciengineerValued Senior Member

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@Motor Daddy

The Sun isn't actually "on fire". But whatever non-grav force it exerts on Earth is still negligible.

On a side note, firestorms can "suck you in".

10. Markus HankeRegistered Senior Member

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Because this is just an analogy to illustrate the principle of why they approach each other if they both walk north. Remember that "north" corresponds to "the future".

The analogy applies only to two isolated bodies under the influence of their mutual gravity, and is designed to demonstrate why they approach each other. It cannot be applied to any other scenario, hence also not to the universe as a whole.

11. Russ_WattersNot a Trump supporter...Valued Senior Member

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Motor Daddy, it is clear to me that you don't know about this subject so you are making this up as you go along, believing you are smart enough to figure it out. That takes an extraordinary lack of self-awareness. This stuff took nobel prize winners years to figure out, so since you are not a nobel prize winner, you must accept that you can't figure this out on your own and instead learn it.
Sure. Fortunately, experiments have already been done and the amount of radiation pressure quantified. It is a well established phenomena. http://en.wikipedia.org/wiki/Radiation_pressure
This shows a profound lack of understanding of how bombs work and why they produce force (pressure). Bombs require a medium to transmit their force (air, water, objects). Out in space, there is no medium, so no force.

In any case, that's different from radiation pressure anyway.
I'll put it simply: if the effect were significant, our theories of gravity wouldn't work. We wouldn't have been able to send space probes where we wanted them to go.

You need to start learning stuff instead of making it up as you go along. This issue though is such an easy one that it makes it difficult to believe you are serious when you propose such things.

12. Motor DaddyValued Senior Member

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Russ, As Adam Savage would say, "I reject your reality and substitute my own."

13. eramSciengineerValued Senior Member

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He was being sarcastic, and I hope you are too. I hope...

14. wellwisherBannedBanned

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The reasons why two masses attract each other can be inferred from basic principles and observations.

(1) Although energy travels at the speed of light, mass cannot travel at the speed of light according to special relativity.

(2) According to E=MC2, energy and mass are both types energy, with mass condensed/confined energy.

(3) According to general relativity, as mass accumulates due to gravity space-time contracts.

(4) Observation shows there is a preponderances of mass to energy conversion in our current universe; fusion. The preponderance of mass formed very early in the universe.

(5) The speed of light is only reference that is the same in all references.

As such, mass attracts mass because this helps moves confined/condensed energy, back in the direction of the speed of light reference. Two masses may not reach the speed of light by themselves, but this direction of the mass helps set the stage because space-time will nevertheless contract in the direction of the speed of light reference. The process will release heat and then mass burn via fusion; back to C. The black hole approaches the limit bring all the mass back toward C; point space-time.

15. eramSciengineerValued Senior Member

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Woah, that's new. You could discuss this with quantum_wave

16. Markus HankeRegistered Senior Member

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Firstly, it doesn't contract, it curves. In general that is not the same thing.
Secondly, space-time does not curve due to gravity, but the curvature is gravity. Again, there's an important difference here.

17. Russ_WattersNot a Trump supporter...Valued Senior Member

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Doubt it.

More to the point, I'm quite sure MD doesn't know what the reality is that he's rejecting!

18. eramSciengineerValued Senior Member

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He thinks we live in the Matrix, so any reality is possible.

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Lol

19. billvonValued Senior Member

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That's why he falls over all the time. But he figures that's due to relativity being wrong.

20. AlphaNumericFully ionizedRegistered Senior Member

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It is very important to be precise about these things. When a bomb goes off the reason debris is thrown outwards is because the rapid heat increase causes gases created by the burning to expand, pushing things outwards. The Sun doesn't burn like that, the process is nuclear, not chemical. The Sun emits a solar wind and also the enormous amount of light does indeed have a small outward pushing effect, as light carries momentum (hence notions such as the solar sails). The effects of these add up over time, it is the solar wind which has stripped Mars of its atmosphere while the Earth's magnetic field protects ours from being 'blasted' away.

When considering questions about whether or not the Sun's solar wind and light pressure is pushing planets away also requires you to consider other effects of a similar magnitude. Tidal braking, both in terms of the Moon on the Earth and the Sun on the Earth, is important (a year used to have 400 days back during the age of the dinosaurs, tidal braking has slowed the Earth's rotation). Perturbations in orbits due to highly complicated nonlinear interactions from a multi-body gravitational system. Perhaps even gravitational radiation emissions caused by orbital mechanics, which causes orbits to shrink. So your 'bottom line' is at best unsupported.

21. RitaRegistered Member

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I don't know what I am suppose to become aware of, because I don't understand the terminology of the words yet, but I was able to get two dots to collide, and they became one. What I read a couple of days ago, said the planets had a long time to clear their paths. Seeing the two dots collide and become one seems to give meaning to what I read. But I feel so bloody uneasy with things moving eternally. It takes no energy to move through space? Yet we are caught in orbits because of gravity, and the gravity doesn't suck us in to the sun, making a Black Hole as Hansda suggested, why? What is holding us apart? There can not be just gravity. Oh dear, brain melt down.

Hansda says it is our orbits that maintain us where we are, but is gravity an energy? Is momentum an energy? What is the source of this energy? Like if our orbit is resisting the force of gravity, that requires energy, right? Some claim there is a particle that causes gravity. Is a moving planet its own energy? Like I said brain melt down. I am having trouble getting my brain wrapped around these thoughts?

By the way, a dot moving across a black screen seems pretty miraculous to me. Maybe if I could understand how the computer does this, I could understand our reality? I swear, this technology totally boogles my mind. I am convinced we can not know reality without completely reprogramming our brains. I don't think education has come close to preparing children to understand reality of the future. I need to start a new thread for that question.

22. hansdaValued Senior Member

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Orbit is due conservation of energy where "kinetic energy" and "potential energy" of a mass is being conserved around a "central mass". In the solar system the "central mass" is the Sun. "Potential energy" of a mass is due gravitational force."Kinetic energy" is due motion of the mass. When PE converts into KE, "gravitational force" generates.

Had there been no gravity, the planets would have escaped our solar system. It is due to gravity, that our solar system is intact.

23. hansdaValued Senior Member

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Do you imply that it is possible to go back to "the past"?

Do you think our "solar system" is isolated from the universe?

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