Escape velocity can't be real!

[cuttergirl]

*steadys myself for this question. Going to be some DIFFICULT MATH!*

 

 

OK, so in this question, I am going to attempt to explain to you that an ever expanding universe is impossible, and that another big-bang is unavoidable!

 

I'll do it in steps, since I grow bored easily. Astin, you can help me with this one since you know what I want to do.

 

 

If anyone else wants to help with the math on this, I welcome you too, but only if you understand what im doing, and dont guess! Corrections are good too!

[insane_alien]

escape velocity equations are nowhere near difficult math. just a bit of basic calculus is all you need.

[John Cuthber]

Conceptually, escape velocity is quite easy. You don't need the maths to understand that an object falling to (for example) Earth will only end up with a finite velocity when it hits the ground no matter how far it falls from (because once yo are a long way off the extra enery gained from falling tends to zero).

If you reverse that process and throw something faster than that finite velocity, it escapes.

 

"Astin, you can help me with this one since you know what I want to do."

No, I'm afraid that Astin can't help you unless Astin can rewrite the laws of physics..

[mooeypoo]

I'm still waiting for the groundbreaking concept, regardless of how hard the math is, I'd love to know how escape velocity is related to the expansion of the universe or to a recurring big bang, and how such a thing can be proven..

 

Will the OP please continue her thought?

[DJBruce]

I discussed Cutter's and Princess' theory wit them on IRC two nights ago. Their theory is similar to the big crunch, although they did not expressly use that name. They believe that eventually universal expansion will stop, and slowly gravity will pull everything back together. Everything will eventually be compressed into a singularity and then another big bang will occur, saving us from the heat death of the universe. This was what their theory appeared to be, although they didn't provide any proof or evidence for it.

 

As for the what escape velocity has to do with the expansion of the Universe, I would speculate it might come from something similar to this passage from Wiki:

 

"If the universe is finite in extent and the cosmological principle (not to be confused with the cosmological constant) does not apply, and the expansion speed does not exceed the escape velocity, then the mutual gravitational attraction of all its matter will eventually cause it to contract."

 

But to be honest I have no idea what this means.

[Baby Astronaut]

...the extra enery gained from falling tends to zero).

What's that mean precisely? I looked it up but found no leads.

[insane_alien]

say you go up 1000km and fall. you would have a certain amount of kinetic energy. if you go up double the distance you will maybe only have 1.9 times the kinetic energy when you hit the ground. double the distance again and it is 2.7. at infinity you will have a finite energy when you hit the ground.

 

these numbers in noway reflect the gravitational pull of earth, they are merely an example.

 

the velocity gained from falling is asymptotic to the escape velocity. this is due to gravity following an inverse square law with distance.

[swansont]

What's that mean precisely? I looked it up but found no leads.

 

[math]\Delta KE = -\Delta PE[/math]

 

[math]PE = \frac{-GMm}{r}[/math]

 

the terms tend to zero for large r

[the tree]

psssst... I don't think they're coming back.