About time and absolute zero.

[silverpig]

Originally posted by: DrPizza
Here: escape velocity
Yes, there would always be a force of attraction. But, as the object is moving away, the force is decreasing.
Yes, the force of attraction never reaches zero... but that doesn't necessarily mean the velocity will ever reach zero either.

If you google for a couple more links, I'm sure one will explain it well enough for you to get a good grasp of that concept. Quite honestly, a lot of people's intuition (coupled with knowledge) is one of the reasons it's hard to grasp.

In that case your object will still always be decelerating though... the real universe is accelerating though, as if each piece of gravitationally bound matter had a little rocket on it accelerating it away from everything else.

 

[iamaelephant]

Originally posted by: silverpig
In that case your object will still always be decelerating though... the real universe is accelerating though, as if each piece of gravitationally bound matter had a little rocket on it accelerating it away from everything else.

Not really - the space itself is expanding, it's not like everything is moving away through space. It's a subtle but important difference.

 

[Netopia]

Originally posted by: Falcon39

Originally posted by: silverpig
In that case your object will still always be decelerating though... the real universe is accelerating though, as if each piece of gravitationally bound matter had a little rocket on it accelerating it away from everything else.

Not really - the space itself is expanding, it's not like everything is moving away through space. It's a subtle but important difference.

Yeah, but the net effect is the same. Things are accelerating away from each other at higher and higher velocities. I think I remember Hawking saying that it is "as if" the fabric of space were leaking into the universe between massive bodies.... he doesn't say from where, only that this is what appears to be happening. Makes me wonder if two bodies at opposite ends of the universe will eventually be eccelerating away from each other at light or near light speed in relation to one another.

Joe

 

[silverpig]

Originally posted by: Falcon39

Originally posted by: silverpig
In that case your object will still always be decelerating though... the real universe is accelerating though, as if each piece of gravitationally bound matter had a little rocket on it accelerating it away from everything else.

Not really - the space itself is expanding, it's not like everything is moving away through space. It's a subtle but important difference.

Yeah I know that, but the effect is sort of the same. I just put it in terms that would make it easier to understand.

 

[iamaelephant]

Originally posted by: Netopia

Originally posted by: Falcon39

Originally posted by: silverpig
In that case your object will still always be decelerating though... the real universe is accelerating though, as if each piece of gravitationally bound matter had a little rocket on it accelerating it away from everything else.

Not really - the space itself is expanding, it's not like everything is moving away through space. It's a subtle but important difference.

Yeah, but the net effect is the same. Things are accelerating away from each other at higher and higher velocities. I think I remember Hawking saying that it is "as if" the fabric of space were leaking into the universe between massive bodies.... he doesn't say from where, only that this is what appears to be happening. Makes me wonder if two bodies at opposite ends of the universe will eventually be eccelerating away from each other at light or near light speed in relation to one another.

Joe

Many cosmologists believe this is already happening. Of course it depends on the size of the universe but it's entirely possible that two celestial bodies that are staggeringly far apart then the light from either will never arrive. Some universes may be moving at speeds far exceeding the speed of light relative to a very far away galaxy.

 

[DrPizza]

Originally posted by: silverpig

Originally posted by: DrPizza
Here: escape velocity
Yes, there would always be a force of attraction. But, as the object is moving away, the force is decreasing.
Yes, the force of attraction never reaches zero... but that doesn't necessarily mean the velocity will ever reach zero either.

If you google for a couple more links, I'm sure one will explain it well enough for you to get a good grasp of that concept. Quite honestly, a lot of people's intuition (coupled with knowledge) is one of the reasons it's hard to grasp.

In that case your object will still always be decelerating though... the real universe is accelerating though, as if each piece of gravitationally bound matter had a little rocket on it accelerating it away from everything else.

Well, yeah. My point was simply that given the gravitational attraction between two particles and the two particles separating at some velocity, that isn't necessary for the two objects to ever come back together. In other words, ignoring everything else in the universe and only considering an object being thrown upward from the surface of the earth, for a range of initial velocities up to about 11 km/s, the object is going to eventually fall back down to the surface. The closer to escape velocity the initial velocity is, the longer it's going to take. But, if the object exceeds the escape velocity, it's never going to fall back down. That's my point (but we all knew that anyway )


Oh, and for what it's worth, someone above said something about colors being absolute (or at least yellow) "The color yellow is the frequency at which light is emitted after bouncing off a particular surface. " Without questioning where it came from before it was reflected, I'll just point out "red shift" - a person moving quickly away or toward where the yellow light was emitted would perceive a different frequency.

 

[bunnyfubbles]

Originally posted by: bendixG15

Originally posted by: Falcon39
The notion of stopping time is nonsense.........................

This is the place for questions that are not logical...
For some its stupid..for others its chicken soup.

Lots of people like chicken soup

I prefer tomato

 

[everman]

Time is an illusion, Lunch-time doubly so.

 

[CSMR]

Originally posted by: MiranoPoncho
if time were to stop

dt/dt=0?