Time Travel

Time is all relative to the individual.

So, basically my rant stands.

Vinvv got it lol

Mabrook's post makes my head hurt.

The gravitational force is just the attractive force between two objects with mass. Any one object with mass exerts an attractive gravitational force on another object with mass, so by definition Jupiter must "have gravity" due to it having mass.

The universe expands rather than collapsing into a singularity not because there isn't an overall centre of mass (and hence a gravitational attraction) but because the outward acceleration of planets (supposedly given by the Big Bang) is greater than the acceleration due to gravity caused by the centre of mass (F=ma, Newton's second law).

Or so I understand!

I wish Pluto was still a planet ;;

There should be a planet call Punana!

lol

A centre of mass exists for any system of masses. The universe is just a huge system of masses.

Jupiter has a "centre of gravitational pull" because it has a mass. Atmospheres tend to be the result of a large enough mass.

The difficulty with gravity is that people attribute it to things in everyday life, saying things like "the Earth's gravity" or "the Moon's gravity", when what they actually mean is "the gravitational force experienced by an object on the Earth's surface due to the Earth's mass". Using that more precise definition, there is no need to "hold gravity" or anything, simply because Jupiter has a mass and hence exerts an attractive gravitational force on other objects with mass.

http://en.wikipedia.org/wiki/Gravitation

it would be populated by mithra.

Don't forget that there's Dark Energy and Dark Matter etc.

Larger masses DO cause a stronger "gravitational pull".

The formula is

F = - (G * mass1 * mass2) / (displacement^2)

Negative sign because always attractive and all quantities involved are positive. F = Force, G is the Gravitational Constant, mass1 and mass2 are the two masses you are calculating the gravitational force between and the displacement is the distance between them (often denoted as r^2 since it's radial).

The universe does have a gravitational pull due to its collective centre of mass, it just doesn't exceed the acceleration due to the "Big Bang" or whatever which causes planets to move away from the "origin" so they move outwards rather than towards the centre of mass.

Indeed, there is a theoretical "big crunch" where the critical mass of the universe (the mass at which the outward acceleration and the acceleration due to the centre of gravity) is exceeded, and all will ... well, for want of a better term, go splat.

http://en.wikipedia.org/wiki/Hubble%27s_Law

Look up the "ultimate fate of the universe section" in particular. There are three possibilities to expansion: open universe, which it is thought we are currently in now, where (mass of universe) < (critical mass) and we continue to expand, a static universe where they are equal, and then the big crunch.

here, play with this:

There's no such thing as "void".

http://en.wikipedia.org/wiki/Casimir_effect

"Void" and "space" embodied as this idea of nothingness are purely human perceptions and not how things actually are. There is a gravitational attraction between every single object with mass in the entire universe and any other object with mass in the entire universe. You are exerting an attractive pull on everything else that possibly exists out there and there is no (known) way to "shield" this effect. The reason it all doesn't "float into you" is that obviously gravity isn't the only force out there and the inverse square nature of the attraction (~ 1/(r^2)) means that displacement is hugely instrumental in the magnitude of this force.

The universe continues to expand because the initial acceleration provided by the Big Bang (current theory) overcomes the gravitational force exerted by the sum total of the universe's mass. Once this mass reaches a limit (the critical mass), this may/will change.

The plates thing is an analogy. The tl;dr version is that in "empty" space, there are particles fading in and out of existence in line with the Uncertainty Principle connecting energy and time.

I dunno if I'm being dumb, but that's a Feynman diagram which describes transitions between quantum states and the probabilities thereof. The y-axis is time.

Time isn't nonexistant in empty space and I don't see how time=gravity? I could just be doing dumb again; studying Physics has largely taught me how little I know about it, but I don't understand why time is gravity by definition?

The real question should be Does yesterday still exist today or has it gone forever.

The real question is why did your "question" not end in a question mark?

Also, why is the d in "Does" capital?

Because the keyboard is broke and it doesnt have a question mark any more

this is kinda neat and seemingly relevant.

link

This doesnt make sense because you can reverse gravity but it doesnt reverse time.