Gravity?

[Omega Ohm]

Originally posted by: cquark

Originally posted by: Generic Moniker
Seeing that no one has measured a graviton, I would hardly characterize the above communication as fairly easily.

Fair enough, LIGO isn't an easy detector and artificially creating detectable gravity waves would be even harder.

A graviton wouldn't travel any faster than light. You don't necessarily have to find a graviton, which is impossible you can simply measure gravity's time of effect. For instance, it could possibly be measured with the moon and the tides. Einstein put the speed of gravitational effects right at the speed of light.


Here's a more interesting one.

All matter exerts gravitational influence on all other matter in the universe. It is possible the distance between two bodies could eventually become so great the rate of spacial expansion between them becomes too much for even light to to ever reach it's destination. Example, light travels at 299,792,458 m/s. With enough distance between the objects, expansion could reach a rate faster than 299,792,458 m/s so light sent between the two bodies could literally never reach other.

What implication does that have for gravity?

 

[flamingspinach]

Correct me if I'm wrong, but isn't gravity at that kind of distance insignificant?

Question: How is the universe so uniform if during the Inflationary Period, the universe was expanding faster than the speed of interactions between matter? If interactions between matter were not possible at this time (at least across the entire universe), how has the current equilibrial state of uniform galaxies spread across the universe occurred?

-fs

 

[wjgollatz]

Originally posted by: Joerg
Hmm so is it scientifically shown that there was nothing before the big bang? I kind of find it hard to believe that the big bang is the beginning of everything. Ive always held the opinion that the big bang was the result of all the matter in a previous universe colliding into a massive ball or somthing like that and finnally culminating into a massive release of energy and matter. Sort of black holes eating each other until everything is all in one. Not saying im right just wondering.

And thanks for all the info.

You want to read about Super String Theory and branes/membranes - that teory should answer your question.

 

[wjgollatz]

Originally posted by: flamingspinach
Correct me if I'm wrong, but isn't gravity at that kind of distance insignificant?

Question: How is the universe so uniform if during the Inflationary Period, the universe was expanding faster than the speed of interactions between matter? If interactions between matter were not possible at this time (at least across the entire universe), how has the current equilibrial state of uniform galaxies spread across the universe occurred?

-fs

I'm not sure of the poster who said that - but I coincidentally just finished reading a summary of the inflationary period - during that period - certain types of matter began to form in sequences - for instance quarks then gluons - for instance - there was no light - because the universe was so dense... Not all interactions we see today could have occurred at all times during inflation.

 

[silverpig]

Originally posted by: flamingspinach
Correct me if I'm wrong, but isn't gravity at that kind of distance insignificant?

Question: How is the universe so uniform if during the Inflationary Period, the universe was expanding faster than the speed of interactions between matter? If interactions between matter were not possible at this time (at least across the entire universe), how has the current equilibrial state of uniform galaxies spread across the universe occurred?

-fs

Random distribution of matter due to quantum mechanical effects

 

[Omega Ohm]

Originally posted by: flamingspinach
Correct me if I'm wrong, but isn't gravity at that kind of distance insignificant?

-fs

Practically insignificant but theoretically very important as to the nature of gravity itself.

 

[JF0603]

this question is just like saying "if there waws a hole in the ozone + atmosphere would i be able to jump to the moon

 

[imported_kouch]

yes the fundamental confusion seems like this idea that science is somehow denying that anything existed before big bang. The point is not that there was nothing before the big bang, the point is that "before big bang" has no meaning in the context of our current universe.

 

[element]

Originally posted by: cquark

Originally posted by: Joerg
Ok i understand that time for this universe begins after the bigbang and there for from our universes perspective there is no before the big bang becuase that is the point of orgin for time and space. But what i cant understand is any scientific explanation of why there can be no before big bang from any perspective.

Your reasoning still sounds like it's based on the idea that spacetime is something separate from the universe, so you could just change your coordinate system or move outside of the universe to observe its formation. The problem is that there is no outside.

Well not as far as you know. They probably thought there was no outside the earth either at some point in human history but they weren't right about that either.

 

[silverpig]

Originally posted by: element

Originally posted by: cquark

Originally posted by: Joerg
Ok i understand that time for this universe begins after the bigbang and there for from our universes perspective there is no before the big bang becuase that is the point of orgin for time and space. But what i cant understand is any scientific explanation of why there can be no before big bang from any perspective.

Your reasoning still sounds like it's based on the idea that spacetime is something separate from the universe, so you could just change your coordinate system or move outside of the universe to observe its formation. The problem is that there is no outside.

Well not as far as you know. They probably thought there was no outside the earth either at some point in human history but they weren't right about that either.

Well what you can say is there's no outside our universe in our universe

 

[Zap Brannigan]

Gravity is weak. It is created by the displacement of space caused from massive bodies such as planets and stars.

Electro Magnetism or EM is much more of a force than G.

Both are key in understanding the universe around us.

 

[natenut]

If anyone is really interested in getting a farily mathamaticly probable answer to the questions raised here read Brian Greene's "The Elegant Universe" Its a PBS Nova special but the book is fairly easy to read. It should have everyone here scratching their heads thinking about Kalabi Yau manifolds and the like. It also has a great section on Einstiens theorys which answers the relationship between speed and time someone had brought up earlyer.



ps. i know that my spelling sucks.


the book!

 

[Zap Brannigan]

Nova is one of the best programs on TV!

 

[Kalessian]

"Well what you can say is there's no outside our universe in our universe"

Can there be an outside our Universe period, though?

I understand that in the CONTEXT of our universe, "before the BB" is invalid, but how could there have been nothing, not a single law or reference point anywhere "out there" (BEYOND our universe). Of course, since I am limited to this universe's point of reference, I could not begin to fathom any type of "existance" without time or space, and I recognize that it would be impossible to prove that another point of refence existed as long as we are still in ours, but I mean, someTHING, at the very least a single law or a rule and therefore a point of reference, had to have been there for that first singularity to have spawned. Logically, is there anyway to DISprove that another reference point could be right outside our own?

On a tangent: Couldn't a "previous" collapsing into a singularity bring with it that single preservable law or whatnot to create a new spacetime again when that singularity re-expands, even if everything has "zero'ed out?" I mean, even zero is something at least, it might not be able to preserve any information, but it would preserve an implication of some sort of law, unlike "invalid."

I'm 18 and stupid.

 

[AluminumStudios]

I'm in the process of watching a VERY fascinating NOVA show on string theory and it talks about gravity a lot in the beginning.

You can actually watch the entire 3 hr show on-line here: http://www.pbs.org/wgbh/nova/elegant/program.html

The first few parts might shed some light on your questions.

 

[r00tcause]

Originally posted by: Joerg
I have to agree with jb i really just dont see how science can justify saying that there is no pre big bang. I mean i understand that it could be the beginning of everything we know such as the properites of matter and stuff specific to this universe but i dont think that this universe is the one and only and i wouldnt doubt that before the end of our life times we will see evidence that the universe will one day shrink in upon itself and again collapse.

Science DOESN'T know nor try to justify in any way that there was not a universe before ours. Anyone who tells you otherwise is wrong. Science has no way, nor will it ever, of answering that question. Its a theory many have thought of, and it is plausible.

 

[r00tcause]

Originally posted by: Joerg
Ok i understand that time for this universe begins after the bigbang and there for from our universes perspective there is no before the big bang becuase that is the point of orgin for time and space. But what i cant understand is any scientific explanation of why there can be no before big bang from any perspective. That seems to lead us to a dead end at sort of the point saying god created the heavens and the earth type of thing.

Yes, yes it does. All scientific explanations lead is down the exact same road is religion. Even if there WAS a universe before ours that contracted and ours is the second, third, or billionth expansion of it, at some point htere still had to either be a 1st, or the universe existed forever. Either way, you are now talking religion here. Note the similarities.

Religion:
God has always existed - how can something always have existed?
Science:
The universe has always existed 0 wait, that didnt make sense earlier, why accept it now?
Religion:
God created the universe - ok but where did God come from? Hmm, doesn't seem to make sense?
Science:
The big bang was the creation of the universe - wait, but then where did the material originate from? A universe cant expand unless something exists TO expand. Cosmic gases dont just appear - damn, this makes no more since than Religion.

Fact:
The universe is not giving up its secrets. Its impossible to ever determine the origin of the universe and EITHR of the 2 explanations lead you to the *exact same logic flaws*.

I know that im going to keep getting the same ansewer if i continue to question about post big bang so i guess i will just leave it where it is now. The new question is if the big bang stretched space and time then couldnt one of the other be some how inversely stretched in effect making the distance or the time between 2 points much smaller enabling a speed greater than light?

Yes, its called warp drive. Welcome to Star Trek.

 

[r00tcause]

Shrinking the space between two points wouldn't increase your speed, but it woul decrease the distance between the two points for anyone travelling between them. In theory, such a warp drive is possible, and papers have been written on it, but we can't produce objects with sufficient density to create such a device. You'd need at least nuclear densities on a large scale and the problem is that nuclei are unstable due to the short range of the strong force; that's why elements after 100 or so last milliseconds at best, and we'd need to construct something containing 10^20 plus nuclei.

Just a little heavy ununpentium (Element 115) should do the trick.

 

[r00tcause]

Originally posted by: Joerg
Ok from my understanding of gravity it is alot like a dent in space and the matter sort of slides into these dents created by great masses of matter. But that still doesnt help me much. I would like a better ansewer as to what is gravity like what causes it? An energy? If so how fast does it react? The speed of light or faster or even instant? And the next questions is if gravity is like dents in space then wouldnt galaxys fall towards each other instead of the doppler effect causing them to pull away from each other?

Super easy question!

Nobody knows. Thats right, we *cant explain gravity at all*. Some people think its a collection of particles (gravitons), some people think its a field effect, like magnetism, some people think its both. Some people think its microscopic midgets pulling on everything.

Science isnt sure. As soon as we figure it out, we'll start manipulating it, like we did with magnetism, and we will all have flying cars.

 

[silverpig]

Originally posted by: r00tcause

Originally posted by: Joerg
Ok from my understanding of gravity it is alot like a dent in space and the matter sort of slides into these dents created by great masses of matter. But that still doesnt help me much. I would like a better ansewer as to what is gravity like what causes it? An energy? If so how fast does it react? The speed of light or faster or even instant? And the next questions is if gravity is like dents in space then wouldnt galaxys fall towards each other instead of the doppler effect causing them to pull away from each other?

Super easy question!

Nobody knows. Thats right, we *cant explain gravity at all*. Some people think its a collection of particles (gravitons), some people think its a field effect, like magnetism, some people think its both. Some people think its microscopic midgets pulling on everything.

Science isnt sure. As soon as we figure it out, we'll start manipulating it, like we did with magnetism, and we will all have flying cars.

Uh, not quite. We can explain gravity very well. General Relativity explains it pretty much perfectly. It's not a quantum theory of gravity, but GR works to explain precession of orbits, frame dragging etc etc.

 

[r00tcause]

Originally posted by: silverpig

Originally posted by: r00tcause

Originally posted by: Joerg
Ok from my understanding of gravity it is alot like a dent in space and the matter sort of slides into these dents created by great masses of matter. But that still doesnt help me much. I would like a better ansewer as to what is gravity like what causes it? An energy? If so how fast does it react? The speed of light or faster or even instant? And the next questions is if gravity is like dents in space then wouldnt galaxys fall towards each other instead of the doppler effect causing them to pull away from each other?

Super easy question!

Nobody knows. Thats right, we *cant explain gravity at all*. Some people think its a collection of particles (gravitons), some people think its a field effect, like magnetism, some people think its both. Some people think its microscopic midgets pulling on everything.

Science isnt sure. As soon as we figure it out, we'll start manipulating it, like we did with magnetism, and we will all have flying cars.

Uh, not quite. We can explain gravity very well. General Relativity explains it pretty much perfectly. It's not a quantum theory of gravity, but GR works to explain precession of orbits, frame dragging etc etc.

You arew the second person I have to explain this to.

You are explaining the PROPERTIES of gravity from observation, not the REASON for gravity. There is a HUGE difference. We do not know what causes gravity or precisely what it is.All we know is how it interacts with the universe. From this we can make accurate calculations.

Example:
What we know about Gravity:
Gravity warps space-time. It increases with mass.

Neither of those explain whether it is a particle, wave, field or exactly what is CAUSING the warp in space-time. We named it gravity, but we dont know what gravity "is".

 

[ahurtt]

At that point, what would we need the cars for?

 

[r00tcause]

Originally posted by: ahurtt
At that point, what would we need the cars for?

Its cold in space.

 

[InseName]

it doesn't react, its just there it'll always be there, and gravity is just a force between all masses that pulls everything towards everything else, the only reason the big band exsists is due to gravity, eventually our universe will pull itself together again and once again form one ball and explode again, in this way no energy is ever lost, it just continually changes form

 

[natenut]

r00tcause!!! good points! you have the eloquence in expalining what i wished i had the patience and communication ablility to do. Like the NOVA special on string theory states, we indeed only can describe the properties of gravity, and then only on the macro scale. that is what the theory of sting theory trys to explain further, Einstiens failed attempts to come up with a unified field theory. These are exciting times in physics!!!