Please help me understand the expansion of space

I think it's reasonable to assume that it expands every where at a very high speed. But if that is the case, how come we don't see the sun and planets in our solar system moving away from us? Even if gravity keeps everything together, shouldn't we be able to measure the slight increase in distances resulted from the expansion?

 

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On the scale of the solar system it is extremely slow I believe.

The sun and planets are gravitationally bound strongly enough that they hold themselves together. I imagine with springs. Say the earth was bound to the sun by a giant spring. The expansion of space would add a tiny extra force pulling outwards on the earth, but that would just make the spring extend a tiny bit, not rip it apart. The acceleration of the expansion of the universe is at a constant rate, so this it equivalent to a constant force being applied to the 'spring', so it doesn't get stronger with time, even though the actual velocity between points initially stationary relative to each other (but not bound in any way) increases.

At least this is the conclusion I have come up with. I struggled with this a little while back but nobody near my office studies cosmology and I didn't find much helpful stuff on the internet, and I was too lazy to search through cosmology books, so I ended up trying to figure it out myself. If I am wrong I would love to hear about it

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i think u'r right.
http://www.thenakedscientists.com/HTML/content/latest-questions/question/2727/

 

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I think it is actually expanding at an increasing rate
http://en.wikipedia.org/wiki/Accelerating_universe
I know wikipedia isnt ideal but I remember reading an article before talking about this accelerated expansion and wikipedia backs me up I think (and so does the link in the previous post), I rememember that it was considered odd as one would have thought that an expanding universe would be larger and thus have greater gravitational pull, thus slowing the rate of expansion but it infact appears the opposite, I could be mistaken???? it easy to misinterpret these kind of things

it seems your own link provides a good answer
I imagine any changes would be so slow that we would find it hard to detect such changes in the lifetime of the entire human species, altough I imagine there are a whole array of means of calculating such things despite the obvious temporal scales and challenges. Look at the rate of lunar drift, hundreds of millions of years ago the moon was so close to the earth it created tides that swept over continents, but it took a long time and gradual decline to get to where it is now, yet I believe they have made calculations on its yearly drift from earth using laser tech, but the distance is tiny, it moves 3.8cm a year further away from earth I read somewhere

 

it's generally believed that all of matter/energy was created during the first moments of the Big Bang so the sum of gravitational pull now should be the same as 13 billion years ago. no one knows why inflation happened or why accelerated expansion continued. most people blame this on dark energy which no one knows what it is. some says it's due to vacuum energy.

Hawking and some other scientists claim that gravity is negative energy while dark energy is positive energy and together they cancel each other out, giving a net energy of 0 in the universe. This supports the theory of
"a universe from nothing, created by quantum fluctuations at t = 0," hence one of the reasons why God is not needed, etc.

 

Yes this is why I said the acceleration of the expansion is constant, not the rate of expansion is constant. It is imprecise languange I admit. I am basing this on the idea that dark energy is what drives that acceleration, and the amount of dark energy in a volume of space is proportional to that volume. Thus, if the galaxy holds itself together in a constant volume of space, even though new space in constantly being created inside it (In my head I picture the new space kind of flowing outwards in all directions from the galaxy), then the amount of dark energy in the volume of the galaxy also remains constant; thus the forces acting to pull the galaxy apart also remain constant.

 

I would just like to say that I am in love with the name of this thread! I think it would be a great character quote...

 

the universe is not expanding on a stellar level, it is expanding on a galactic level. on the stellar level and even the small galactic level gravity is more powerful than the expanding force.

so solar systems stay together even when their component galaxies are moving apart (or together)

the sad thing is that this means that eventually all we will be able to see is one huge galaxy in an ocean of nothingness.

DM

 

If it is a slow expansion then that rules out any sort of Eruption like super blast that thrust outward like an explosion. because we all know objects dont slow down once proppelled in space they keep the momentum.

So if it is indeed moving and expanding at a slow pace then surely it was not a "bang" of sorts it is more like a slowly pulsating, radiating, energy emmitence.


Peace.

 

objects do not slow down unless acted upon by an outside force.

"but there is no outside force in space!" sorry there is gravity. think about it if everything kept moving after the big bang then we would have no solar system or galaxy, just a bunch of dust racing apart from each other.

DM

 

Question though: IIRC didn't some energy get pumped into the universe during inflation? And is the expansion we see related, ie. Is this another phase of inflation which could at some time much much later have a similar effect, of pumping more energy (and therefore more mass) into the universe?

 

as far as i know all of the energy and matter in the universe was created at the instant of the big ban and there has been no more creation since then. doing so would result in the violation of the 2nd law of thermodyamics

DM

 

Purely hypothetical:

lets say that for some reason the universe began expanding at a constant rate and for some unknown reason never moved. As to itself their is know such thing as change as it is already moving so quickly. Lets also say that some great blathering idiot decided to put an equation that only better represented a known term in an easier to understand language. Not saying the idea was easy to understand then, but that enough time has passed and we were possibly able to update the functions of the universe by using something that does not really change from any number.

\(\zeta_{\bigl(s\bigr)} = \sum_{v=1}^{v=\infty} \alpha_{v} sin \bigl( 2\pi v \frac{T}{t} + \alpha_{v}\bigr)\)

Then replace Alpha to represent itself only when there is an error.

\(\zeta_{\bigl(s\bigr)} = \sum_{v=1}^{v=\infty} \alpha_{v} sin \bigl( 2\pi v \frac{T}{t} + 1-erf \frac{n}{\sqrt{2}}\bigr)\)

finally formulate the error to show only the difference in deviation from an equation for the convergence of the circumference from Isaac Newton's arcsin series.

\(\zeta_{\bigl(s\bigr)} = \sum_{v=1}^{v=\infty} \alpha_{v} sin \Biggl( 2\pi v \frac{T}{t} + 1-\frac{\bigl( 2n-1 \bigr)^2}{8n \bigl( 2n+1 \bigr)} \Biggr)\)
Where n=quanta of light.

We should stop getting errors completely after a certain amount of change in time, but any slight deviations in the transformation of light will inevitably become calculable in this manner, unless I am doing something really wrong in my math.

 

wha?

none of you statements in this paragraph seem to make sense

sorry

DM

 

as far as i know all of the energy and matter in the universe was created at the instant of the big ban



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If energy and matter were created at the big bang , I can see matter converted from energy, but then from were comes the energy

 

the energy would be the bang you speak of

DM

 

It never started or stopped expanding, but it "moves" at the infinite and infamous light speed.

 

sorry try again

light speed is not infinite, neither is the expansion of the universe

the expansion of the universe is far bellow light speed, this is proved by the fact that we can see the universe

DM

 

silly boy thinks he knows the universe better than NASA. http://blackholes.stardate.org/resources/articles/article.php?p=birth-of-black-holes

"In other words, at a specific ratio of black-hole mass to galaxy mass, the black hole effectively stops both the galaxy and itself from getting any larger. This remarkable process happens when that ratio is 0.15 percent."

I would just have said it holds the ratio which is "almost" insignificant. So we have a really large number for something small and a very small number for something large. Magically interconnected to all other forms of matter through a process known as quantum entanglement.

 

so now all's we have to ask ourselves is... can we do math's

let's place .15 into the above equation for N and solve and try to find a ratio some small minded individuals may already know about. No, I am not doing the calculations for you.