Dark Energy idea/question

[ignorant]

I was thinking about dark energy the other day and I had a thought. I wondered, could it be possible that we are near the edge of the universe figuratively speaking and the force that makes it appear that we are actually speeding up on our path outward could in fact be the large amount of mass that was blown away initially when the big bang occured.

It would make sense that the first galaxies that formed would have been the farthest out and the most massive. If that were the case and they burned out rather quickly (IIRC the average lifespan of a super massive star is around 2 million years) by this point in the age of the universe almost if not all the stars from those primordial galaxies would have burned up and would appear to be completely blank. The gravitational pull from these massive galaxies would still be there and could be pulling on the Milky Way causing us to actually go faster than than what the models predict we should be.

Clearly I'm no astronomer nor am I a physicist, so I was wondering if there was any literature around that had already disproved such an idea, or possibly even attempt to prove it. If not could it even be possible?

 

[ramparts]

The problem is that you're talking about the Universe in terms different from how scientists see it these days. It doesn't really make sense to talk about us being near the "edge" of the Universe, with the center being where the Big Bang happened, because the Big Bang happened everywhere. It was an expansion of space itself, rather than an expansion within space, if that makes sense. I know it's a weird idea, but some pondering will get you there Think about the Universe as being on the surface of a balloon (if the Universe were two-dimensional). If you blow up that balloon, then it expands, even though there's no center to the surface (or the Universe). All the points on the balloon - galaxies, if you will - will get farther away from each other without ever moving, because the background itself - the balloon - is expanding.

Another thought about us being near the edge of the Universe - that seems to contradict the observations that the expansion of the Universe is the same in all directions. In fact, if you didn't want to think about the Big Bang as being an expansion of space, then the fact that we see the same expansion in every direction would suggest we're in the very center of the Universe, not on the edge, an idea that also has a ton of flaws!

Hope that helps. Let me know if you still have any questions (I'm sure you will!).

 

[yevaud]

Yeah, no edge: a "No Boundary Condition."

 

[ignorant]

You are absolutely right, that does open up more questions. (please don't take my questions as me thinking you are wrong, I firmly believe you know more on this subject than myself, the questions are just to fill the gaps in my own knowledge a little bit)

Firstly, is it possible that our observations are such that our observable area is just a small quadrant of the known universe, as in the time of the big bang could have occured much longer ago than the current models predict. Such that the light we see from the distant past galaxies are as far back as we can currently see, and when we have more powerful forms of telescopes we will be able to see farther into the past.

Second, do you know of a good spot to go read up on the current view of the big bang, as my view (as I was taught in college years and years ago) is that all the matter in the universe was condensed into a singularity of nearly infinite mass and a force, possibly space itself condensed around the singulariy, caused the explosion of the mass in all directions. Ofcourse this idea was also in the same time frame when the belief that the universe would eventually contract back in on itself due to gravity and start the whole process over again.

Finally, based on what you have said, it would appear that the current belief is that there isn't dark energy at all, rather its the expansion of the universe that is causing things to accelerate away from each other. Wouldn't this be at odds with the belief that space itself is infinite and imply that there is in fact an edge to space. Also would that not imply that there would be a limit to the amount of area that space itself can reach. It would seem that the amount of energy released at the big bang would have to be a finite number and as such its energy release would be enough to force the universe to expand only so far. Using the balloon analogy that you were kind enough to help me with earlier, the amount of energy used to add air to the balloon would be proportional to the amount of size the balloon could reach saying it doesn't pop first.

Again, I'm not trying to poke holes in your answers that you have provided me with, rather, I am simply trying to get answers to my questions from yall that are smarter than I on the subject.

Thanks for the answers so far and I am looking forward to a bit more help.

 

[ramparts]

The expansion of the universe is purely determined by gravity. So yeah, the initial "bang" will only do so much, after which the matter and radiation in the universe will cause the expansion to slow. That should be pretty intuitive: gravity pulls stuff together, so it should slow the expansion down. So dark energy is the name we give to whatever stuff (if it is stuff) is causing the expansion to speed up, more than the matter in the universe is causing it to slow down. If it is energy, it has to be very exotic, since it would essentially have an "antigravitational" effect, but it is physically possible.

I would recommend browsing through Wikipedia, maybe starting here:

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

and working your way around interesting-looking articles. I'd also recommend this article for the concept of space itself expanding:

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

since some of your questions still seem to assume that the Big Bang was an explosion in the conventional sense. Don't think of it as an explosion of matter, think of it as an expansion of space, so that the stuff inside the universe isn't even moving. Just like blowing up a balloon really quickly.

 

[ignorant]

Hmm, so wikipedia is now a viable source? I was working under the impression that wikipedia is a good source for random stuff, but in depth stuff like this was a bit of a no no to look at on there. Regardless I'll give it a look. Thanks for the info again.

 

[ramparts]

I actually quite like Wikipedia for this stuff. Even accomplished researchers (or students, like myself) will sometimes look things up on Wiki for research projects - though of course you double-check it in a book or paper and cite that when it comes time to make things formal. In my experience information in the science articles is rarely wrong, and in fact it has a combination of decent mathematical depth for experts (in some articles) and very good explanations for laymen in a lot of articles, like the ones I linked to. Obviously it's not the most reliable source but almost all of the time it's perfectly "reliable enough." The editor base is large enough that major errors just don't propagate very long.

 

[ignorant]

ah good to know, obviously I never got the opportunity to write an article for class using wiki, ah i guess im officially getting old...

 

[nimbus]

Wikipedia articles are as good as their sources.

 

[MeteorWayne]

Wiki articles can be good or bad. If someone who understands the subject reads it and tells you it's a good summary of our current understanding, you can trust that as much as you trust the poster himself.