Watsisname wrote:Mr. Missed Her wrote:Source of the post Since we're talking about dark energy, I've got to ask: What if we're just in a less dense region of space bigger than the observable universe? The more dense universe around our patch would be pulling everything away from our observable region, and it looks like the universe is expanding.A-L-E-X wrote:Source of the post Dark flow, which is what you were alluding to, is something that could be accounted for something outside our observable universe pulling the universe outward (perhaps another universe?
Counter-intuitively this would have zero effect on our volume of space. This is because the gravitational field everywhere inside a hollow sphere, or spherical shell, is equal to zero. The only way to get a uniform accelerating expansion of the observable volume is for the volume to be uniformly filled with something that has this property of dark energy.JackDole wrote:Source of the post I was actually of the opinion that vacuum energy and dark energy are not quite the same.
Yeah, they're not quite the same, but share similar features as an energy density associated with the vacuum. So there is this tantalizing idea that they should be related, but applying concepts of quantum field theory directly to try to predict dark energy's magnitude leads to the infamously wrong prediction by orders of magnitude.
That makes sense because space is nearly a vacuum. Do we have any idea what dark flow is- is it just another property of dark energy? Also, the tantalizing piece that links vacuum energy and dark energy together is Einstein's (in)famous cosmological constant. It's unusual value has some thinking that it hints at an oscillating universe that runs down a bit more with each cycle (and thus the value of the CC gets slightly lower with each iteration.)
Is that new discovery the asteroid that missed earth by just 25,000 miles (one tenth the distance to the moon!) That sure was a narrow escape and we just discovered it!