Va ra kant poet Patch#
Va ra kant poet full#

Assuming the patch expands adiabatically, one may equate this negative work to the increase of mass/energy of the patch. the patch does negative work on its surroundings, because it has negative pressure.

In other words, you're pulling in the opposite direction as the expansion, and so you're doing negative work! ( Update: So why, then, does the expansion speed up? Sure, dark energy's positive energy density means that it's gravitationally attractive to any matter in the Universe, but the magnitude of its negative pressure is what determines the overall rate of expansion!) And so if you're asking where the energy for this 'dark energy' comes from, it comes from the negative work done on the expansion of the Universe!Ī little more technically, as Carroll, Press, and Turner stated in 1992, Image credit: Eugenio Bianchi, Carlo Rovelli & Rocky Kolb. And the third case - a low density Universe - continues to expand forever, as the gravitational attraction between all the Universe's matter and radiation finds itself unable to counteract the initial expansion.

The second image is one with a large initial expansion, but the amount of matter and energy is just one subatomic particle short of being able to recollapse the Universe! In this critical case, the Universe's expansion rate continues to slow, asymptoting towards zero, but never reverses. Looking at the image above, the leftmost diagram represents an expanding Universe where gravity eventually wins: the initial expansion is not enough for the amount of matter-and-energy present, and the Universe eventually reverses its expansion, recollapsing in a Big Crunch. So - in the simplest terms you can imagine - that's what you've got: an initially, rapidly expanding Universe, where gravity tries to slow, reverse, and recollapse it.

Va ra kant poet full#

But you also know that if your Universe is full of matter and energy, the force of gravity is going to do everything it can to try and pull this expanding Universe back together again. You can imagine the Early Universe - at least the portion of it observable to us - as a hot, dense, rapidly expanding sphere of matter and energy. Image credit: Adam Reiss,, retrieved from.