The Universe is just not the same right now because it was yesterday. With every second that goes by, a lot of refined however essential adjustments happen, even when a lot of them are imperceptible on measurable, human timescales. The Universe is increasing, which implies that the distances between the most important cosmic constructions are rising with time.
A second in the past, the Universe was barely smaller; a second from now, the Universe might be barely bigger. However, these delicate adjustments each construct up over giant, cosmic timescales, and have an effect on extra than simply distances. Because the Universe expands, the relative significance of radiation, matter, neutrinos, and dark vitality all change. The temperature of the Universe adjustments. And what you’d see within the sky would change dramatically as nicely. All advised, there are six completely different eras we will break the Universe into, and we’re already within the ultimate one.
A Universe that has been around longer, subsequently, can have expanded extra. It is going to be cooler sooner or later and was hotter prior to now; it was gravitationally extra uniform prior to now and is clumpier now; it was smaller prior to now and will probably be a lot, a lot bigger sooner or later.
By making use of the legal guidelines of physics to the Universe, and evaluating the attainable options with the observations and measurements we have obtained, we will decide each the place we got here from and the place we’re headed. We are able to extrapolate our previous historical past all the best way again to the start of the recent Big Bang and even earlier than, to a period of cosmic inflation. We are able to extrapolate our present Universe into the far distant future as properly and foresee the ultimate fate that awaits all the things that exist.
This last era, of dark energy domination, has already begun. Dark energy grew to become necessary for the Universe’s enlargement 6 billion years in the past and commenced dominating the Universe’s vitality content material across the time our Sun and Solar System have been being born. The Universe might have six distinctive levels; however, for everything of Earth’s history, we have already been within the closing one.