liciousgre.blogg.se - What is the dark energy

Owing to dark energy, distant galaxies are already speeding up in their apparent recession speed from us. Note that when dark energy reaches a number near 100% in the future, the energy density of the Universe (and, therefore, the expansion rate) will remain constant arbitrarily far ahead in time. The relative importance of different energy components in the Universe at various times in the past. Put these three pieces of knowledge together, and one of the lessons we can derive from them is what the ultimate fate of the Universe will be. Recent measurements (in the last ~30 years) of distant supernovae and the large-scale structure of the Universe have enabled us to make this measurement to outstanding precision as of 2023.

And you must be able to measure how the expansion rate has changed and evolved over time, or in other words, how the Universe was expanding at various points over its cosmic history.

Although two different methods yield results that differ by about ~9% from one another, this difference, as well as the uncertainty we have about the “true value,” is still relatively small.

You must be able to measure how quickly the Universe is expanding today: the expansion rate as we perceive it to be right at this moment in time.

You must know the laws that govern the Universe on the largest scales: in this case, General Relativity, our theory of gravity, is presumed to work extraordinarily well, having passed every cosmic test thrown its way.

Here’s why that difference is so important. Nothing is disappearing from view, although things are disappearing from our reach. We colloquially call this “the disappearing Universe,” but that’s simply a myth. But larger-scale objects will be driven apart by the expanding Universe, receding from one another at ever-increasing speeds. Objects that are gravitationally bound together, like planets, stars, stellar systems, galaxies, and galaxy clusters, will remain so. Owing to the presence of dark energy - the most dominant but least understood component of the Universe - we now know what’s in store for us in the far future.

We emerged from an early, hot, dense state we gravitated and cooled now the Universe is cold, low in matter density, and we have seen what our ultimate fate will be.

The Universe is made not just of atoms, neutrinos, and photons, but also of two mysterious substances: dark matter and dark energy. What is it made of? How is it structured? Where did it come from? How did it get to be the way it is today? And what will be its ultimate fate? After millennia of wondering and philosophizing, the past ~200 years of scientific investigation have finally brought the answers to us.

Since the dawn of humanity, we’ve wondered just what our Universe is.