Bad Astronomy | Astronomers think the universe is 31.5%


If you want to understand the universe – and we do – you have to understand what is in it. I don’t mean stars and planets and black holes and the like. We need to be more comprehensive.

How much energy is there in the universe? How much is it? And to be a little more specific, what kind of energy and matter?

We call it Universe mass / energy budget. Like a household budget, it (hopefully) accounts for everything in it, divided by type. In the case of the universe, we know that it is made in decreasing order – dark energy, dark matter and ordinary matter. But how much of each?

A new study looked just the case, and came up with a fairly narrow number: 31.5% is made up of 1.3% cosmic matter (which, in turn, is 68.5% dark energy).

These numbers are very important. If there was less matter in the universe, it would expand more rapidly – in a sense, the gravity of that case slows down the expansion.

It also has implications for stuff In The universe, and not just the universe. For example, gravity in the early universe helped palpate matter, because it was attracted to itself. It comes out of the hot soup of the stuff, forming galaxies and galaxies. If the budget were different, galaxies and clusters would have looked different, or not formed at all.

We owe our existence to these numbers.

In fact, it was the galaxy cluster that focused on the new work. These are huge collections of entire galaxies, hundreds or thousands, all held together by their mutual gravity. Their composition depends on the density of matter in the universe, so by examining them scientists can find that density.

He developed a way to find clusters in which to do as objectively as possible. They stared at 700,000 galaxies, then examined their locations and motions in space to see if they belonged to groups. From this sample he selected 756 nearby galaxy clusters (about 1.6 billion light years away, so “near” is relative) to use in his analysis.

They then found what is called a cluster mass function, which is the number of clusters for a universe in a given volume in space for a given cluster. So in some part of the universe you can see a lot of low-mass groups, low-middle-weight, and very few truly true guineas, for example. This distribution is sensitive to the density of matter in the universe, and is complicated by the fact that the density changes over time as the universe expands, as well as the difficulty of determining the mass of a cluster.

That last bit is a tuff. There are a lot of ways to estimate the mass of a cluster, many of which are statistical in nature (looking at too many clusters to average noise statistics). These present other issues, however, making this difficult. In this case, scientists opted to use what is called the viral method to gain mass – as galaxies rotate in a group, they exchange energy (faster than slower ones). Pulls, for example, speeds them up). It depends on the total mass of the cluster, and provides a very good way to obtain that number.

They then ran the numbers to see what kind of temporal mass density they needed to explain the mass distribution of bunches, and using 31.5% In college Their data found them to be 31% with an uncertainty of about 2.3%, but combining their results with other studies yielded a slightly more accurate figure).

In general, this number is one Little This is slightly higher than most other methods (it varies from 25-30% depending on how you measure it), but not dangerously so. They claim that their number is the most accurate measurement so far, but I will let other experts claim it.

It also allows you to calculate the average density of matter in the universe, and it is about 10-23 Grams per cubic meter. She is a teeny This is equivalent to about 6 hydrogen atoms per cubic meter. For comparison, the air at sea level is about 1,200 grams per cubic meter, or about 1025 Atoms per cubic meter – a factor of more than one septillion (or one million million million million). Space is really empty.

I am also noting The total Case, including dark and “normal” case. Material budget on one’s own Universe has about 5 to 1 darkness. This is normal, so about 84/16 is divided. However this ratio is not very well known. One idea, incidentally, is that dark matter is made up of axes, a theoretical particle with very little mass. If so, then that cubic meter would be like 1 hydrogen atom in space and several billions of axes.

so there you go. This new study, should it be completed, is another step to make it all straightforward. Every day we get to know a little, okay, The universe, And why we are here. This may sound a little cryptic, but look around you. All items you have seen are present., And this is because of how the universe works. Looking under its hood is one of the best things humans can do.

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