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Mimi · **Joined:** 27th Mar, 2008 **Posts:** 26097

Hydrogen is the most abundant element in the universe. But the universe is infinite. So there most surely be an infinite amount of hydrogen. And infinite amounts of the other elements, so how is one more abundant than the others?

Trooper · **Joined:** 4th Mar, 2010 **Posts:** 22392

If the universe is infinite, then all possible variants of existence exist, including the possibility that the universe isn't infinite.

Mr Dave · **Posted:** Tue Dec 03, 2019 9:14

Mimi wrote:

Hydrogen is the most abundant element in the universe. But the universe is infinite. So there most surely be an infinite amount of hydrogen. And infinite amounts of the other elements, so how is one more abundant than the others?

The amount of places hydrogen could be is infinite.

And the universe is a currant bun.

myp · **Posted:** Tue Dec 03, 2019 9:18

If the universe is infinite and hydrogen is finite, then the amount of hydrogen in the universe is effectively zero

MaliA · **Posted:** Tue Dec 03, 2019 9:31

God put them there.

Malc · **Posted:** Tue Dec 03, 2019 9:34

Mimi wrote:

Hydrogen is the most abundant element in the universe. But the universe is infinite. So there most surely be an infinite amount of hydrogen. And infinite amounts of the other elements, so how is one more abundant than the others?

Malc · **Posted:** Tue Dec 03, 2019 9:43

Or if you want less whimsy

ApplePieOfDestiny · **Joined:** 17th Dec, 2008 **Posts:** 8293

On the subject of infinity, I saw a tweet thread the other day challenging the Hilbert’s hotel theory.

Specifically, if the hotel is infinite, it by definition takes up the whole universe and so therefore where the fuck does a new guest arrive from to require them all to do the room shuffle?

DavPaz · **Joined:** 27th Jun, 2008 **Posts:** 38660

The universe isn't infinite, it just wraps around at the edges in three dimensions, like a doughnut.

Giphy "donut shaped universe":
https://media2.giphy.com/media/3oKIPdQyoFG3RSSOL6/giphy-loop.mp4

Kern · **Posted:** Tue Dec 03, 2019 10:15

A creator and a multiverse. Well done Giphy.

Pundabaya · **Joined:** 30th Mar, 2008 **Posts:** 5016

No. You could have an infinite hotel, that is in the centre of infinite Swindon*, that sits within an infinite England, that is a part of the infinite UK, that sits on the infinite Earth, which is part of an infinite solar system that is part of the infinite galaxy that is part of the infinite universe. What I'm saying, is that you can have infinities of different 'sizes'. Which kind of makes sense. Like, if you had an infinite universe which contains infinite matter (planets, stars, asteroids etc) but the matter takes the form of solar systems, the total volume of the universe is more than the total volume of the matter, because of the empty space in between. They are both infinite, but the universe is a bigger infinity.

Which answers the original question. If you have an infinite universe containing infinite elements, hydrogen may very well be more abundant than carbon, which is more abundant than gold, while still all being infinite.

*the real Swindon is not infinite. It just feels that way.

Doctor Glyndwr · **Joined:** 30th Mar, 2008 **Posts:** 32624

Mimi wrote:

But the universe is infinite.

The universe may or may not be infinite - we cannot know. But the observable universe is definitely finite. Light travels at a fixed speed [1] and the Big Bang was a fixed amount of time ago. Therefore, there is a maximum distance light can have travelled between the Big Bang and now, and we cannot get any information about anything further away than that. So we can talk about "all the hydrogen in the observable universe" meaningfully.

Quote:

So there most surely be an infinite amount of hydrogen. And infinite amounts of the other elements, so how is one more abundant than the others?

As others have said, some infinities are larger than others. Consider the set of integers (often written as Z): 1, 2, 3, 4, 5, ... There's an infinity of them. Now consider the set of real numbers (often written as R): 1.1, 1.2, 1.25, 1.257, 1.2573, 1.3, 2.0, 2.4... There's an infinity of them, too. But every integer is also a real number, and so R contains Z, and has extra numbers on top. Therefore, the size of R is greater than the size of Z, even though both are infinite.

[1] in a vacuum, anyway

DavPaz · **Joined:** 27th Jun, 2008 **Posts:** 38660

Giphy "fuck yeah science":
https://media2.giphy.com/media/JIrUXT1Av9x2o/giphy-loop.mp4

That real number explanation nailed it for me Doc. Ta!

Warhead · Noob as of 6/8/10

OK! JUST STOP IT, NOW, BEFORE SOMEONE REALISES NONE OF IT IS REAL AND WE ALL WINK OUT OF EXISTENCE, BECAUSE I HAVEN'T HAD LUNCH YET.

Warhead · Noob as of 6/8/10

Mimi wrote:

Hydrogen is the most abundant element in the universe. But the universe is infinite. So there most surely be an infinite amount of hydrogen. And infinite amounts of the other elements, so how is one more abundant than the others?

All the hydrogen has floated away, but don't tell anyone or they'll panic.

Findus Fop · **Joined:** 14th May, 2009 **Posts:** 4357

Doctor Glyndwr wrote:

Mimi wrote:

But the universe is infinite.

The universe may or may not be infinite - we cannot know. But the observable universe is definitely finite. Light travels at a fixed speed [1] and the Big Bang was a fixed amount of time ago. Therefore, there is a maximum distance light can have travelled between the Big Bang and now, and we cannot get any information about anything further away than that. So we can talk about "all the hydrogen in the observable universe" meaningfully.

Quote:

So there most surely be an infinite amount of hydrogen. And infinite amounts of the other elements, so how is one more abundant than the others?

As others have said, some infinities are larger than others. Consider the set of integers (often written as Z): 1, 2, 3, 4, 5, ... There's an infinity of them. Now consider the set of real numbers (often written as R): 1.1, 1.2, 1.25, 1.257, 1.2573, 1.3, 2.0, 2.4... There's an infinity of them, too. But every integer is also a real number, and so R contains Z, and has extra numbers on top. Therefore, the size of R is greater than the size of Z, even though both are infinite.

[1] in a vacuum, anyway

Christ, I actually understood that.

Jem · **Posted:** Wed Dec 04, 2019 10:56

This thread makes my head hurt.

Malc · **Posted:** Wed Dec 04, 2019 11:39

Doctor Glyndwr wrote:

...
the Big Bang was a fixed amount of time ago.
..

There seems to be an increasingly vexing problem here with working out exactly when that was.

Cosmologists use a couple of different methods to work out the age of the universe, and both methods used to have answers whose error bars overlapped. However, that apparently is no longer the case, and now there are 2 distinct ages of the universe depending on which method you use.

It will be interesting to see if this difference leads to new theories and understanding.

Zardoz · **Posted:** Wed Dec 04, 2019 12:32

Jem wrote:

This thread makes my head hurt.

Hardly surprising as this 'Universe' is merely a construct within your dream.

Don't wake up!

Be Excellent To Each Other

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