How many particles in the Universe? - Numberphile
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It's not how many particles there are in a human body at one point in time that counts but how many particles of air, water, food, clothes, toiletries, etc. each one uses in a lifetime to keep alive. If all the particles were in humans where would the air and food, etc be?
It's more worthwhile calculating how many particles there are in the accessible part of the Earth's surface, air and water, how much land is needed per person to produce a lifetime's worth of food and other essentials (and room for rubbish, and thus work out how many people is the maximum number the Earth can support in one go (or indefinitely if the processes are sustainable) to a comfortable standard of living for an average length lifetime. Then take away the proportion of land set aside for other species and keeping the natural balance of the environment. Perhaps humans should use less than 10% of the land area. or is 20% enough? What about forests, wildlife, oceans? I think we must be close to or beyond the maximum limit already so the growth rate ought to decline to zero to maintain a stable population.
I hope when they plan on sending humans to Mars they know how many tons of 'stuff' people consume in the few years the mission is expected to last and allow for extra needs if things go wrong (extra toilet paper for runny noses and so on!
Date: 2022-04-08
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Comments and reviews: 9
SJ
But isn't the constituent proportion of elements within the universe determined by mass? So hydrogen makes up 75% of the mass of -normal- matter in the universe, with the other 25% helium. But since a helium atom is four times as massive as hydrogen atom wouldn't that mean for every 75 hydrogen atoms there would only be 6 or so helium atoms? Which seems to contradict the argument made at 4: 40 that said that for every four hydrogen there would be 1 helium. Or am I just missing something (wouldn't be surprised if I was.
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But isn't the constituent proportion of elements within the universe determined by mass? So hydrogen makes up 75% of the mass of -normal- matter in the universe, with the other 25% helium. But since a helium atom is four times as massive as hydrogen atom wouldn't that mean for every 75 hydrogen atoms there would only be 6 or so helium atoms? Which seems to contradict the argument made at 4: 40 that said that for every four hydrogen there would be 1 helium. Or am I just missing something (wouldn't be surprised if I was.
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Tom
The calculation is out by a factor of 100. With those figures, I made it 86. 04 years! Even so, with the rate r = 1. 11 per year and assuming everybody lives extremely long lives, shouldn't we have:
r-T = pop_all/pop_now, from which (with r = 1. 11 and pop_all/pop_now = 3 x 10-41)
T-ln(1. 11) = ln (3 x 10-41)
giving
T = ln (3 x 10-41) / ln(1. 11?
In which case, brace yourself! It will take a mere 915. 14 years!
But of course, I could be wrong.
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The calculation is out by a factor of 100. With those figures, I made it 86. 04 years! Even so, with the rate r = 1. 11 per year and assuming everybody lives extremely long lives, shouldn't we have:
r-T = pop_all/pop_now, from which (with r = 1. 11 and pop_all/pop_now = 3 x 10-41)
T-ln(1. 11) = ln (3 x 10-41)
giving
T = ln (3 x 10-41) / ln(1. 11?
In which case, brace yourself! It will take a mere 915. 14 years!
But of course, I could be wrong.
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Mary
I just learned something INSANE about powers of ten, and how big numbers get. There are ten to the power of 14 atoms in a cell. Knowing that, you'd think that the numbers of atoms in the universe would be unbelievably huge. HOwever, there are -only- ten to the power of 80 atoms in the whole universe. CRAZY! That's how big the powers of ten get really fast. So just imagine how much bigger ten to the power of 100 is, compared to power of 80.
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I just learned something INSANE about powers of ten, and how big numbers get. There are ten to the power of 14 atoms in a cell. Knowing that, you'd think that the numbers of atoms in the universe would be unbelievably huge. HOwever, there are -only- ten to the power of 80 atoms in the whole universe. CRAZY! That's how big the powers of ten get really fast. So just imagine how much bigger ten to the power of 100 is, compared to power of 80.
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Spitler
-. in so many years. we wouldve used up all the particles in the universe-
thats only if every human is born with completely new atoms, nothing can be reused from previous generations
anyone wants to bother working out what that number would be if you allow for recycling? One has to somehow estimate a lot of stuff i dont know how to
(i know this is the second comment in 10 min)
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-. in so many years. we wouldve used up all the particles in the universe-
thats only if every human is born with completely new atoms, nothing can be reused from previous generations
anyone wants to bother working out what that number would be if you allow for recycling? One has to somehow estimate a lot of stuff i dont know how to
(i know this is the second comment in 10 min)
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Simon
You start by saying that 75% of baryons are in hydrogen and 25% in helium. Then you go on and calculate with 75% of atoms being hydrogen. That's not the same! In a world with 75% hydrogen atoms, only 3/7 baryons are in hydrogen - far less than 75%. And 4/7 are in helium, far more than 25%. Ratios almost flip. I don't know which of the assumptions is correct, but they are not identical.
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You start by saying that 75% of baryons are in hydrogen and 25% in helium. Then you go on and calculate with 75% of atoms being hydrogen. That's not the same! In a world with 75% hydrogen atoms, only 3/7 baryons are in hydrogen - far less than 75%. And 4/7 are in helium, far more than 25%. Ratios almost flip. I don't know which of the assumptions is correct, but they are not identical.
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23jackleeder
Particles are really big and they're spread out and they pop in and out of existence, so trying to totalize them seems a bit ambiguous. I would be interested in knowing how many Planck scale divisions the observable universe could contain. We could start off smaller and work up - so how many Planck scale units does a cubic light year contain?
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Particles are really big and they're spread out and they pop in and out of existence, so trying to totalize them seems a bit ambiguous. I would be interested in knowing how many Planck scale divisions the observable universe could contain. We could start off smaller and work up - so how many Planck scale units does a cubic light year contain?
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Steve
It should be pointed out that he compared 3 H atoms to 1 He, this is incorrect. By -weight- it's 75% H to 25% He but by -number of atoms- as he clearly shows he's calculating, it's 92% H, to about 8% He, lowering the number of particles, because there's 4 particles per atom of He, but only 1 per atom of H.
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It should be pointed out that he compared 3 H atoms to 1 He, this is incorrect. By -weight- it's 75% H to 25% He but by -number of atoms- as he clearly shows he's calculating, it's 92% H, to about 8% He, lowering the number of particles, because there's 4 particles per atom of He, but only 1 per atom of H.
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David
There is a minor error in the calculation. The Universe is 75% hydrogen by mass, not by number of nuclei. This means the 26/7 should have been 31/8 because hydrogen atoms outnumber helium atoms 12 to 1, not 3 to 1. This does not change the answer meaningfully; it is still a huge number.
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There is a minor error in the calculation. The Universe is 75% hydrogen by mass, not by number of nuclei. This means the 26/7 should have been 31/8 because hydrogen atoms outnumber helium atoms 12 to 1, not 3 to 1. This does not change the answer meaningfully; it is still a huge number.
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Clayton
The math seems off. 10 to the 29th increasing at 1% per year. There's still 10 to the 51st particles left. How does the human population increase that much in only 8604 years? 3 million years to hit 10 to the 29th, but only 8000ish years to to hit 10 the the 80th with only 1% growth?
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The math seems off. 10 to the 29th increasing at 1% per year. There's still 10 to the 51st particles left. How does the human population increase that much in only 8604 years? 3 million years to hit 10 to the 29th, but only 8000ish years to to hit 10 the the 80th with only 1% growth?
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