Planck Length .. and a 7yr old
Discussion
skeeterm5 said:
If an atom was expanded to the size of the known universe, the Planck length would scarcely reach the height of an average tree.
I think a 7 year old could get that.
S
How does a 7 year old comprehend the size of the universe though? I certainly can't and I've looked at the numbers but in terms of truly comprehending the size difference between a solar system, galaxy and universe is terribly difficult.I think a 7 year old could get that.
S
Unless we're limiting comprehension to big, huge and huger!
Its fascinating stuff, well done on the teaspoon / pacific thingamibob.
I love the idea that when you drop a solid object, like say a board rubber onto a desk, gravity takes a split second to "force" it onto the desk, yet the electromagnetic forces between the atoms of the desk and the atoms of the board rubber act on each other instantaneously to stop the rubber as it hits the desk.
also when I first read about neutrinos - things so small they can pass right through the earth and including living things without being noticed...I was like WTF? eg sunlight has elements that we can "see" and not "see" yet we know they're there...
I need a lie down
I love the idea that when you drop a solid object, like say a board rubber onto a desk, gravity takes a split second to "force" it onto the desk, yet the electromagnetic forces between the atoms of the desk and the atoms of the board rubber act on each other instantaneously to stop the rubber as it hits the desk.
also when I first read about neutrinos - things so small they can pass right through the earth and including living things without being noticed...I was like WTF? eg sunlight has elements that we can "see" and not "see" yet we know they're there...
I need a lie down
jimmy156 said:
There are all sorts of things dissolved in sea water, including gold! I seem to remember that the germans, in trying to repay their debt after one of the world wars, tried to collect some of this gold, but it was costing them significantly more to find it then the gold was worth!
I recall when Kevin Keegan signed Alan Shearer for Newcasle for £15M he said it was a bargian, and that Shearer was worth his weight in gold. So I looked up Shearer's weight, and on the gold price per ounce at the time, Shearer's weight in gold was worth just over £1MSo by his own admission, Keegan paid about £14M too much!!!
Nom de ploom said:
I love the idea that when you drop a solid object, like say a board rubber onto a desk, gravity takes a split second to "force" it onto the desk, yet the electromagnetic forces between the atoms of the desk and the atoms of the board rubber act on each other instantaneously to stop the rubber as it hits the desk.
Not following you with that one. Fascinating stuff though.
I think what I was trying to explain, poorly, was that gravity is a weak force compared to the repulsive electromagnetic forces of atoms.
gravity brings the object down onto the table in a measureble amount of time, albeit short, but the forces at work within the atoms work in an instant.
gravity brings the object down onto the table in a measureble amount of time, albeit short, but the forces at work within the atoms work in an instant.
jimmy156 said:
Slink said:
TwigtheWonderkid said:
There are approx the same number of atoms in a teaspoon of water as there are teaspoons of water in the pacific ocean.
I haven't done the maths to verify these!!!
I might be incorrect here, but i think you are wrong.I haven't done the maths to verify these!!!
tap water does not contain much apart from a bit of fluoride and other bits like other minerals.
whereas sea water has a hell of a lot of salt dissolved in it, so would be more dense i think (not a lot i grant you, but a bit)
so the salt water will have more atoms in than tap water as there is not just water, but water AND salt.
anyway, a teaspoon of water (5 grams) would have 5/18's of a mole of water molecules. This is 1.67x10-23 molecules of water (167,000,000,000,000,000,000,000) Each molecule of water has three atoms so 5.01x10-23 atoms in a teaspoon of water.
From various sources, the pacific ocean contains 51% of the worlds oceanic water, and the mass of the worlds oceans to be about 1.4x10-21 kg. so 51% of that is 7.14x10-20 kg, which would be 7.14x10-23 grammes, 5 grammes per teaspoon = 1.43x10-23 teaspoons
So by that calculation (the numbers for the second half could be very wrong!) there are 3.5 times as many atoms (and about the same number of water molecules!) in a teaspoon of water as there are teaspoons of water in the pacific.
There are all sorts of things dissolved in sea water, including gold! I seem to remember that the germans, in trying to repay their debt after one of the world wars, tried to collect some of this gold, but it was costing them significantly more to find it then the gold was worth!
ETA: this took a few edits, its late
Edited by jimmy156 on Tuesday 2nd July 23:45
im guessing there will be the same amount of water atoms, but there will be more atoms in the teaspoon because of the stuff dissolved into the sea water.
IainT said:
How does a 7 year old comprehend the size of the universe though? I certainly can't and I've looked at the numbers but in terms of truly comprehending the size difference between a solar system, galaxy and universe is terribly difficult.
Unless we're limiting comprehension to big, huge and huger!
Take said 7 year old into the garden at night, look at the sky, say look how big that is, now look at tree and make the comparison.Unless we're limiting comprehension to big, huge and huger!
I think that is probably good enough.....
S
skeeterm5 said:
IainT said:
How does a 7 year old comprehend the size of the universe though? I certainly can't and I've looked at the numbers but in terms of truly comprehending the size difference between a solar system, galaxy and universe is terribly difficult.
Unless we're limiting comprehension to big, huge and huger!
Take said 7 year old into the garden at night, look at the sky, say look how big that is, now look at tree and make the comparison.Unless we're limiting comprehension to big, huge and huger!
I think that is probably good enough.....
S
jimmy156 said:
Slink said:
yes, but there will be more atoms in the teaspoon from the sea, than from your tap, as there is lots more things dissolved into it.
True, it will be more dense, but yo're completely missing the point of the analogy. It has nothing to do with the relative densities of sea water and tap water. im guessing there will be the same amount of water atoms, but there will be more atoms in the teaspoon because of the stuff dissolved into the sea water.
Each atom of dissolved material in the teaspoon will displace either another atom of material or a single atom of water from the teaspoon?
there must be some complicated maths to figure this bit out
SystemParanoia said:
but surely by that logic there wont be the the same amount of water atoms.. as the teaspoon holds a fixed volume
Each atom of dissolved material in the teaspoon will displace either another atom of material or a single atom of water from the teaspoon?
there must be some complicated maths to figure this bit out
This is incorrect, due to the way the molecules of water arrange themselves around a solute. For example if you dissolve Sodium Chloride (salt) in water to make a saturated solution, there will actually be a reduction in the volume of the water, i.e more water molecules on your teaspoon. This still isn't relavent to the original anaology though! There are the same number of water molecules in 1 teaspoon of water as there are teaspoons of water in the pacific ocean It doesent say anything about salt water vs fresh water, or which type of water is to be used in the teaspoon.Each atom of dissolved material in the teaspoon will displace either another atom of material or a single atom of water from the teaspoon?
there must be some complicated maths to figure this bit out
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