Thread: Science Buffs

Originally Posted by Twisted Tenon

My original thoughts were that the Earth in its pristine state (before humans) maintained a balance with the elements lost to space by creating new gases to replace those lost. While not attempting to introduce Climate Change into the topic, I wonder if humans have caused an imbalance and therefore altered this balance preventing the earth from replacing these gases. Which when you come to think of it supports BobL's argument that the earth is getting lighter.

TT

I have to be careful not to go down the climate change path and incur the wrath of , but the earth's balance is dynamic in that there is constant change. There is still no significant alteration in the earth's weight, but the nature of the change may be different.

I think this is the issue that is so controversial. The products of our existence may inhibit or change the manner in which we live. Very, very few people dispute that the earth is changing, but the controversy revolves around whether mankind can continue to exist under these conditions and how significantly makind is to blame. The fact remains that, in principle, the earth's mass is to all intent and purpose constant.

Small amounts of weight are indeed lost, but not enough to make a difference. I think somebody else pointed out that the sun, too, is losing miroscopic amounts of mass related to it's enormous size.

Regards
Paul

Originally Posted by Bushmiller

Small amounts of weight are indeed lost, but not enough to make a difference. I think somebody else pointed out that the sun, too, is losing miroscopic amounts of mass related to it's enormous size.

The earth loses 0.00000000000000000001% of it's mass every year

The sun loses about 0.000000000001 % of it's mass every year.

In relative terms, the sun is losing mass 10,000,000 times faster than the earth.

Despite this the sun will only lose about 0.1% of its mass during it's whole lifetime.

Another way of putting this is the sun loses the equivalent mass of the earth about every 4 years.

Twisted Tenon,
it's a problem humans have coping with non human sizes, either much bigger or much smaller.

I was going to do the % thing with lots of zeros but I'll do it a different way.
The earth weight changes in the order of 10's of thousands of tons a year according to BobL. And we can all sort of understand that, maybe compare it to 500 or 1000 semi trailer loads. That seems a lot, we can still grasp the size of a large number of semi traillers.
But the earth weighs (in Tonnes) 6 with _21_ zeroes after it. Our brains just can't compare that number with anything in our normal experience.

The earth is so much bigger than the semi trailers (which we know are heavy) that the semis really might as well not be there at all.

The sun (in tonnes) is 2 with _27_ zeroes after it. That is almost a million times heavier than the earth.

And this gets back to the original question...
With all these extra people it seems logical that it should make a difference to the weight of the earth. But fly and BobL are right the extra people come from the resources that are already on earth and we (in fact all the living things on the earth) make up only a tiny amount of the chemicals which the earth contains.

For instance if an average person weighs 70kg and are 70% water (so the story goes!) each person must be equivalent to about 49litres of water. With 7 Billion people in the world that's a total of 343 billion litres of water, which is a lot! (about 3 with 11 zeroes). It's really getting in to that unimaginable realm.
But the oceans contain about (1 with 21 zeroes) litres so people are about 0.0000000003% of the water in the world. (I might have got one zero extra or less here!)
Anyway, we can see 7 billion people and the effect they have and we might think that is big because we can sort of imagine it as say, 1600 Sydneys. But we don't (can't) notice the amount of water that has been taken out of the worlds water cycle to become us humans because the amount of water in the world is so much bigger.

Hope this helps (and doesn't make it worse)!

Regards

Now we need to factor in the fact that 20 years ago we contained 49 cents of chemicals RRP.

Hi Paul
I too don't want to bring Climate Change into this thread as it gets too emotional. My thoughts were that CC may be affecting the Earth's' mass. It is probably a simplistic view.

The way you and swk put it makes sense. All life on earth is simply re using existing water.

TT

Originally Posted by Twisted Tenon

Hi Paul
I too don't want to bring Climate Change into this thread as it gets too emotional. My thoughts were that CC may be affecting the Earth's' mass. It is probably a simplistic view.

Whenever something has more energy like heat it also has more mass. On the scale of a cup of tea this is minuscule but on the scale of the earth it works out to be tons (but of course is still relatively minuscule)

Whether the CC is man made or not doesn't matter, if CC makes the earth hotter it also makes the earth heavier

Originally Posted by Twisted Tenon

... All life on earth is simply re using existing water.

and of course all the existing carbon, sulphur, sodium, iron ... well you probably get the picture now

Regards
SWK

Originally Posted by underfoot

Yep..sure does...overcrowding, overuse of resources, destruction of the natural environment, poverty, famine etc etc...it's a weighty problem...but won't add weight.

Whilst I stand to be corrected with my mathematics, if every one of the 7 billion residents of the earth were to have 0.4 km2 to live on, and grow food etc - they would ALL fit into Queensland. Doesn't sound like too much over population to me.

Just to put things into scale for you...

[ame=http://www.youtube.com/watch?v=HEheh1BH34Q]Star Size Comparison HD - YouTube[/ame]

I just love how much zoom out is needed to fit the hypergiant stars in...

Originally Posted by cava

Whilst I stand to be corrected with my mathematics, if every one of the 7 billion residents of the earth were to have 0.4 km2 to live on, and grow food etc - they would ALL fit into Queensland. Doesn't sound like too much over population to me.

Check your maths. Seven billion is a biiggg number. Queensland already has a population density around 0.4km2 per person (approx 4.5mill in 1.75mill km2). Perhaps Vic will have to take a few too.

Originally Posted by dabbler

Check your maths. Seven billion is a biiggg number. Queensland already has a population density around 0.4km2 per person (approx 4.5mill in 1.75mill km2). Perhaps Vic will have to take a few too.

Come State of Origin time, QLD gets as big as it wants and takes any one who can play a bit

TT

Originally Posted by Twisted Tenon

Come State of Origin time, QLD gets as big as it wants and takes any one who can play a bit

TT

Read the scoreboard TT.

Originally Posted by Twisted Tenon

. . .The way you and swk put it makes sense. All life on earth is simply re using existing water.

That is also not quite correct. The meteorites and cosmic dust that add to the mass of the earth contains hydrogen and oxygen. At some stage some of this combines into the existing water on earth. At the outer edge of the atmosphere a small amount of water vapour dissociates into hydrogen and oxygen. Quite a bit of the hydrogen escapes into space and a very small amount of oxygen does as well. So it's not a totally closed system

Originally Posted by cava

Whilst I stand to be corrected with my mathematics, if every one of the 7 billion residents of the earth were to have 0.4 km2 to live on, and grow food etc - they would ALL fit into Queensland. Doesn't sound like too much over population to me.

well thats a bit of a challenge! So I went and did a bit of googling and some maths.

Here's some rough numbers:

Queensland area = 1.7 million Sq km
So 7 billion people = a shade over 4000 people per sq km or about 250sq m each.
Thats about the size of a modern house.

So plenty of room for all the people of the world to _fit_ in QLD.
BUT 250 sq m is not enough area to grow food.
I found some data that said _for a western lifestyle_ about 7000 sq m is need.
SO...
About 142 people to a sq km is what we need for food, which is about 28 times more area than above. To feed everyone of the 7 billion at a level of the western world will take about 28 Queenslands in area...

and the continent sizes in "Queensland"s are:
Africa 17.8
Europe 6
North America 14.5
South America 10.5
Asia 26.2
Australia 4.5

So Asia almost will do it (and Asia actually includes India and the middle east) but no other continent by itself would come close to holding the worlds current population.

AND this doesn't include the land needed for mining and any other non farming needs and assumes all land everywhere is arable.

(all the above subject to having "deliberate" errors pointed out!)

Regards
SWK