One thing i dont understand about the first law of energy conservation

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HucktheForde
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the first law of energy conservation states that energy cannot be created or destroyed.

According to that , earth has been receiving energy from the sun in the form of heat and light for millennia. Doesnt that make Earth filled with gigantic amount of energy captured from the sun? So much that the light energy sent over here would light up the night and there would never be darkness? Since energy cannot be destroyed?
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Lucy._.R
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I'm not sure if this is correct, but my guess would be that although the energy isn't destroyed, it is simply radiated off of the earth. Heat rises, so the thermal energy will likely escape upwards for example through water dissipation etc. Also, the light that is reflected back into space from the sea surface makes up for a whole lot of the light that is absorbed.
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slightly_edited
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Have you learnt about global warming? If you did you'd know that energy can be trapped in the ozone or can be absorbed by aerosols in the atmosphere (dust, soot or other particles). Or in short some of the energy is reflected by surfaces of the earth. To answer you question on light, without going into too much science, it is either directly absorbed, directly reflected (which is the reason earth seems to glow from outer space) or the light it converted to heat energy and the above happens.

You've only mentioned part of the law. It actually goes as - Energy cannot be created or destroyed it can only be transferred from one form to another.
If you understood this you'll know that some forms of energy can be seen (light) some cane be felt (heat) , then you have kinetic (movement) etc.
Hope this helped and I might be wrong but this is what I have learnt and applied all along.
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tHe237046
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You forgot the part where it says energy can only be transferred between its respective forms.

All the light energy, eventually gets absorbed by living organisms (plants and other biological forms of life)
which use light energy for photosynthesis. Rest of it is converted to heat, absorbed by our water, our environment, etc.

1. Light used in photosynthesis, and other organisms absorb it to create nutrients and build themselves up.
2. Light turned to heat, absorbed by the water on earth (THE WATER CYCLE)
3. Light turned to many other forms of energy.

Really
the way to think of it better is like this:

Imagine a list that gets permuted:
 

(a,b,c,d) \rightarrow (b,d,c,a) \rightarrow (c,a,d,b)
Energy gets transferred, but the total energy remains constant.
Of course, energy can concentrate in large amounts somewhere, but it all remains constant.
The list above, it permutes, but the lists length is the same, its always permuting though.

Yes, for millenia the sun has been heating this little rock but for millenia weve also had trees, plants, animals, humans, absorbing that energy to make organic materials (tissues) and then dying themselves.
Last edited by tHe237046; 1 year ago
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Mr Wednesday
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(Original post by HucktheForde)
the first law of energy conservation states that energy cannot be created or destroyed.

According to that , earth has been receiving energy from the sun in the form of heat and light for millennia. Doesnt that make Earth filled with gigantic amount of energy captured from the sun? So much that the light energy sent over here would light up the night and there would never be darkness? Since energy cannot be destroyed?
As the posts above highlight, Earth both receives and emits light and is roughly speaking in equilibrium with the Sun, so radiated energy in = radiated energy out, though in different parts of the spectrum. There is some highly non-linear physics here as well, power radiated by a body is proportional to Temperture T^4 so if the Earth warms up a little, it becomes better at radiating energy which cools it down and helps to keep things approximatly constant.

Some of that solar energy does get captured, e.g. building more complex chemicals in photosynthesis, but the total mass of life (and life derived material like coaland oil) on Earth is a very tiny fraction of the total mass. There are other processes warming the Earth as well, mostly from radioactive decay, but tidal friction also delivers a little bit of the rotational energy of the moon to the Earth.
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