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/sci/ - Science & Math

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2204407 No.2204407 [Reply] [Original]

Do closed systems exist?

It's mentioned in the second law of thermodynamics, but what is it really? I've heard even the Earth isn't a closed system since it receives energy from the sun. Is the solar system even a closed system? I would say for practical purposes yes, but it does receive some radiation from external sources, I can't say with any certainty that this is not meaningful.

>> No.2204426

no

>> No.2204428

The universe is the only truly closed system that I know of.

>> No.2204431

You can see stars in the sky, so even if it's an irrelevant amount of energy, that's something right there.

>> No.2204434

I don't think anything but the universe itself is actually a closed system but there are many things that can be considered closed systems for practical purposes and that's all that matters. Pretty much any law of science isn't exactly true but is good for practical purposes. Newton's second law for example is not true. But under most conditions it is an excellent approximation.

>> No.2204437

>>2204428
What about black holes?

>> No.2204446

Four answers, each better than the last!

So now then, can you give me some examples of context-valid closed systems?

>> No.2204457

>>2204446

Something inside of a thermally insulated closed chamber

>> No.2204458
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2204458

Chemist here: if you want to get super technical - it's absolutely impossible to have a perfectly closed system because you're always going to have a greater "surroundings" to deal with.

However, for all practical purposes, you can create systems that are effectively closed systems if you define the boundaries of your system as the walls of a good insulator.

Token bomb calorimeter picture, as it's the best example.

>> No.2204470

Wait, when a system is said to be closed, is it assumed that energy can escape the system but not enter?

>> No.2204479

>>2204470
Scratch that I guess. It's probably due to me having a limited understanding of entropy.

>> No.2204480

>>2204470
Energy is conserved in a closed system.

>> No.2204481

>>2204470
A closed system is one where energy is conserved.

>> No.2204497

>>2204480
>>2204481
This frightens me.

>> No.2204523

>>2204497
Hivemind alert! Hivemind alert!


Also, the universe is a closed system.

>> No.2204545

>>2204480
>>2204481
Energy is actually conserved in any system with homogenity of time. Learn to higher physics bros!

>> No.2204566

>>2204523
You would think so. As far as we can observe energy does not enter or leave the universe. It might be like a teenager that leaves the house when no one is watching. We wouldn't really know.

I think I know a little bit more about entropy now, but I would still like some practical examples (I assume practical applications exist. In this I may be subtly or grieveously deluded.)

>> No.2204578 [DELETED] 
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2204578

>> No.2204593
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2204593

>>2204545

>> No.2204640

>>2204497
the solar system is a space ship, so it is a closed system

>> No.2204710

>>2204566
Entropy is a measure of "useless" energy. You've most likely seen the equation...

∆G = ∆H - T∆S

If you think about it conceptually, it basically translates to...
Free Energy = Total Energy - Unusable Energy

This formulation is particularly useful for thermodynamic thought. If you dabble in statistical mechanics they treat entropy differently, but this should suffice for your interests regarding entropy.

>> No.2204927

>>2204428

exactly anon, if conservation of energy is real then this universe is the closed system

>> No.2204947

>>2204927
Is this well enough accepted that it's worth falsifying?

It may be possible to pose thought experients that questions the universe's merits as a closed system. I suspect primarily that relativity will fuck with the assertions of thermodynamics.

>> No.2204982 [DELETED] 

>>2204947

you will have to do some homework
but our DNA has a tail like section in which a fragment of it breaks off every time the cell divides until you get to a point in which there is no more of this tail and then the cell will die

cancer has a tail that doesnt shorten the cells can divide infinately

>> No.2205006

>>2204947

i read an article in the New Scientist recently which brought accross the possibility that conservation of energy is not real. if that is true then the universe is connected to whatever it originated from or to other universes.
i just remembered something from 'what the bleep do we know' where fred alan wolf was saying that atoms appear and disappear from our universe

>> No.2205017
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2205017

>>2205006
>New Scientist
>What the Bleep do We Know
>reputable sources

>> No.2205033

>>2205017

i know what the bleep isnt the best but new scientist is ok just to keep up on the current issues.

i know its not a scientific journal but interesting non the less

>> No.2205037

>>2205006
>atoms appear and disappear
Yeah they do? This is because energy -> matter -> energy
Energy turns into matter then back to energy. Vacuums have particles constantly appearing, but an anti-particle that goes along with it. Then they both annihilate eachother and turn back into energy!

>> No.2205066

>>2205037

wait what... what is making atoms from pure energy in todays universe????

>> No.2205678

>>2205066
Quantum fuckatrons I suppose.