/sci/ - Science & Math

[Anonymous No.6577699]

Hey /sci/,

If energy can't be created nor destroyed, does that mean that the amount of energy present in the universe is constant?

Not even trying to troll or anything, I'm legitimately curious about this. I though about this last nigh while trying to sleep.

[Anonymous No.6577704]

>>6577699
no.
Energy conservation has been disproven for a century now.

[Anonymous No.6577706]

>>6577704
o rly ?
Source plz ?

[Anonymous No.6577710]

>>6577706
<span class="math"> E=mc^2 [/spoiler]

[Anonymous No.6577714]

>>6577710
>i'll just put an equation, they'll figure i am too intelligent for them
This equation explains matter is energy. Try another one.

[Anonymous No.6577716]

>>6577714
nope. try again.

[Anonymous No.6577718]

>>6577699

[Anonymous No.6577719]

>>6577716
OK. First fucking Law of thermodynamics. I'm waiting for you to prove it is false.

[Anonymous No.6577725]

>>6577719
E=mc2

[Anonymous No.6577726]

>>6577699
if your lagrangian is invaraint under t-transformation then energy is conserved.

[Anonymous No.6577751]

>>6577699
>does that mean that the amount of energy present in the universe is constant?

Yes. Ignore the moron.

[Anonymous No.6577760]

>E=mc2
OP, matter can be converted into a fuckton energy, thus increasing the amount of energy in the universe (and subsequently decreasing the amount of matter).

[Anonymous No.6577767]

>>6577760

No, that's not what that means at all. The mass IS energy, essentially.

[Anonymous No.6577771]

>>6577760
Why do you consider matter and energy are different things ?

[Anonymous No.6577777]

>>6577771
Because I've only got a high school education

[Anonymous No.6577784]

>>6577777
>i learned this shit in high school
where did you go to high school ?

[Anonymous No.6577786]

>>6577784
When did I say I learned this shit in high school? I meant that I'm ignorant to the topic because the only education I have is high school.

It was a self degrading way of admitting my mistake

[Anonymous No.6577787]

>>6577784
Finnish high school teaches this. Or at least, I was taught that in high school.

[Anonymous No.6577792]

>>6577784
>>6577786
Also I took astronomy as a junior, my teacher knew his constellations but he seemed iffy on math/physics. Went to HS in upstate NY

[Anonymous No.6577795]

>>6577786
I said I did, sorry you misunderstood.

[Anonymous No.6577796]

>>6577771
because classically they are.
Certain people will say that energy is not conserved during a nuclear reaction.

[Anonymous No.6577800]

>>6577787
>>6577792
>>6577784
Officially stating that european school teach science better than amercian's.

[Anonymous No.6577801]

>>6577795
My bad. I never took physics in HS because there was no teacher. I managed to teach myself some basic newtonian shit, but that's about it.

[Anonymous No.6577803]

>>6577777

[Anonymous No.6577804]

>>6577800
> what is sample size

[Anonymous No.6577808]

>>6577699
Yes, that's one of the statements of the 1st law

[Anonymous No.6577816]

>>6577804
3 !
I can also state that at least half of european people are Belgian.

[Anonymous No.6577853]

>>6577796
That's retarded.

The energy released from nuclear fission/fusion is provided from a type of potential energy related to the strong and weak nuclear forces. This potential energy just so happens to be related to the mass difference between the source and products.

[Anonymous No.6577856]

>>6577853
Tough.
That's how it goes
http://en.wikipedia.org/wiki/Nuclear_reaction#Energy_conservation
> In a nuclear reaction, the total (relativistic) energy is conserved.
note the qualifier

[Anonymous No.6577865]

>>6577856
>That's how it goes

Except that specifically says the opposite.

[Anonymous No.6577868]

>>6577856
>note the qualifier

That's a clarification, not a qualifier. Note the parentheses.

[Anonymous No.6577971]

Years ago the law of conservation of energy and the law of conservation of matter were widely accepted. With the discovery of nuclear fission, it was learned that, as Einstein predicted, matter could be converted to energy. Later it was found that photons could collide at high velocity an produce an electron and positron, matter. (or matter and antimatter. It doesn't really matter.) So the two theories were combined into a theory of conservation of matter and energy. Some choose to say that matter is a form of energy. (Again it doesn't matter. Same idea expressed with different words. Like matrix multiplication. AB. Left multiply B by A or right multiply A by B? Row operations or column operations? You get the same answer either way. It blows my mind. )

[Anonymous No.6578015]

>>6577699

> energy can't be created nor destroyed, does that mean that the amount of energy present in the universe is constant?

Actually NO, in general. This is kind of surprising. The first of your statement is basically a local conservation law. It has the form: four-divergence of a four-current = 0 (sorry, no latex I'm on phone.) To pass to the second statement, which is a global statement, you need some extra assumptions. The first is that the spacetime has topologically trivial and asymptotically flat spacelike slices (this is not obvious at all in General Relativity!); this is needed so you can even define the integral of the energy density over all space to define that energy. The second is that the energy flux goes to zero fast enough to infinity (faster than |x|^-2 or something I think) to make a certain surface integral vanish. This also is a delicate point even without gravitation.

If you are interested, any advanced textbook on electromagnetic field theory will discuss the relevance of all of this is detail.

[Anonymous No.6578043]

>>6577971
Thanks a lot. I didn't think of that, even though I kind of knew it.
>>6578015
Well, thank you too for the detailed reply, but I didn't understand much, as I have no idea about physics. But yeah, thanks.

[Anonymous No.6578053]

>>6577699
>does that mean that the amount of energy present in the universe is constant?
No, retard, because eventually there won't be enough energy to continue the process of star formation--that's when the universe "dies".

[Anonymous No.6578056]

>>6577771
Matter has a different definition than energy, you're thinking about about mass.

[Anonymous No.6578063]

>>6578053

It's called Heat Death

[Anonymous No.6578078]

>>6578043
sorry, didn't mean to drown you in technicalities. Sadly, this kind of stuff requires some basic groundwork in physics and math. The proof of this is the absolute incompetence of the other poster you thanked. If you care about understanding this, leave this board immediately.

If you want to bathe in retarded popsci delusions, stay.

[retarded popsci delusionist No.6578102]

>>6578078
Can you cite one example of the law of conservation of matter and energy not working on earth? I know it disagrees with cosmology theories but it has always been experimentally verified so far as I know. It is also useful in science, engineering and debunking claims of perpetual motion machines.

[Anonymous No.6578103]

>>6577699
>If energy can't be created nor destroyed, does that mean that the amount of energy present in the universe is constant?
Yes.

[Anonymous No.6578113]

>>6578102
"conservation of matter" does not mean anything.

Conservation of energy is valid locally, which is equivalent to time translation invariance. It is not the same as global conservation. Even defining "all the energy in this system" is nontrivially problematic.

[Anonymous No.6578118]

>>6578113
This.

Look up "Noether's theorem."

[Anonymous No.6578168]

>>6578118
Thanks. I need to look into that more.

[Anonymous No.6578176]

>>6577699

can an infinite universe be a closed system?

[Anonymous No.6578203]

>>6577777
>77777
Nice sevens

[Anonymous No.6578205]

>>6578053
You are the retard. The amount of energy in the universe is constant. What you are refeering to, the heat death of the universe, will be due to all that energy spread in a fuck huge volume, and thus appearing scarce locally.

[Anonymous No.6578215]

>>6578176
We don't know if it's infinite, but it's expanding.

[Anonymous No.6578900]

>>6577699
The further you go in science you will have a lot of questions like this. The best answer (I think) is we live in a fairly complicated place and people develop models to describe and predict their world. These models work for just about everything. Where the models fail is where the smart people are working.
In regards to your question, because of E=mc^2 it is the law of conservation of matter and energy.

>A model is a lie that helps you see the truth

[Anonymous No.6578903]

>>6578205
> What you are refeering to, the heat death of the universe, will be due to all that energy spread in a fuck huge volume, and thus appearing scarce locally.
don't call people retards when you don't know what heat death is.

[Anonymous No.6578904]

>>6577725
That just proves matter is energy and visa versa. Mass-energy is conserved.

[Anonymous No.6578918]

>>6577699
If the universe is an isolated system, then yes. Otherwise no.

[Anonymous No.6579674]

>>6578904
1) the formula is incomplete, as stated
2) matter is not energy
3) matter is not mass
4) energy is not mass, no fucking way, stop repeating this.
5) MASS IS NOT CONSERVED. MASS IS NOT CONSERVED. MASS IS NOT CONSERVED.
>b-but hurr durr can you cite one single examp...
NUCLEAR REACTIONS

>but you see the definition of mass is this one [insert incorrect/newtonian/inconsistent definition here] so

no

mass is not conserved.

Jesus christ.

[Anonymous No.6579686]

>>6579674

Please just read this:

https://en.wikipedia.org/wiki/Mass-energy_equivalence

[Anonymous No.6579690]

>>6579686
god fucking dammit it's wrong. You need very little relativity to understand it.

E^2 = m^2 + p^2 (natural units because fuck you)

where are they equivalent? What is the symmetry that has mass as its noether current?

[Anonymous No.6579696]

>>6579690

[Anonymous No.6579854]

>>6579696
wow what a fucking valuable counter argument.

because going to school and attending an introductory course in relativity is just a tad too hard.

again (sigh):

mass is the square root of the absolute value of the square of the four-momentum.

Consider the annihilation of an electron-positron pair into two photons.

Mass before.

electron mass + electron mass (this is a lorentz scalar which is indipendent of reference frame and state of motion of particles)

Mass after.

for light E = p or equivalently four-momentum is lightlike. Because it's light, get it? This means by definition p^mu p_mu = 0. So the mass is zero now.

> inb4 relativistic mass

[Anonymous No.6579859]

>>6577699

Yes the total energy of the Universe has always been what it is now, and will always be what it is now, 0.

[Anonymous No.6579864]

>>6577699
>energy present in the universe is constant
yes

energy MUST be a constant when thinking about the universe as a four dimensional object.

But you're probably asking if the amount of energy from one planck frame to the next (a planck frame is, painfully simplistically, how the framerate of the universe is measured where a panck frame is a snapshot of an instant of the fourth dimensional universe, measuring one planck length). In this case, no it isn't.

This is because the universe is not 3 dimensional with 2D waifus living inside of it. it is four dimensional. we are also four dimensional: we see 3D snapshots of our four dimensional selves.

Reference the movie Primer, which is way more accurate than almost all films about time travel. Unless one properly thinks about the universe as a four-dimensional object containing four dimensional mass (that interacts in 3D snippets), time travel and likewise, constant energy dont make sense.

[Anonymous No.6579874]

>>6579864

>(a planck frame is, painfully simplistically, how the framerate of the universe is measured where a panck frame is a snapshot of an instant of the fourth dimensional universe, measuring one planck length).

this has literally no connection with physics whatsoever. What the fuck are you on?

[Anonymous No.6579888]

>>6578903
But he's right...

[Anonymous No.6579890]

>>6579859
>implying there is negative energy in order to make it zero

my sides

[Anonymous No.6579894]

>>6579890

>not knowing that +ve mass-energy is cancelled out by -ve GPE if our Universe is flat, which according to all modern observations, is the case

[Anonymous No.6579899]

>>6579890

http://en.wikipedia.org/wiki/Potential_energy#Gravitational_potential_energy

[Anonymous No.6579900]

>>6579874
I tried simplifying planck time in a way that makes sense to me; sorry it doesnt work for you. Why is there any reason to be upset?

>>6579888
im too hungover to figure out who is arguing for the ending of this universe to be a, "heat death," but isn't that the less popular theory these days?

No one on this board can properly disprove a heat death themselves, but my astrophysics professors were more in favor of a rather boring, "cold death," due to proton decay.

kinda anti-climactic.

[Anonymous No.6579904]

>>6579899
>>6579900
>1381844602777.jpg
holy shit

[Anonymous No.6579910]

>>6579899
>>6579900

[Anonymous No.6579911]

>ctrl+f "isolated"
>ctrl+f "closed"
>two results

Come on, /sci/, can we at least pretend we know what we're talking about? Mass-energy is only conserved in a closed system. If the universe is a closed system, energy is conserved, if it is not then energy is not conserved.

The general consensus is that the universe is an open system and that new energy can be created by creating "negative" (potential) energy as a cost. No one has proved this yet, but it's what a physicist will tell you.

[Anonymous No.6579912]

>>6579911

Yes and the new mass-energy than can be created is cancelled out by the gravitation potential energy, hence the sum energy of the Universe being 0.

[Anonymous No.6579917]

>>6579912
Correct.

[Anonymous No.6579918]

>>6577710

<span class="math"> E=\frac{1}{2}m v^2 [\math][/spoiler]

[Anonymous No.6579922]

>>6579900
time is not granular at the planck scale nor is there such a thing as "planck frames" or any kind of frames for that matter. This is not simply a misinterpretation, this is literally something that does not exist in physics.

I have no idea why you would believe this, but for the sake of discussion I challenge you to cite a single peer reviewed paper that discussed this.

[Anonymous No.6579923]

>>6577710

<span class="math"> E=\frac{1}{2} m v^2

>hurr durr so when things move total energy is going to be decreased.[/spoiler]

[Anonymous No.6579930]

Matter used to be defined as that which has weight and takes up space. When space exploration became a possibility, the definition changed. Matter became that which has mass and takes up space. Matter may have become an archaic term but it has meaning. Just wanted to clear that up for those who don't understand it.

[Anonymous No.6579931]

>>6577710

<div class="math">
E=\frac{1}{2}mv^2
</div>

>hurr durr when matter is accelerated energy of the universe is decreased.

[Anonymous No.6579935]

>>6577699
This too interests me. If the Universe is indeed expanding, does that mean that there is less energy per square metre or something? Could the Universe ever theoretically run out of energy?

[Anonymous No.6579978]

>>6579859
That is a cool idea, that gravitational potential energy is the negative of the energy in mass. But then what of energy stored in charge, spin, and other characteristics? Maybe there are energies we don't even know about.

[Anonymous No.6580008]

>>6579978

Conservation of spin, charge, etc. handles that.

[Anonymous No.6580014]

>>6577699
not only is the total amount constant, it's possible that the total amount is zero

[Anonymous No.6580022]

>>6577699
there are so many retards in this thread... i started writing responses to correct people, but its just too much.

[Anonymous No.6580039]

>>6580014
So, there is no energy in the universe. I never would have thought of that!

[Anonymous No.6580049]

>>6580039
I didn't say no energy (that would be nonsensical), I said the TOTAL energy was zero.

[Anonymous No.6580065]

What is the standard definition of energy? All I've ever seen is "work done". I don't know what "work done" or "energy" is referencing.

[Anonymous No.6580084]

>>6580065

"It is important to realize that in physics today, we have no knowledge what energy is." - Feynman

The best description we have of energy is that it's a thing, a quantity, which in every interaction we have seen, is conserved.

[Anonymous No.6580097]

>>6580065
>>6580084

energy is perfectly well defined as the time component of the noether current associated with time translations. If you don't find this intuitive, don't fucking go around spouting that "noone really knows what it is" bullshit.

enough of this "I don't know this therefore it is a great mistery of science" nonsense.

[Anonymous No.6580114]

>>6580097

Have you finished your sperg rant now?

Noether's theorem has nothing to say about the nature of this quantity we called energy, it only can be used to argue for the conservation of energy.

The question is, what is it that is being conserved?

And also, what we don't know is certainly a great mystery, but clearly as an autistic undergrad, you wouldn't be capable of fathoming this.

[Anonymous No.6580128]

>>6580049
Bad joke.
Sorry about that, chief.
It seems to me that energy is usually proportional to some quantity squared. So there may be underlying quantities that cancel in total while creating other quantities that still conserve the total energy.
>>6580065
Energy is "the ability to do work." Roughly, work is exerting a force through a distance in the length, mass, time view of physics, force being what is needed to accelerate mass. That is sort of a Newtonian view of the universe. That view holds on a small scale the same way smooth curves approach being straight line segments if you make the segments small enough. So Newtonian physics is sort of like looking at the small picture while relativity looks at the bigger picture, or at least what we think the bigger picture looks like. It's hard to see it all at once when you're up close.

[Anonymous No.6580158]

>>6579922
thanks for not trolling, cursing or asking about Bane.

While I look for a peer-reviewed article, a simple Google search reveals plenty about Planck-time. An article from Cornell comes up:

http://arxiv.org/abs/1311.3135

>...the standard description of spacetime...spacetime with a spectral dimension of two.

But I would have to dig deeper than a 0.19 second Google search. Something you should look into as well.

[Anonymous No.6580176]

>>6580114
>The question is, what is it that is being conserved?
this is the most retarded sentence on sci at this moment

[Anonymous No.6580380]

>>6579696
For a quantity to formally be conserved, it must be associated with a Noether current. Since mass is not associated with any such currents, it is not a conserved quantity.

Mass-energy equivalence is also not a formal equivalence, but a note that energy content can lead to an increase in mass, as in the case of nuclear binding energy or the energy content of chemical bonds. In this way, energy and mass are equivalent in that there exist circumstances where energy may be treated as mass, but they are not equivalent in that one is always identifiable with the other, as is clearly indicated by the full relativistic energy content of an object.

[Anonymous No.6580395]

>>6577784
I went to a public high school in America and my physics class covered special relativity.

[Anonymous No.6580925]

>>6578053
>Heat Death
>Energy destroyed
>

That theory's all about energy spreading out infinitely as the universe grows. You know that, right?

It's like if someone released a bunch of gas into a chamber with infinite volume. At first it's concentrated, but eventually it's so spread out you can't even detect it anymore.

Here's hoping energy is somehow affected by gravity.

[Anonymous No.6580930]

>>6580925
that's wrong too.
heat death is that there's no potential difference to facilitate change.
Irreversibility (entropy) keeps adding up until nothing can happen.