/sci/ - Science & Math

What are you talking about? I think you are the one thats misguided.

>Implying glass is a slow-flowing liquid

>there's no evidence
>mfw

>>2986817

No, he's actually right. The first and second laws of thermodynamics only apply in closed systems. The Earth isn't one, there is a constant influx of energy from the Sun/

>>2986817


The Laws of Thermodynamics apply to closed systems...

Ever heard of... Oh I dunno... The motherfucking Sun?

the 'law of averages'

ie. this guy hasn't hit a home run in a week. the law of averages says he is due!!

>magnets
>homeopathy
>electricity
Rage thread?
Rage thread.

http://www.youtube.com/watch?v=_c6HsiixFS8
http://www.youtube.com/user/dbootsthediva

>>2986836

Dear God I remember watching that for the first time. Pic related.

>>2986827

Oh my god this...

Watching Baseball with friends and I hear it all the time... Even from the commentators.

>>2986836


http://www.youtube.com/watch?v=C0c5yClip4o


This is worse.

>>2986825
Cool, well since there's no such thing as a closed system, the laws of thermodynamics are false. Thanks for clearing that up.

>implying you'd freeze in space
>implying the effectiveness percentage of a birth control method = the number of times you won't get pregnant using it and you'll get pregnant the remaining percent.

>implying you can't get pregnant standing up because gravity

>>2986848

The Universe is a closed system.

Thanks for playing.

>implying fetuses are not human lives
>implying God doesn't exist cause he can't be proven, but accepting more complicated explanations that also can't

just gonna leave those two here

>>2986848

Colossal dumbfuck detected.

Seriously, the fact that the Earth is not a closed system doesn't mean they don't exist. The Earth isn't a walrus either, but it doesn't follow that they don't exist.

>>2986860

>Black Holes are marauding godless killing machines that devour everything

>>2986846
disease = transforming our energy into another state and homeopathy can transform it back to cure it my manipulating string theory?

wtf am i watching...

>implying voltage=current

>implying Bigfoot doesn't exist because no bones have been discovered. They're obviously cannibals who eat each other, bones and all.

>>2986853

In high school I fucked this chick.. A virgin... who assured me she was on birth control. (Yeah I was fucking stupid for forgoeing the condom anyway, I know.)
She insisted on cowgirl style and I obliged, thinking that shit, "she's a virgin, let her control it."
The next day she tells me that she's not on bc but that I shouldn't worry because we did it cowgirl style and she couldn't get preggo due to gravity.

mfw most anxious 2ish months of my life. I am so glad nothing came of it...

>>2986884
>high voltage is dangerous! omg
i wonder what these people would do if they found out stunguns are approaching something stupid like 30 million volts

then again i wonder if these people even know what current is or a "milliamp"

>>2986854
Either you're suggesting that the universe is provably finite, or you are suggesting that infinity is closed.

>>2986864
Also, the earth is not ellipsoidal. Ellipsoids are only ideal models. They do not exist outside of models.

>implying any string theory is a scientific theory.
>implying that a majority of physicists accept a form of string theory as anything other than a festering pile of shit.
>implying a theory is just a guess, or even a single tested idea and not a general descriptive model of reality.
>implying that finding one apparent disagreement with a theory makes the theory completely wrong.
>implying that disproving a competing theory is tantamount to evidence for another theory.
>implying that absolute certainty exists at all in science

I mad.

>implying cutting/ shaving your hair makes it grow faster

>Why are there still monkeys if they evolve into humans? Evolution doesn't work.

>the sun is not simple combustion

>>2986899

I've actually wondered what the purpose of the super high voltage in stun guns/tasers is. I mean the intent is to deliver a specific amount of current into the body right? so what's the point of jacking the voltage up so high?

>>2986922

It's easier to sell to government agencies if you can offer them absurdly high numbers for their dollar. It doesn't matter if those numbers mean anything.

>Implying the laws of thermodynamics apply to the Earth.
i.e.,
>Implying baby Jesus creates fossil fuels to keep the US economy going without a peak of oil production.

>>2986922
Two hoses of the same diameter have different pressures, which one expels water faster?

>>2986849
because the convective heat transfer coefficient is so low right?

>>2986970

eh, it's been a while since i took a circuits course but iirc that isn't the way current works.

>>2986904
>>implying that absolute certainty exists at all in science
Are you absolutely certain that it doesn't?

>>2986849
>implying you wouldnt freeze in space, at least in areas not lit by the sun

L2 radiative heat transfer

>>2986997

I see what you did thar.

>>2986997
The existence of uncertainty is certain.
The existence of certainty is uncertain.

>>2987013
fullretard.jpg

Space is a near vacuum, you are perfectly insulated. There is no medium for heat to escape your body. You'd freeze over millions of years, but you'd asphyxiate first.

>>2986846
There are no words in the english language to properly express how mad I am.

>>2987031
actually by earth you'd probably roast to death because the sun would be hitting your body and the energy would only be very slowly radiated away by photons. i forget the process name for this but not conduction and not difussion

>>2987031
How exactly does the sun warm our planet?

>>2986810


>implying that humans would develop a phenomenological and unquestionable theory based on something that did not apply on the only planet they ever knew or experienced.

>>2987031


true... but the earth itself is literally outgassing all the time.


in 10,000,000 years there wont be a single atom of Helium left on this planet (assuming we keep digging up petroleum)


it literally escapes the atmosphere.


it forms no compounds. it is mixed in with petroleum. that is where we get 100% of our Helium.


when it evaporates, its gone forever and never comes back.

the atmospheric Helium content never increases.
these are just simple logical thought points you can use, but this is established fact.

>>2987060

iirc we have an atmosphere

>>2986846

...........

>>2987060
Energy from photons from the fusion reaction.
Your body does not emit photons, so you will not lose energy in space.

>>2986970
>implying that pipes all have the same diameter
the analogy is: current is how much water flows, the pressure is voltage. In the case of tasers, the diameter of the pipes are small, but you're saying that they're the same diameter, which is correct for a fixed current. however, you can't just increase water pressure(voltage) without also increasing water flow(current) unless you reduce the size of the pipe. anyways im through with the shitty analogy's. lern 2 electromagnetism noob

>>2987079
i think you got some derp in your herp there retard.

>>2987079
Bitches don't know about infrared

>>2987079
I lol'd
7/10

> Maxwell's equations are correct

>>2987073
>in 10,000,000 years there wont be a single atom of Helium left on this planet (assuming we keep digging up petroleum)

...Alpha decay will stop in 10 million years? I can start eating plutonium again! YES.

>>2987100
every time i spoon, i think i'll get that bitch some infrared, bitches love infrared.

>>2987079
yeah you do, and yes you will. I took heat transfer last semester, and all matter radiates em waves as a function of its temperature. This doesn't matter at all on earth, because any object you consider is surrounded by other objects doing the same thing, and further, having their temperatures raised by the object you are considering, and radiating that much more em waves to the object. In space, if you are not in sunlight, you will be losing heat through radiation at a high rate because you are not surrounded by anything radiating it back.

>>2987119
>all matter emits photons

Then why can't you see in the dark, retard?

>>2987127
there's a reason it's called the "visible" part of the spectrum

>>2986827
the law of averages means initial predictions before his losing streak were wrong

>>2987127
>troll detected

>>2987127
I guess I mistyped when I said "yeah you do" to start off, you emit em waves, but at a lower(I believe) none visible wavelength, but whatever dude.

>>2987127
6/10, not bad. I know a lot of people that actually would fall for this nigger logic.

>>2986918

>>2987112


>left ON this planet


true. the earth is full of radioactive material that is constantly decaying and emitting radiation of various forms. indeed, the earth's core gets MOST of its heat from this, NOT from gravitational tidal forces (yes, learned it in a geology course).


but that exceedingly small proportion of alpha particles, relative to the helium trapped in natural gas, is so vanishingly small that no human instrument would ever be able to detect it.


seriously all of the radioactive material IN the earth, all the way to the core, emitting alpha over its entire decay lifetime, and all of the daughter nuclides, would account for about 10^-19 percent of the helium that humans have ALREADY blasted into the atmosphere...


there is no major downside (helium has no negatives at atmosphere pressure/temp, not a greenhouse gas, etc)

>>2986899

>implying that grounding 100,000 volt low current power lines with your body is safer than shorting the >250 amp 12.5 DC car battery

>>2987169
that is 100% true.

your an idiot

>>2986922
It's because while skin really only has a resistance of around 500-1M (depending on how clean the surface is) ohms; shirts, jackets, and other things usually have a much higher resistance. And you are rarely going to come across an instance where you are going to be able to tase someone directly on their skin with both contacts having an even connection.

Plus if you put the voltage high enough, when they test-fire it, it makes a cool buzzing noise and emits sparks.

>>2987187


>implying that shorting a car battery to your testicles, though exceedingly painful, does not kill you are burn your testicles into worthless chunks of flesh within seconds

>implying that grounding a power line wont kill you almost instantly.

>>2987188

so the super high voltage is just guaranteeing a small amount of current through a large resistance?

also I was thinking a small battery probably has a max current output anyway, so ramping the voltage up to 50MV doesns't change much.

>>2987193
That's why the battery feeds into a capacitor, which can emit a higher output in a very short amount of time.

>>2987193


batteries behave like capacitors with variable resistors associated (internal resistance) that increases as the charge is used.


some battery types (specifically NiMH) have very low initial internal resistance (which increases as they discharge).

so too, do lead acid batteries.


these types of batteries are capable of discharging extremely high currents at their rated voltage for at least a short period of time.


alkaline and Li-Ion batteries, on the other hand, have much larger internal resistance that does not vary as much over their discharge cycle.


they never put out super high current.


but go out and grab a 1600 mAH NiMH AA form factor rechargable (usually rated at 1.35 volts)

they put out about 15 amps when shorted, and the current drops quickly after a short period.

>>2987169
You could increase the voltage of the car battery to 100,000 volts. Which would be more dangerous then, HUH??? The power lines. Why?

MORE CURRENT MOTHERFUCKER.

Seriously, stop breathing.

>>2987192
your an idiot confirmed.

raised a double nigger.

>>2987169
>250amp car battery

Does that even start your car? My battery is 900 amps

by the way, just in general...
>your an idiot.
>your an
>your
>should be you're

>>2987224


I drive a 2.0 4 cylinder turbo..


what do you drive? a 7.9 liter diesel or something?

>>2987225
your an idiot

double nigger

newfag

>Implying battery acid is potent enough to eat a manhole-sized hole in the hull of the Nostromo

>>2987230
>implying a turbo would make the car need more amperage to start

No, a V6.
Have fun starting anything with 250 amps when it goes below 50F

>>2987230
>7.9 liter diesel

FUCK YREAH

Umm, open systems are part of thermodynamics. You seem to have confused one small part about increasing entropy with somehow being the entirety of thermodynamics. Yes, you can decrease entropy with the addition of external energy -- that's part of thermodynamics. What the fuck.

>>2987233
The acid could have been catalyzed by enzymes produced by the alien.

>>2987252
Batteries aren't nearly as cool as xenomorphs.

>People believing Newtons 'laws' are correct
: 3

> Light stays at the same speed, no matter what medium

Yes ive had people tell me this.
"But light is a constant speed no matter what!"

>>2987193

P = I V

Power = Current * Voltage

Obviously if the same amount of current drops to a lower potential it's going to deposit more energy.

>>2986854
Aside from this, which we rely on being true for a whole mess of assumptions, there are formulations of the laws of thermodynamics for open systems.
Rather than trust me on it, let's check "Advanced Engineering Thermodynamics 3rd ed." by Adrian Bejan.
He seems reliable- his book is the most widely used engineering thermodynamics text today, and he is one of the 10 most cited thermodynamics authors ever published by Wiley, Pearson, or Thompson publishing.

Page 20, "The first law for open systems"
dE/dt - Q_dot -W_dot + Sum_in(m_dot(e+Pv)) - Sum_out(m_dot(e+Pv))

Page 60, "The second law for open systems"
s'''_gen = rho*(Ds/Dt) + div dot q/T greater than or equal to 0

>>2986825
>>2986826
So, good news, the laws of thermodynamics haven't failed us yet.
A better argument would be to try to find some sub-atomic scale where there's enough ambiguity between [your favorite model] and the Standard Model, but frankly if I can't hit it with a hammer, it's too small to be in my field of work. Freakin' leptons.

>>2986810
/sci/ has intelligent conversations about science or math

>>2987295
So I guess a popular misconception is that Thermodynamics is axiomatic and not a well established law.

Another misconception that irks me is when I see the D'Alembert solution to the wave equation presented as the full general equation. It is the right equation in many cases, but the separation of variables solution can express mode shapes not in the D'Alembert solution.

The laws of thermodynamics do apply to the Earth.

E.g. "In a closed system, entropy rises"

So, if Earth obeys this law, either Earth has rising entropy or it is not a closed system. It is not a closed system, so it does indeed obey this law.

>>2987313

Can you give an example problem?

>>2987274

Light does move at a constant speed, no matter the medium. There's just complex quantum mechanics at work when photons move through mediums, being absorbed and re-emitted by particles within the medium.

At least that's what I heard.

>>2987333
and by this i mean, can you create a separable solution that can't just be transformed from the general d'alembert solution?

>>2986904
>mfw you have no fucking understanding of what string theory is or where it came from

>>2987339

it moves at a constant speed within each medium, i guess you could say. but the speed changes depending on the medium.

Not popular, but pissed me off - some creotard:
>Newton's quantum physics is still valid while evolution theory is changing all the time

>>2987333
See the picture for the equations...I'm the lame guy that hasn't learnt jmath yet.
I should clarify that the D'Alembert solution is to the 1-D wave equation and is the full, general, solution to the 1-D equation. It does not fully express the 3-D solution to the wave equation.

So really I guess it's not the D'Alembert solution that irks me. It's the assumption that a 1-D solution is always sufficient.

>>2987342
So no, not really. I consider the D'Alembert solution to be what I consider people to 'the classic 1-D D'Alembert solution'.
The 3-D extension isn't actually much different, but as per my previous post, it's more the 1-D vs. 2-D vs. 3-D assumptions that get me.

So I retract my original stament; you are correct that the D'Alembert solution is the general solution to the wave equation. My original statement was poorly worded and #notintendedtobeafactualstatement

>>2987380
no, it moves at a constant speed, it just takes a longer path through different medium, denser medium have more things in the way that deflect, absorb and re emit the light
the speed of light is a constant EVERYWHERE

>>2986810
People, especially undergrad physics students who should know better, claiming that string theory is stupid when they know nothing about it

>>2987380

No. >>2987405 got it right.
Light always moves at C. The wave might propagate at a different speed depending on the medium, but the photons are always moving at C. (if my terminology is correct)

Popular scientific misconception: friendship is not magic :p

Reading this thread burngs my eye balls half of you don't know shit and the rest just say stupid shit without proving it.....
so i wont say anything.

>>2987399

Indeed, though your example lends itself very easily to D'Alembert-ization.

>>2986825
So then the laws of thermodynamics apply to Earth, motherfucker.
Lrn2premiss

>>2987490
Yes. I agree that I was wrong to say "D'Alembert Solution".

>>2987016
That kind of contradicts itself, if I may Captain Obvious it up in here.
I'd like to ponder that particular subject more.