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when it is said that the speed of light is 2.99e8 is there any error or deviation? Does light ever go slightly faster or slower?
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>>8729769
In open, flat space, no.
However, light travels slower through media, i.e. glass and water, because of some weird quantum effects I won't pretend that I understand enough to explain.
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https://www.sciencenews.org/article/speed-light-not-so-constant-after-all
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>>8729769
The definition of the meter is based on the speed of light, so c can't have any error (but the meter itself can). When we talk about the speed of light we usually talk about the speed in vacuum. It can't go faster than that under any circumstance, but it goes slower if it goes through any other medium.
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so electrons, other elementary particles etc. are completely identical from one another right? it is not possible to distinguish an electron from another one positioned somewhere else in space.
does that imply the oxygen molecules i breath in are also everyone else's at the same time?
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>>8729752
In practice, yes, particles are equivalent. But there can be isotopes with more neutrons, or the atoms can be ionized, so not all the oxygen molecules are exactly the same.
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>>8729806
but each variations are all locally identical yes? why is it not possible to assign a "name" to a fundamental particle?
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>>8729817
Because everything is delocalized
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Will the first design have a higher boiling rate, assuming heat properly reaches all the surface area between the fins? Why / why not?
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>>8729631
Jesus christ. Look up the absolute basics of heat transfer before making shitty threads. We're not going to do all of your thinking for you, brainlet.
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>>8729631
What's a boiling rate?
The amount of fluid that is lost to steam per second or the time it takes to heat the fluid to boiling?
You might want to check out old sugar shack boilers, if it's the first one you want.
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>>8729635
I read up on Fourier's law but trying to confirm my understanding.
If it's that easy for you you could take 5 seconds to answer the question. This isn't the arch linux forum.
>>8729640
The former.
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Sup, /sci/? I'd appreciate some advice if you anons would be cool with that.
I'm 22 and I've always had a pretty terrible experience with the public school system-I've struggled with ADHD my entire life- and naturally withdrew from that type of environment and focused on the things that did matter to me.
Those things were video games and music. I've developed a pretty decent ability when it comes to understanding and creating music- It's currently what I'm studying in school-but I've come to a point where I've realized how important it is that I spend my time better than I have been. Through forcing myself to watch and try and understand things like Carl Sagan's series "Cosmos", and reading some of his books(the Demon Haunted World, for example). I've come to realize how amazing and beautiful the world can be through the lens of science. How important it is as a tool to not only understand the world and ourselves, but the choices we make, and the progression of human history. My abilities to perform and understand scientific and mathematical formula would probably be sub-par, but It's important that I do what I can to try and learn as much as I can about this sort of thing.
Where should I start?
What sort of people have influenced you in life?
I'd love to know.
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>>8729385
>implying adhd is a real disease
Check out Jordan Peterson :
https://www.youtube.com/watch?v=LH0FiV3IXYo
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>>8729385
pic unrelated: Just an amazing composer
https://www.youtube.com/watch?v=lQabCdxJ6DM
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>>8729393
I will, but I've certainly been medicated for it my entire life. That I do know is real.
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Hi! I've been meaning to ask, and I think that this board is more related than /wsr/ for this. Anyway. I've been doing my math homework, and I was wondering on how to go about it. I've looked at some tutorials online, but now my problem is that, it seems that almost every example that they give me, they use some trick to solve it.
I know this sounds vague, so allow me to give an example. If i were to solve a function limit question: (lim, t-1) t^3-t/t^2-1. I get that in order to use that specific equation, i need to factorize it, so i'll have: t(t^2-1)/(t^2-1), and you go about solving the thing.
But my problem is with this, how can you know exactly how to manipulate the equation in order to solve the equation, like the guy who was explaining the above equation, knew that he had to use factorization in order to solve the equation, but how? Or when do I need to rationalize a fraction in order to get the right answer? Am I missing the point of math entirely?
I'm sorry if this might be considered inappropriate for the board, I just feel like the fact of not knowing what to do or where to start, gives me more frustration and headaches, and I need help. PLEASE.
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I guess basically what I'm asking is, how do I get math?
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I think you need to practice your algebra
factoring polynomials allows you to substitute a limit so that the denominator doesn't result to zero (can't divide by zero). doing that enables you to find where the limit exists
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>>8729386
I know that, but how do I know which method to use when? Are you saying that it will come naturally as I just plow through different worksheets?
Anonymous
the point of password salt? 2017-03-07 08:03:46 Post No.8729305
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the point of password salt? 2017-03-07 08:03:46 Post No.8729305
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the point of password salt?
Anonymous
2017-03-07 08:03:46
Post No. 8729305
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I understand that salt makes it harder to use rainbow table to find password given a table of hashed password.
But since you already have a table of hashed password, meaning the server is already compromised, why can't you have each user's salt as well?
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>>8729305
You typically do have the salts in the password file, but even knowing the salt doesn't mean you know the hash. You have to run the hash function for each line, because matched hashes don't correspond to matched passwords if they're salted.
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If 1000 people in your database used 'password' as their password, an attacker would crack all of them by cracking one. Salts prevent this.
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Hey /sci/, I'm looking for inspiration for a sci-fi project.
I read once that a quantum computer makes operations with less steps than a normal computer, because of a superposition. I'm not saying that I understood all this math, since I'm still a brainlet, but I understand that it won't load my pornhub video faster, the differences between quantum computers and normal computers are just "math is faster in quantum!" and "we can decrypt faster in quantum!".
But does this applies to simulations as well? I mean, if we started a simulation of the universe in a quantum computer with a lot of memory to be stored, top quality equipaments so there wouldn't be a interference or break, would it be possible to recreate every single step of the universe in a computer? Or even the other paths that it could have followed?
Of course, if something I typed was wrong, please correct it. I may mention you, Anon, in the credits!
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Bump
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God
Someone
Please
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>>8729290
http://www.smbc-comics.com/comic/the-talk-3
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>what're /sci/ approved maths books/textbooks?
>is sleeping 4 hours daily doable?
>how i know that i'm fucking brainlet and cahds/peers are far better than me for true?
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http://4chan-science.wikia.com/wiki//sci/_Wiki
Speaking from experience, 4 hours a day is doable but expect to be lethargic.
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>>8729266
sleeping 4 hours a day really isn't doable unless you're a genetic anomaly.
I personally can't do math for shit without a solid 8hrs. I get 4 hours one day, I can struggle through, but by the second day, I'm pretty much useless until I go back to bed.
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>>8729266
>>how i know that i'm fucking brainlet and cahds/peers are far better than me for true?
Read up on any famous mathematician's accomplishments.
Anonymous
Is this scientifically sound? 2017-03-07 06:41:16 Post No.8729141
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Is this scientifically sound? 2017-03-07 06:41:16 Post No.8729141
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Is this scientifically sound?
Anonymous
2017-03-07 06:41:16
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http://www.orionsarm.com/eg-article/56d428e2e775d
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Introduction
A Programmable Quantum-Dot Array (PQDA) is an arrangement of variable quantum dots 1 that are incorporated into the surfaces of electrically or photonically conductive nanostructured composite films and nanofibers2.
Background
Quantum dots are three dimensional nano-scale structures in which charge carriers (electrons or electron holes) are quantum confined, forming 'artificial atoms' (a-atoms). The number of charge carriers that are confined in each quantum dot can be adjusted in real-time by electrical or photonic signals, ranging from one up into the thousands. The size, shape, and symmetry of these a-atoms can also be tuned to some extent.
Q-dot based a-atoms are significantly larger than the atoms of the classical chemical elements, which means that although they may have the same number of electrons as an atom of a particular element, an a-atom of that element has properties that are orders of magnitude weaker, or significantly different, than the natural version and thus they are not equivalent. In contrast to classical atoms, a-atoms do not have an atomic nucleus, which means that a-atoms (ignoring the substrate they are confined in) have a low mass that is dependent on the number of charge carriers that are present (electrons have a mass of approx. 1/1836th that of protons).
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Despite this, quantum dots have been found to have a number of useful applications, demonstrating optical, electrical, and electromagnetic behaviors significantly different from larger particles. While early quantum dots had to be created with a particular desired property 'locked in', modern versions can change their structures, and therefore properties, as desired and in fractions of a second. Arranged together in large numbers, they form a surface whose every point can emit or absorb light, become semi or superconducting, or generate low power magnetic fields as desired and in variable arrangements that can employ as much or as little of the array as desired.
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Modes and Applications
PQDAs are primarily laid down as films, layers, or ribbons on or within a variety of substrates, such as Ultimate Muscle fibers, utility fog, utility sand, MPTC and BAESFTLA structures, and VIMs. Ribbons and nanofibers are also woven (similarly to woven graphene) into bulk solids.
Because its electrical, magnetic, and optical properties can be adjusted in real time at a level of resolution from individual quantum dots to the sum total, at any given moment a PQDA can function as anything from computronium (analog, digital, and quantum), to photovoltaics, to an optical or radar phased array, to a thermal or optical camera, to a low power electromagnet, to a simple mirror. Or different sections of an array may be set to run different functions in parallel, providing multiple abilities simultaneously.
Whether operating as standalone devices or in combination with other technologies, this flexibility has led to a number of PQDA-based applications. Some particularly notable examples include:
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>ph.d. in shitposting
>meme engineer
>$300k starting
Give me one good reason you aren't majoring in memetics.
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>>8729129
wewlad
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>>8729129
> paying dollar to major in memes when you can get practical experience on 4chan
pffft, employers are going to toss your resume out the window kid
t. shitposter pro
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>>8729129
I'm majoring in remote control cars instead
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How do these things work?
How do They detect that someone is in the room?
How do Light detectors work?
I don't care about circuits or what they do once they detect something i'm talking about the very tiny part of it that detects light/something, how does that happen? A chemical reaction? Something with magnetic fields?
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>>8728862
>i'm talking about the very tiny part of it that detects light/something
Nowadays it's mostly CCDs. Something with semi-conductors and band-gaps.
Earlier the photoelectric effect was used (and amplifiers).
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>>8728877
Thanks Holy Kek.
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>>8728862
They use passive infra red sensors and algorithms that look for a fast changing value. Any warm body gives off IR. The sensor is a phototransistor like what picks up a TV remote but a lot more sensitive.
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I'm a brainlet who's shit at physics, and I wanted to know how much recoil would be produced by such a device
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>>8728857
GAS THE BRAINLETS
IQ WAR NOW
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>>8728858
>GAUSS THE BRAINLETS
FTFY
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>>8728857
F12=-F21
So just as hard as a normal rifle
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So the theory that we live in a simulated reality is becoming more and more popular, which is good because it can actually be tested; heres how.
If we eventually reach a technological level at which we can ourselves simulate realities, we could do so and thus create incredible information density, as the supercomputer rendering our reality now has to render our reality and another artificial reality. Thus if we live in a simulation we would crash it, but if we dont well know we still dont have a purpose in life.
Yay.
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Eventually we'll harness the power of this universe to simulate another universe. This one should have just enough computational power to simulate a universe of equal measure. Then in that universe we will simulate another.
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>>8728949
Do you feel it? Do you feel that I can see your soul? Do you feel it? Do you feel the pain in my heart~
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>>8728833
>Thus if we live in a simulation we would crash it,
Because you definitely can't run a virtual machine hypervisor in a virtual system with technologies we already have for simulating things.
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What sort of degree do I need to get into this.
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>>8728657
Illumenatty-lite
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Youre not down to join the Meme Warfare Center
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Mathematics and Computer Science. Learn about Combinatorial Optimization, Dynamic Systems, Control Theory, statistics, and etc.
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>make repository of plant biodiversity to protect against climate change
>build it in the middle of a melting ice cap
???
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>>8728598
oy vey
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>>8728598
I'd say it floats.
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>>8728598
It's to protect them against whatever, not just global warming, so it's a decent position. Also Svalbard isn't an ice cap.