Archived threads in /sci/ - Science & Math - 388. page
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Do schedules and deadlines cuck my natural inclination to feel free or is giving my free time no structure an invitation to be cucked and maniplulated by the modern world?
saged
saged
saged
Any thoughts on Herschel's doodle, /sci/?
Full explanation: https://www.youtube.com/watch?v=vn-0zSuAWpI
tl;dr:
http://www.bradyharanblog.com/blog/2015/7/10/herschels-mysterious-doodle-1
>>7810474
probly nothing
>>7810474
the devils in the details, humorous doodle about the limitations of our senses
He's fucking shit at drawing alright.
Where can I find physics formulas? I'm not studying at an uni, but I'd like to solve things concerning CMB but I don't know where to find them.
just go on wikipedia, type cmb, read the first equation and you're pretty much done. go to MIT and pick up your physics PhD
>>7810375
>I want to solve things concerning CMB
>Where can I find physics formulas?
lmao
>he thinks the problems of physics can be solved just by doing algebra on the equations we have
I got into a conversation with a friend of a friend recently who told me that he took the equations of general relativity and particle physics, set them to zero and tried equating them but he couldn't make the math work out. I had to not call him fucking retarded and I think I deserve compensation.
Can anyone help me in this.
There's some kind of trick that I can't seem to find.
>what is trigonometry
http://www.wolframalpha.com/input/?i=sin%28x%29*cos%28y%29
Back2School with you
>>7810298
That isn't the problem. Computing 10-point dft is time consuming. There's somekind of trick in here
DFT is a linear function, so I would write
[math] \displaystyle \cos \left ( \frac{3 \pi }{5}n \right ) \sin \left ( \frac{4 \pi }{5}n \right )= \frac{1}{2} \left ( \sin \left ( \frac{ \pi }{5}n \right )+ \sin \left ( \frac{7 \pi }{5}n \right ) \right )[/math]
and sum the 10-point DFT for the two sine functions.
I would like to learn more about chemistry in a casual way. What are some good YouTube channels for that?
>>7810166
NurdRage is a chemist that puts out cool and exciting videos, yet still respects the chemistry and will teach it.
Applied Science is another excellent channel, but his videos cover all physical sciences. Just go onto his channel and select the chemistry playlist.
I second this thread
>>7810166
Try watching Breaking Bad you'll be making mad crystal in no time! :^)
Many meat eating animals consume pebbles and rocks to help them break down meat and grind it up for digestion. How come humans don't need to do this?
Since that behavior is now uncommon than not, wouldn't it make more sense to ask why some species DO need to do that?
>>7809772
Because we chew?
Retard
>>7809772
>How come humans don't need to do this?
Because through evolution we have assimilated tens of thousands of different species of microbes that now make up our intestinal fauna and expedite food digestion.
Hello, /sci/!
I'm an undergraduate in computer science (hopefully) going on to graduate study next year. Since my program is research-oriented, and also because I can't always take classes in subjects I'm interested in, I spend a lot of free time trying my hand at traditionally 'hard' problems in order to get practice tackling unanswered questions (or at least questions whose answers haven't yet been proven beyond doubt).
I've recently come up with a fast heuristic (I'm calling it so because I don't yet have the grounds...
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Also, P =? NP general, if that sparks anybody's interest.
To those better versed than I: what is the current state of approximability of graph-related NP-hard problems? I read a paper stating that there's a proven maximum bound on the approximation factor for any maximum clique algorithm of n^(1/3) (unless P = NP), but I'm not sure if there's been any change since that point.
>>7809740
>hard even to approximate in polynomial time
Stop your research immediately before you do something that many more people will regret. The government is not to be trusted in any whit.
>>7809785
I highly doubt anything I do as an undergraduate toying with concepts will result in anything earth-shattering. But I suppose I should thank you for thinking that it might!
Hello /sci/!
I've just now discovered my love for math, and just started to tackle antiderivatives. Please bare in mind that i have no prior knowlage of math exept for the basics. I was hoping you could help me fuel this newly found love. I'm currently stuck with this one, could you help me understand the process and how to reach the result?
>>7809578
we use the legendary plug and chug technique
someone should make a flow chart but in anycase:
1) observe that his is a fraction with a 4th degree polynomial in the denominator. therefore the flowchart say partial fraction that bitch
-(x + 1)/(x^2 + 1) + 1/x + x^(-2)
now we may integrate these 3 components seperately by plug-and-chugging them into our already known antiderivative patterns:
1/x => ln(x)
x^(-2) => -x^(-1)
-(x + 1)/(x^2 + 1) => -ln(x^2+1) + atan(x)
testingczs
[math]x = e^{x}[/math]
[math]\frac{x+1}{x^4 + x^2} = \frac{x}{x^4 + x^2} + \frac{1}{x^4 + x^2} = \frac{1}{x^2(x + 1)} + \frac{1}{x^2(x^2 + 1)} [/math]
Now comes the tricky part.
find A, B such that
[math]
\frac{1}{x^2(x + 1)} = \frac{A}{x^2} + \frac{B}{x+1}
[/math]
Then integrate.
Do the same for the second term.
For an event to occur, in an interval of 28 days, you have a chance of 0 for the first 23 days and then chances [math] p_1, p_2, p_3, p_4, p_5 [/math] (each in [0,1], no correlation between the p_i's) in the remaining 5 days.
You probe this setup at a random day, the particular day you choose is given by a probability P (with [math] \sum_{n=1}^{28} P(n) = 1 [/math]).
What are the chances for the event to occur?
For starters, I think for P(n)==1/28 constant, you get
[math] \dfrac {1} {28} \sum_{n=i}^{5} p_i [/math],
but that's just my intuition.
>>7809341
if the sum of probabilities over 28 days is 1 and the probabilities of the first 23 are 0 then the sum of probabilities over the last 5 days are 1, so the probability of it happening in those days is 1...
Assuming they're equal, each day is 1/5 chance
>>7809341
>What are the chances for the event to occur?
if do not ask about what time interval, since all your problem deals with time intervals, you have no answer to your problem.
>>7809341
>a chance
>the chances
Lrn2probabilly
I'm not a science major or anything, but I've heard that steady-state theory has been coming back in fashion somewhat. Is this true and if so, why?
>>7809264
That seems unlikely. The steady state theory doesn't explain the cosmic microwave background.
http://physicscentral.com/explore/action/femtosecond-hologram.cfm
Some Japanese researchers managed to create real aerial interactive holograms using femtosecond lasers. What are the chances that this technology could be used to create a complete functional Holodeck like that seen in Star Trek?
Here is a picture of how the projection works.
>>7809063
Cant click the link now but isnt this old as fuck? Like at least a year or two. Id say unlikely for a holodeck experience, but give it a few decades and we might see some practical uses in telecommunication
>>7809063
Not a chance. It uses big dangerous lasers that can blind you and literally generate air pollution.
What do you think will happen to humanity when the first working fusion reactors are developed and we become capable of producing infinite clean energy? What will it change about how we operate as a species?
If free market is really true and not just a meme, energy would become extremely cheap and the economy of all places arround the world, specialy that of developing countries, would grow very significantly. However, there would also be unemployment in the sectors of energy, like coal thermeletrics and oil refineries. Middle Eastern countries would be specially upset. Somehow I think that, if this happened, a monopoly would possibly come out of this. And monopolies ain't good. The unemployment itself would be a very hard issue to cope with, it could increase government expenditure...
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>>7809032
This.
Yeah oil is not going away anytime soon kids
>>7809049
ah man, i hope we achieve fusion big time.
Anyone proeficient with fluid dynamics here? Is it possible to determine the diameter of the urethra, based on the speed at which urine is expelled? From this data, can we obtain a rought estimate on girth as well as length of a penis? I was thinking of relating the sound of the urination to force and then size of a penis. Any help in this endeavor will be appreciated.
>>7808799
Idk man. You might have to find a general solution to the Navier-Stokes to figure that out.
>>7808799
You'll need to know if there's any head loss and if any energy is going into shaft work.
>>7808799
>Is it possible to determine the diameter of the urethra, based on the speed at which urine is expelled?
No, because the mass flow rate of urine is something in your control. If you use your pelvic muscles you can pee harder and if you completely relax, the pee will be weak. And because this value is not constant and can vary from person to person, you won't get any good estimates.
Is there anyone here studying science in their own time whilst working a job?
How do you ensure you are getting a thorough education on such a limited time schedule?
I work 8.5 hour days 6 days per-week. I'm trying to give myself an introduction to Chemistry but I feel like I am getting a sub-par education through reading text books at home. It is tough to follow a real curriculum.
Does anybody feel they are doing this effectively and with success?
>>7805461
> 6 days per-week
Fuck man please tell me that this is not a standard and that you just work a really shitty job.
This cannot be real.
>>7805478
Telesales bru :'(
>>7805461
are you doing problems at the end of each chapter or are you just reading the book?
This decides how much you actually learn.
Why is the observable universe a sphere with us at the center?
In theory wouldn't that mean light(photons) is coming towards us from all directions? Pic related
>>7810333
Because we can see (roughly) the same distance in every direction
so it defines a sphere centered at where we observe from (here)
and yes, that does mean light's coming at us from every direction, but that's nothing particularly dazzling
if you look around you in space there's always going to be stars on all sides of you unless you were at the very edge of the universe for some reason
>>7810336
Now what about the microwave radiation background wouldn't that make it look closer to a come due to the fact that we are looking at a single point of origin for said radiation?
>>7810340
The CMB is observed in all directions. Maps you see of it are usually full sky.
