Atom Bombs and Dimensional Analysis - Sixty Symbols

[jq747]

That bigass amp meter... now that's what real science is all about ^^

[Harudath]

"This is a thermometer, not an ordinary thermometer that your mother should shove in your ar-" I thought he was going somewhere else at that point..

Still, loved the video

[MrAriba69]

"the exact power of the bomb was a closely guarded sceret." tut tut tut

[motionapplied]

/watch?v=v_M_iItYidQ

[1pnoe]

[great video]

[warnford]

These videos are Great ! and the comments ! [ honestly men can be bit**es ]

[tragik911]

[inverse square law]

[DrRapistaa]

L. Sedov first estimated the yield of the nuclear bomb

msowww.anu.edu.au/~geoff/AFD/S­edov.pdf

[TakronRust]

If I'm not mistaken though about Amps, they are not a basic unit, because they can be broken down into coulombs and time.

[UmlautBanana]

@TakronRust No, they're one of the seven basic SI units. Coulombs, while they cannot be broken down, are not officially SI.

[jimo1150]

Armpit or ELSE WHERE!!

[Apjooz]

Seems to me the guy just did some extrapolation.

[jogurt01122]

0:06 a face

[eoghanpierce1]

@jogurt01122

creepy



[QuantumDisciple7]

I just liked the video before I even watched it, because I know I won't be disappointed in the next 5 min.

[huntingvuk]

very cool,thank you

[disbandedNinja]

slap-dash. another word added to my vocabulary that will make others confused.

[pivotcrave]

or other places huh...

lol

[gomunkul]

@kristijan0kroflin "but it does matter that you limit yourself to a certain one", why does it matter?

In problems where I use dimensional analysis, most often I use the same dimensions but sometimes I use somewhat different ones when it makes the results more intuitive or more simple. I don't blindly limit myself to a set of dimensions. As to Prof. Walter Lewin, he is most certainly right that we all should use right-handed coordinate systems but again, nature is independent from coordinates :)

[musselma]

Is Dimensional Analysis necessary here? It seems like he had the units and solved an equation. If I see turbulent flow in a pipe, I can assume a Reynolds number and solve for the flow rate--but I'm not using DA explicitly. Is that a fair analogy?

[gomunkul]

@musselma you are correct, the guy who calculated the force of the a-bomb didn't used dimensional analysis EXPLICITLY. BUT the guy who created the EQUATION that was used to calculate the force, was derived using PURE dimensional analysis.

[ifsey]

But current is Q/t, and so charge is more fundamental... But I would never dare argue with Prof. Bowley...

[gomunkul]

@ifsey you will find your answerd if you read about dimensional analysis.

it doesn't matter what DIMENSIONS you use, nothing fundamental in any of them. what you are talking about are UNITS. when you talking about dimensions one can chose Force instead of Mass and Velocity instead of Length. the dimensions must be independent, that's all and you will get the same answer.

[elkrobber]

why does he use current not charge? surely current is not a base unit

[gomunkul]

@elkrobber he answered you question in the video. it doesn't matter what the units are, only the DIMENSIONS matter. so it doesn't really matter if you use charge or current, also you can use Force and not Mass etc.

read about it...

[Accursed2552]

it's as big as a barn

[nicepianoplayer]

Amper isn't a basic dimension.

Coulomb is...

[JuanchoMan]

@kristijanadrian ಠ_ಠ

[JuanchoMan]

shhh dont tell anyone its a "sceret"!

[nelombra]

All those abstract concepts in the brackets do not exist necessarily per se. They actually are relative to some measuring instrument used at a given place and time by someone. Einstein anyone?

[jjovereats]

... I think he showed that 'military intelligence' was a bit of an oxymoron.

End of this video

[rockthecityatnight]

Math is amazing.

[TriKri]

Why do you have the name Sixty Symbols?

[MrOldprof]

@TriKri

Because when we started to do the videos, the aim was to do sixty of them; they were a success so we decided to sixty more; and now Brady wants us to do more, so long as the funding is there. It's like a treadmill. I would have preferred Sixty Sexy Symbols.

[optsyn]

nice. i remember doing this problem in applied mathematics. awesome problem.

[lionchamp29]

odd how countries use these bombs on themselves?

[MrBeautifulba1]

I'm a fucking idiot.

[rampike74]

Oxi _moron_? ;)

[Mojosbigstick]

Thank you! I've often felt that units are useful tools, but basically human constructs, and therefore not fundamentally real. It's nice to know there's a way to work without them.

[red00devil]

shouldn't charge be used instead of current, since current itself is a combination of charge and another abstract quantity:time ?

[plmnbvcxz1234567890]

@red00devil yeah, this guy said a lot of incorrect things. Mass ain't measured in pounds, temperature is a combination of length, time, and mass... he says "naught" instead of "zero", he's all wrong

[puncheex]

@kristijanadrian: Well, that sure lets the humanities off the hook, doesn't it? Do you suppose chemists are included, or not?

[puncheex]

It seems to me that there has to be a basic dimensional unit for luminance, which SI unit is the candela, as well as the others: length, time, mass, temperature, current (or charge). An amount variable is also sometimes mentioned whose unit is the mole, but it is also often treated, like angle, as dimensionless.

[Acrimonator]

@kristijanadrian Come back when you'll have something else that insult and you'll be able to make some sense, because actually you're just blowing air... Pityful troll...

[Acrimonator]

@kristijanadrian "their children will be held responsible" couldn't have a more judeo-christian reaction... Even if I agree with most of what you said, I couldn't let that gem pass...

[Einstreit]

"The exact power of the bomb was a closely guarded SCERET"

w00t typo

[MillyVanillification]

Brilliant

[GRAHAMAUS]

@kristijanadrian What utter nonsense.

[motionapplied]

@GRAHAMAUS ...types the one who lives in a society that is only possible because it sucks and sucked (en . wikipedia . org / wiki / British_Empire) out other countries and who wanted to collaborate with the national socialists against the russian partisans. you know that your relatives neither are safe in the uk nor when they're outside the uk - mi cemo vas odgojit.

[motionapplied]

@GRAHAMAUS "Ooh, send me to the burn unit."

[8nwidth]

[ ? ]

[MrAsiansunite]

Dear Sixtysymbols, I might be wrong, but isn't this method first introduced by James Maxwell, but not Taylor? No I am not wrong, I know for sure)))

[Shannariano]

I love sixtysymbols! They use metric system!

And here in italy we are forced by university teachers to do maths that involve feet gallons and psi -.-"

[weeryan2008]

@Shannariano Ewwwwww.

[Involtin]

@Shannariano i study aerospace engineering at university of padua in italy and we use metric system

also metric system is the prevalent in europe, and in italy everyone uses it, how can you say someone would teach with the imperial system...

[llVIU]

@Shannariano ahhahahhahaahhahahahahahhahaha­hahah what

[Arwiiss]

@Shannariano It's pretty strange as accepted scientific language uses metric system everywhere and I mean everywhere. Only scientific journals with target audience of non scientists convert metrics into other systems usually leaving metric value in brackets.

[motionapplied]

@Shannariano ...why did YOU use it? "forced"...only weak minds are forced...weak minds that want to "stay in line".

[Shannariano]

@motionapplied I used it because the question was something like "here are the datas in PSI, farenheit and gallons per hour, give me the result in iardes" about the optimal length of a tube under a frozen lake.

I'm not saying that I used the datas in the math, but that I had to convert to metric before being able to do the math. same with the results.

[motionapplied]

@Shannariano in maths and the unified description of nature (=physics) formal diversity has nothing lost - since it's diverting from the diversity of degrees of the scale dimension, from the diversity of angles as well as from the diversity of distances of observation. don't you have an app for converting units? there's convertall for ubuntu, there are various for android (like for example convertpad - but i didn't test all available yet)...

[motionapplied]

@Shannariano ...you know why some tried to keep the bible being written only in latin? for the same reason why some still try to keep a diversity of unit-systems as well as they increase the "technical terminology" day by day. still form rules over content.

[motionapplied]

@Shannariano ...you chose berlusconi as your chief administrator and can't get rid of the mafia (the result of your system which produces bums and hopes that there are enough idiots that let themselves make to bums - if someone thinks one sees that it's better to be a member of the mafia (or church) than to be a bum) by giving their members acceptable life-alternatives.

[Shannariano]

@motionapplied how does that actually matter with my comment about metric system?

[motionapplied]

@Shannariano ...not long ago italian scientists claimed to have demonstrated cold fusion. everything you do is bluffing and hiding your bluff by deviating from the norm

of notation. the catholic church did that by keeping the bible in latin so that the citizens couldn't understand that they've been fooled with nothingness. keep the weird things in your art (which now got shallow by becoming "internationalized").

[pythor2]

@Shannariano Yeah we're forced to as well, but it's not because the professors like it either.

[huntmatuk]

When making these videos, it would be good to getthe names of the people doing them as it is fun to look at what they do for thie research.

[puncheex]

The point in dimensional analysis is that if someone presents you with an equation representing some physical computation that you are unfamiliar with, a quick dimensional check can verify if the equation makes sense. Dimensional truth of an equation is a necessary, but not sufficient condition for the equation to be correct.

[puncheex]

The professor's point here is that the gentleman in England didn't need to know the size of the pressure wave or other esoteric specifics of the blast; he simply needed to scale up from known smaller blasts to this one in order to estimate the yield. This is because the dimensions in the equation cancel out, allowing a simple linear scaling to perform where a person faced with just the size of the blast wave would need all sorts of specific data from the blast to determine he yield.

[1971ojoalparche1971]

If my mother had used a thermometer like that in my elsewhere, I'd never ever celebrate Mother's Day, and there's nothing abstract about that.

[nolsmtm]

so if those were the fundamental units, what about angles? are they a fundamental unit as they can't be broken down into anything simpler? they are just measured in degrees.

[puncheex]

@nolsmtm: Angular measurement is in terms of [L/L] or are themselves dimensionless (for the purposes of dimensional analysis). Same goes for solid angles. The derived SI unit for angles is the radian and steradian.

[nolsmtm]

@puncheex thanks for helping me out there when wikipedia could not:)

[drinksupreme]

in your armpit... or elswhere... :)

[Richy15251]

Amperes aren't a fundamental unit, coulombs are :P Amperes are measured in coulombs per second (C/s)

Strange, We use the Standard System of Units in Canada, time uses lower t [t] and temperature uses big T [T]

[yondaime500]

@Richy15251 Actually that's a common misconception (at least I think it's common, I used to think that too). Ampere is the fundamental unit. The definition of Coulomb is: "One coulomb is the amount of electric charge transported in one second by a steady current of one ampere." It's just that we usually learn about coulombs first at school, then we learn that ampere is coulomb per second.

[Richy15251]

@yondaime500 oh that's pretty cool, and it makes no sense XD I dunno, I guess there must be some reason for it. It's just that a coulomb is a fundamental quantity, a particle can have a force charge and a 'mass charge' it just seems natural that both of them would be considered fundamental unit. :)

[yondaime500]

@Richy15251 It's really odd, indeed. I was checking the articles on wikipedia, and it turns out that ampere's law doesn't even mention coulomb, and vice-versa. But ampere's law was published 43 years after coulomb's. The definition of an ampere is based on some complicated electromagnetism equations that I didn't bother trying to understand, but it seems that electric charge didn't matter at all.

[puncheex]

@Richy15251: Either one could be, actually. Current is charge/time, and charge is current.time, so one is basic and one derived, but the Bible doesn't tell us which one was god's favorite.

[DoubleDoubtable]

Am I the only one who saw a face at 0:07?

[DarkKnightBob1o1]

@DoubleDoubtable 9/11 was an insect job

[nab3042]

creepy

[4081kieran]

could somone explane this too me. im intrested but i dont understand how do you measure somthing without useing any kind of measurement.

i would apreciate it if somone could explane in a simple way. I got an A in physics GCSE but thats as far as it goes

[LouSaydus]

They aren't measuring things without a measurement, they are measuring it without units. It's simple really, think about it this way. You are one "unit" tall, the table next to you is half your height so it's .5 "units" tall. Lets say in meters (just another type of unit) you're 2 meters tall, that means your table is 1 meter tall, as one "unit" is equal to 2 meters. Hope that helps clear it up some.

[oOoxelAoOo]

Dimensional analysis is an incredibly useful tool. I've used it in fluid dynamics to determine the flow rate you'd need to use in scale modelling.

[sidewaysfcs0718]

the video has nothing to do with extra dimensions u retard.

[rerevisionist]

@sidewaysfcs0718 don't know if you mean oxo or me.

I meant the article must have been checked - it's a pretence with a view to pretending the explosion was genuine. Just look at the photo. NB one of the 'h bomb' photos has a similar hard edge for a bit - they seem to have dropped that fetaure later

[zero1gmv]

5/5 ":P

[Thepunishingguy]

0:07

LoL,my stupid imaginative mind is telling me that i can see a face in the mushroom cloud...

[whlzdenis]

same here :)

and it does look like a face :)

[shine0125]

so can i freaky

[meefefe]

Holy shit lol. That does look pretty damn freaky.

[Thepunishingguy]

lol,Hail Satan

[pyromaniac1223]

looks like a skull lol

[melbn]

thermo 4 ur arm pit or elsewhere lol

[shine0125]

i was thinking that

[timerider4]

I still don't really understand what he means by "abstract" with no unit attached. How could he find the size of the bomb without using units of measurement?

[jestertru]

The basic idea is that the specific units of measure aren't as important as the mathematical relationships between the variables. The result is that there are only 5 fundamental variables for any physical law (at least in Newtonian mechanics) and everything else is math. This allows similar phenomena to be compared by simple scaling relationships (which is how the bomb size was estimated from declassified data in the magazine photo). There really is no such thing as secrets with physics.

[emdog2564]

perfectly worded.

[1ppychix]

Hey did anyone else see the face in the cloud at 7 seconds spoooookkkkyyy

[AudibleAura]

that was the god of fire =)>

[XManXHunterX]

@1ppychix I SEE IT CREEPY ...REALLY CREPPY

[jnoir87]

Been learning all about the Buckingham Pi theroem today, hard to get your head round, but interesting all the same!

[HerrCaZini]

at 0:34

[sixtysymbols]

@HerrCaZini : you've ruined my day

[HerrCaZini]

ow sorrrryyyy only wanted to help

[MrJoviun]

@HerrCaZini What?

[Kesh789]

@HerrCaZini what about it

[Imac717]

@Kesh789 look how they spelled secret...

[getonitman20]

great video. Unusual camera work but works perfectly always following the attention.

I really like these videos!

[Artificialkel]

My name is Kelvin....lol....for real xD

[ObzidianStar]

Physicists are not hypocrites...ha! love this video...love it.

[pin3appel]

there's a pretty interesting video on dimensional analysis by MIT

not saying that this one wasn't interesting too :D

[Kev888]

Military intelligence, two words combined that can't make sense!

-Megadeth

[LooseLatitude]

"The nation that will insist upon drawing a broad line of demarcation between the fighting man and the thinking man is liable to find its fighting done by fools and its thinking by cowards"

-General Sir William Butler

[laputahayom]

good quote

[jpsalsman]

Well, I'm not sure this is the best example for dimensional analysis, given that the time and blast radius were in fact measured. The relationship, e.g., between acceleration and velocity might be better to state in the purely abstract.

[lucas123kowe]

at 2:40 isnt that a newtonmeter? ie measures force

ie measures weight

ie you cant derive the mass from it without knowing the force due to gravity?

Physicists should have an empirical manner.

Meh at least theres some decent science videos on youtube well done

[nolongerlong]

well, technically it's a newtonmeter, - so is any set of scales - but since g is a very well defined constant (9.80665) the mass of any object on (or reasonably near) the surface of the earth can be inferred from the force due to gravity, using F=ma.

I suppose another way to measure something's mass would be to push it with a known amount of force and measure its acceleration, but it'd be quite difficult to do in such a way that friction is negligible.

[samipso]

Interesting video.

[GrandTheftAuto4Films]

Awesome vid, keep em' coming!

[NAMLegolas]

Wow, Busting like that the US government has to be epic! ^_^

Great video :)

[Chipsonfire]

Engineers also use this technique for fluid analysis.

[Intervene]

Fantastic video. Fascinating stuff.

Thanks.

[CoolMinty]

Fascinating. I especially like the joke at the end ;)

[saemj]

there is no joke at the end.

[carranzapz]

what are u dumb?

[cagedkiller360]

Awesome stuff. I think moles and candelas are also basic quantities.

[nolongerlong]

Well, the 'unitless' names would be something like 'amount of substance' and 'luminous intensity', but yes, there are 7 dimensionally independent basic quantities, which correspond to the 7 SI base units. You can derive any other physical quantity/unit from these 7.

[sixtysymbols]

Timing if this post was pure coincidence by the way... But was fascinated to read that the North Korea test is believed to be 20KT

[DeoMachina]

Or was it? DUN DUN DUUUN

Perhaps you've stumbled upon a new law that can be used to work out when nuclear tests are about to occur.

[MatthewIsAwesomeFTW]

nice