Earthquakes, Circles and Spheres - Numberphile
ฝัง
- เผยแพร่เมื่อ 26 ก.ย. 2024
- Tadashi is back with a discussion of how we know where earthquakes occur. A second video is at: • Balls and Cones - Numb...
More links & stuff in full description below ↓↓↓
More Tadashi Tokieda at: bit.ly/tadashi_...
Podcasts
HELLO INTERNET
www.hellointern...
UNMADE PODCAST
www.unmade.fm
Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): bit.ly/MSRINumb...
We are also supported by Science Sandbox, a Simons Foundation initiative dedicated to engaging everyone with the process of science. www.simonsfoun...
And support from Math For America - www.mathforame...
NUMBERPHILE
Website: www.numberphile...
Numberphile on Facebook: / numberphile
Numberphile tweets: / numberphile
Subscribe: bit.ly/Numberph...
Videos by Brady Haran
Art and animation in this video by Pete McPartlan
Archive footage courtesy of the AP Archive.
www.aparchive.com/
Patreon: / numberphile
Numberphile T-Shirts: teespring.com/...
Brady's videos subreddit: / bradyharan
Brady's latest videos across all channels: www.bradyharanb...
Sign up for (occasional) emails: eepurl.com/YdjL9
A second video is at: th-cam.com/video/lubGnk0UZt0/w-d-xo.html
The new Objectivity video out today is also worth a look: th-cam.com/video/Sfyd-0tXArc/w-d-xo.html
This video language is set to german so we can't have right automatic subtitles :/
Awesomeness
Numberphile Is this how GPS triangulation works?
The question is why would I NOT want to check out the other video.
@Numberphile - Could you please tell me of anything in reality that is 2 dimensional?
Professor Tadashi should have his own channel, he explains things so well !
He has his own playlist here on Numberphile... bit.ly/tadashi_vids
And that voice! He sounds like the universe explaining itself.
@@numberphile ok I’ve watched them all. So now make more!!
He's well-spoken.
Legitimately the best maths teacher I've ever witnessed.
I'm a simple man. I see a Tadashi video, I click on it.
Actually, I'm a complicated man. I have thoughts, feelings, and ideas.
Lol this meme.
Heavyboxes DIY Master why is your profile pic just your ir someone else's chin?
alien the harold ... It's me. I just wanted to make it different.
Heavyboxes DIY Master its weel spooky i can not know i can handle it
None of us are just "one dimensional" like that! XD
Foolish seismologist: "The earthquake originated from about 30km below the surface."
Enlightened pure mathematician: "Or 30km above the surface."
How is that "pure" mathematic when it doesnt account for the fact that not every output is right,
that only heights below surface are the answere.
It could as well be:
Artist: Thats a Line.
Mathematican: No thats a triangle with two angles of 0° and one 180° angle.
Japan actually has had two earthquakes with an epicenter above the surface. However, the reason is not really funny.
The epicenter is always at the surface. It's the projection of the center onto the surface.
Yeah the US used seismometers, and still does, to detect the hypocenter of atmospheric NUDETs. That job is where I learned my seismology.
projection of the hypocenter*
MY BOI TADASHI IS BACK
He need to come back again
I would love to ask Professor Tadashi if he ever considered writing a book about mathematics and physics of our daily lives. I see that he clearly is one of the greatest science communicators of our time (maybe beyond that) and getting to know a little more on his personnal experiences and philosophy towards education, knowledge and such would be a treat. Of course, I hope the partnership with this channel will go on forever!
P.S. Congratulations to the animation/edition guys. Superb job making an already didactic explanation even more understandable.
What would you want him to communicate? I think his genius is in how he speaks which you wouldn't get from a book.
@@QuasiELVIS what do you mean "how he speaks"? I'm sure it isn't the accent that delivers the point
@@Kokurorokuko he's just funny.
@@QuasiELVIS no only, he delivers information in a very approachable way
@@Kokurorokuko Maybe the pacing?
Good job to the animator on this video! Wow!
Kelvin Lee i know i could watch a show with this style of animation.
It's funny that the p in p-wave stands for both "primary" and "pressure", while the s in s-wave stands for both "secondary" and "shear".
The two polarization components of electromagnetic waves are termed p and s as well. In that case however, p means "parallel" (same in German), while s is German for "senkrecht" (since "perpendicular" also starts with p).
Thanks for the great video, btw!
Tadashi always amazes me.
Us too!
I actually observed this property of three intersecting circles and tried to proof it myself, and failed. Tadashi's explanation just blew my mind! I always loved space with different dimensions, and this video encapsulates my feeling.
I dare say if your epicenter is above ground you shouldn't calculate but run for the nearest fallout shelter.
Also your distance measurement is all wrong because waves travelling through the air and through the earth have different shapes and speeds.
*Center. The epicenter is always at the surface, because it's the projection of the earthquake's center onto the surface.
Hypocenter is the word you are looking for, and yes its also used for atmospheric nuclear detonations.
@@uku4171 I think that for an atmospheric nuclear detonation, the epiccenter is the point on the earth's surface closest to the hypocenter(the center of the detonation). So in this case its above.
"Usually we don't get earthquakes from above" he said very matter-of-factly.
I love his voice. It's very soothing. No morning classes from this guy.
Zilch is a rigorous mathematical term.
Really now?
Miles Quickster r/woooosh
WTH...
Miles Quickster I believe he meant to provide sound for the following situation:
------The Joke---->
*WHOOOSH*
-----Your head-----
Oh. They think I'm serious 😒
Great as always, but I really enjoyed the low-tec visuals!
stlCkofdOom they are called sweed
Really? I thought they were some of the least helpful visual aids I've ever seen, and I already had some knowledge of the stuff being discussed.
The epicenter is, by definition, always on the surface (of the earth). The point below the surface, where the earthquake happens, is called hypocenter.
no but, it is up above ground, in the air.
But if they are above and below the center respectively, where is the center?
I love this video, I studied Surveying in college, and this theorem is right my alley. GPS positioning works on the same basis: you have multiple spheres, each emanating from the one of the GPS satellites, each meeting you GPS receiver's antenna. We can, generally speaking, determine the time it takes for each of them to reach you. With the first sphere, we can place you somewhere in space, on the surface of that sphere. When we add a second sphere, the two intersect to form a circle in space where you might be. Add a third sphere intersecting, and now we have you on either of two points. And just as we don't generally get earthquakes from above, only in exceptionally rare cases are we going to be way out in space. Instead, we can intuit that we are in fact at the one point of the intersection of three spheres... that intersects with a fourth spheroid, namely the earth!
Now, since there are lots of variables involved with the measuring the time is takes for each of those radio signals (spheres) to reach you, we can use the redundant data from the spheres of additional GPS satellites to refine our calculated position.
So too, 4 or 5 or more seismometers are used to pin point the epicenter of an earthquake!
I'm a simple man. I see a Tadashi video, I click on it.
Actually, I'm a complicated man. I have thoughts, feelings, and ideas.
And when I see a Tadashi video, I click on it.
small error in terminology: epicenter refers to the point on the earth's surface directly above the source of the earthquake, itself called the hypocenter.
so if a line is constructed between the 2 meeting points of the spheres, the bottom point will be the hypocenter and the point at which the line intersects the surface of the earth will be the epicenter.
edit: more trivia: for mid-air explosions, it's the opposite; hypocenter on surface, epicenter is explosion source. the math works out the same except sometimes instead of counting the seconds between the flash and the rumble, you start counting when you go blind and stop counting when your organs rupture. or you don't have time to count.
You can also just call it the center or focus, hypocenter is an unnecessary backformation.
hypocenter is nicer because any nuclear scientist or geologists will know immediately what you mean. If you say focus or center, it could be anything.
r77xxl thanks! This is exactly the sort of semantic trivia that I love. Will definitely use.
I'm pretty sure that's what he's explaining at the very end
The hypocenter is at the intersection of the spheres, but the epicenter is at the intersection of the chords of the circles, so I’m not sure he’s as off as all that.
Now if i had teachers like Tadashi i might actually have learned something in school lol
Yes, this guy intermediately impressed me as very clear.
was that a yoke m8?
no you would not, dont blame your/your parents incompetence on teachers
Cypherous Blaming your teachers doesn't solve the problem,you ever heard of self-learning?
Self learning the age before technology when you had no means of long distance transportation, back then all we really had were schools and the library, but without any kind of "reference" how would i have even been aware that something was seriously wrong, i mean we're not talking recent times here we're talking 2 decades :P
I live in northern California, near the Hayward Fault. Before that, I lived closer to the San Andreas Fault. And in my experience living in earthquake zones, the P-wave is more up/down and the S-wave is more side/side. Tadashi's illustration makes sense, but I have a theory that the reason it's reversed in the illustration is because it fails to take depth into account. The closer to the epicenter you are, the more you feel the waves coming from below you, the more vertical the P-wave will be, and the more up/down motion it will cause.
I would love to have a lecturer who teaches like professor Tadashi. He is excellent at explaining things
'Usually we don't have earth quakes from above', this made my day :)
this guy is my new favorite on Numberphile
There is a ban on athmospheric atomic bomb tests, so if we assume everyone holds the ban the "quake" must have been underground. Seismographs are easy way to detect atomic (or hydrogenic) bomb tests.
As a geologist this is a wonderful explanation. Love it!
Tadashi-sensei is a great explainer. I could never interpret the difference between pressure waves and shear waves.
Lovely animation, it's great to see this channel improving.
one of the best numberphile videos of all time
That idea of measuring the seconds between two waves or between the lightning and the thunder actually has an interesting application in military combat scenarios.
Due to the fact that most sniper rifle bullets move at well in excess of the speed of sound, you actually use the elapsed time between the supersonic crack of a bullet going past you and the thump of the rifle that fired it going off in the distance, and you can actually estimate the distance that the enemy sniper fired at you from. If you take that most rounds that might be fired at you from long range have a muzzle velocity of between 700 and 800 m/s (we'll call it at the average of 750 m/s), and the speed of sound is about 343 m/s, and then you account for all the things that slow a bullet down after it leaves the muzzle, like air resistance, wind, gravity, etc., then you get a delay of somewhere just over 300 meters for every second between the crack of the bullet whizzing past you and the thump of the rifle going off. When you hear a crack, start counting (as you take cover, of course). 2 second elapsed means the enemy sniper is approximately just beyond 600 meters from your position.
Snipers call the technique "Crack-Thump", and it's extremely useful in helping to find the enemy sniper who's shooting at you so you can engage him and win the fight. Most of you will never need that information, but for what it's worth there's actually a lot of really cool applications for math, mainly for geometry and trigonometry, in long range shooting.
The explanations of Tadashi are always so amazing. Great video!
Every single school and university should have someone like professor Tadashi
I'm a 42 year old man and I just love the playfulness of Tadashi's videos. There can never be too many Tadashi videos so make more :-)
His drawing with him and his baby is absolutely adorable.
he draws with words. Its so clear
I love the recent increase in Numberphile's animation production value! 💕👌
Both the math and the earthquake calculation were stunning!!
I really enjoyed this video and the creative visualisations too.
understood this *completely*
this man is a wonderful, wonderful teacher. Tadashi.
Pretty sure I heard a Wilhelm scream.
Great video and easy to follow.
The animations are superb. The tectonic plate spazzing around had me laughing out loud.
I love how professor Tadashi explain things and the animations were awesome
This is what I would call double 'joy of learning' moments
Visuals of this make me feel like I am back in Beakman's world, basically, I loved them!
Ah! The animations!
Wow. This is one of my favorite Numberphile videos. I am getting the tingles, because the connections he is able to make and explain so clearly are elegant and insightful
15:30 "-Of course, the epicenter could have been above as well.
-Usually, we don't get an earthquake from above" 😂
I know it's been over a year since this was made but this professor is so much fun. He's very clear and easy to understand.
This was the very first time watching one of your videos. I've been subscribed to it for a little while, but never got around to it. Absolutely fascinating.
This circle method of triangulation gives you the distance to the hypocenter (or focus) of the earthquake. The epicenter would be where all three circles intersect.
Tadashi is so gifted, they can teach me things I don't understand and, (as is the case today), keep me entertained and interested even when explaining something I already understand.
I first learned about this kind of spherical triangulation while playing Eve online.
Was really helpful in visualizing the scanning probes functionality.
animations are looking gorgeous on this one
Just experienced an earthquake and used his method to check how far the earthquake was, and what do u know, it was spot on 😂
Tadashi is straight-up my favorite Numberphile guest. He always brings something interesting to the table. I wish he was one of the "regulars".
Nice. That gives both the epicenter and focus of a quake.
aww, we have baby Tadashi now
will this channel still be around when he/she is able to grasp these ideas..
Earthquake so strong that it makes Japanese women scream like Wilhelm..
Great video, I accept to wait for the next video that shows that we can reject the point from above using 4-dimensional spheres.
As described in the video, 3 spheres intersecting forms a singular line of contact. To determine a singular *point*, you just need to use the intersection of a 4th sphere across that line. No 4th dimension is necessary.
I have learned SO much about earthquakes, thank you!
I love his illustrations and animations. I think I say that on every video you put out with him in it.
This was so beautifully executed. His teaching method is so clear, so *graspable*, that I sincerely just want to sit at his feet for a few years and take it all in.
Tadashi reminds me of Feynman and some old infamous german orator...He explains things in a way that makes them sooooo obvious and yet 5 minutes later you are astounded that you could think that way.
Excellent demonstration Professor!
I couldn't stop laughing at the spasmodic ring of fire
"it's actually a whole sort of circle thing with the ground underneath"
Best description of earth ever
Tadashi is the best guest star of Numberphile!
Really lovely animation, and a very nice explanation for a Californian who should have known this by now.
Love the new visualization style!
Man, the animation here is so brilliant. I'm always impressed by the animation for the Tadashi videos. Keep up the great work!!
The animations in this one were fantastic
i believe this is the same principle the GNSS system uses to calculate our position on earth's surface. this example with earthquakes was fascinating though. You're wonderful professor Tadashi!!!
This one has great animations. Well done!
The animations are amazing. Just add perfectly to the great content.
The Background Presentation is simple and nice
I thought he was going to address how GPS does essentially the same thing.
Though they actually use four spheres so they can calculate the receivers’ position in time as well (which is needed to accurately locate it).
Very cool though! I’ve never experienced an earthquake but if I do I hope I remember to count!
Currently living in Japan, this was quite interesting!😊
Tadashi is always great
Love the editing and visuals 😍😍 Thank you xoxo
Thanks for an excellent presentation.
Tadashi is my favorite!
I love Tadashi's explanations
this guy is a gift.. Thank you
The animator behind these videos is also brilliant. Your hard work is much appreciated!
Dr Tokieda is such an amazing explainer. I was going to say, "like a Richard Feynman of mathematics," but then Tadashi is sort of a physicist too. Maybe that's what gave them such intuitive descriptions for math!
Beautiful. And very well explained.
"So what does this have to do with this theorem?...everything has to do with this theorem."
-sensei tadashi
Love the graphics in this one.
Beautiful animations and stop motion!
Thank you sir!! Stéph. Merci Monsieur!! Stéph.
12:50 "Everything has to do with this theorem." I loved this line. And it's true beyond "everything" in the example, everything in the Euclidean geometry world, anyway.
this guy is a gold mine
Excellent educational value. Teach theorem plus practical application in a few minutes .
I like the way he visualizes the spheres with his hands. It's almost as if I can see the spheres.
The animations are sick..🔥🔥🔥
i like the way he speaks, and is not a joke
Tadashi's little drawing is adorable!
Fantastic! Thank you Professor Tadashi!
Didn't expect to hear a Wilhelm on Numberphile!
As a Californian, I can't wait to try this out
I'd show this to my A-Level Geology teacher, but it's not a taught subject at my old sixth form anymore :(.
Interesting little nugget for anyone interested. The epicenter of an earthquake is the location on the Earth's surface that the earthquake emerges i.e. the location you would point to on a map.
The focus of an earthquake is the point in 3D-space within the bedrock that caused the slip that created the earthquake i.e. the point from which all the shockwave energy emanates.
this is fantastic.. a maths teacher with passion and ability to explain complexity with ease.. considering the copiousness amount dross on TH-cam this is quality.. thanks for posting. am looking forward to more :-)
absolutely fascinating
He's back!