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  • hello my name is Michael and welcome to dawn the first and only YouTube channel

  • made by of and for teens who like cooking today we're gonna be talking about

  • babies babies are being born all the time in some countries they're born more

  • often than others this website neil dot fun slash a baby map lights up each

  • country on earth at the same rate that babies are born in that country so as

  • you can see India and China light up a lot if you watch long enough you'll get

  • a little UK blip that's a baby being born I mean not like we don't it's on an

  • exact baby but the country's light up at about the same rate as the country's

  • birth rate so you can really get a sense of where people are being born you know

  • to be honest humans are like one of my top ten favorite animals let's keep

  • talking about humans and how many of them there are with population

  • bracketology this website sets up a bracket of cities and then it's your job

  • to figure out who would win in a battle of who's got the largest population I'm

  • gonna change it from metro area to state population make a new game uh some of

  • these states have a by weeks but let me see here between North Dakota and

  • Illinois Illinois clearly is gonna win it's got big cities it's got Chicago oh

  • when you click Illinois there you go now between Idaho and Vermont Vermont is not

  • very populated but Idaho I'm gonna go with Idaho sure close one all right

  • between New Mexico and Massachusetts Massachusetts definitely has more people

  • and between Idaho and Massachusetts obviously Massachusetts does but between

  • Illinois and Massachusetts that Chicago versus Boston and that Boston metro area

  • is quite expansive but I'm gonna go with Illinois Bob Chicago is like the number

  • three most populated city I will keep playing this on my own time so I don't

  • waste yours we need to move on to outer space specifically people who have been

  • there travels in time and space allows you to look at astronauts from all over

  • the world from every country even the commercial and tourist astronauts right

  • now I have my axes built so that I've got the length of trip on the vertical

  • axis the further down we go the longer the person was in space and

  • the horizontal axis is when their first launch occurred so if we go to the very

  • furthest dot and click on it yuri gagarin first human being in space

  • he only spent point zero eight days in space so he's well didn't have a very

  • long trip if we go to more recent launches you'll see that some of these

  • dots have white circles around them those represent people who are currently

  • in space astronaut scott tingle what's up

  • you obviously eat little bit the astronaut ok astronauts don't just

  • travel through space they also travel through time like we just did my beards

  • longer sure it's different continuity isn't really a priority here

  • at Vsauce headquarters but what is a priority is learning let's take a look

  • at this graph and change the horizontal axis to represent time dilation there is

  • clearly some function that defines how you move through time when you are

  • moving through space and where you're moving through space check this out

  • the world record for longest time in orbit is held by cosmonaut padalka who

  • spent 878 point 48 days flying very quickly around the earth and because of

  • that padalka is about well more than 25 milliseconds younger than he would have

  • been if he'd stayed here on earth that's because of time dilation now when you're

  • in orbit time moves for you at a different rate because of two different

  • effects special relativity and general relativity if you want to learn more

  • about these I highly recommend these books

  • first of all Martin Gardner's relativity simply explained a fantastic but my

  • favorite book that I read in all of 2017 was Lewis Carroll Epstein's relativity

  • visualized just phenomenal but if you want to get even deeper you can go a lot

  • less wrong than getting the Taylor wheeler spacetime physics book just

  • unbelievable explanations we've also got videos linked down below where you can

  • learn more but the gist of it is this when you are orbiting around the earth

  • you are moving faster than people who are just still down on earth at rest

  • relative to you and that means that time moves more slowly for you a person at

  • rest down on earth if they could take a telescope and look at your watch would

  • literally see your watch moving more slowly you would be aging more slowly

  • you would be reaching your date of death slower but also the higher up you go the

  • weaker the gravitational field around you will be and that will cause time to

  • go faster for you these two effects combined into this

  • blue line that we see here this red line represents time dilation due to orbital

  • speed and as you can see the larger your orbital altitude is the less quickly you

  • have to move to not crash into Earth and so the smaller the effect is now this

  • green line represents the general relativity effects the gravity well

  • getting weaker and as it does you move through time faster and faster and

  • faster their combined effect is this blue line labeled net orbital time gain

  • now astronauts in the National Space Station are at about you know this

  • altitude a few hundred kilometers and that puts them on the blue line down

  • here meaning they experience less time than us down on earth

  • that's why padalka is about maybe 30 milliseconds younger than he would have

  • been had he not gone into orbit if you'd like to see how you have been moving

  • through time time orbit will help a lot the University of Surrey created this

  • app and it takes information about your altitude and motion to compare how you

  • have moved through time since installing the app compared to someone who has

  • spent that entire time motionless at sea level fun fact about 3200 kilometers

  • above Earth's surface a little shy of 10,000 kilometers away from Earth's

  • center both effects exactly cancel out and no time dilation is experienced

  • relative to someone at rest down on earth anywho I'm sure you have a lot of

  • questions for instance Michael that's cool but what I don't understand is how

  • long can a zucchini grow I'm glad you asked because the world record for

  • longest zucchini was set by giovanni battista Scozzafava of Niagara Falls he

  • grew Sukie knee two point five two meters in length it's just phenomenal

  • but it's actually not that weird zucchinis like to grow big they just

  • don't taste great when they're large ideally

  • zucchinis are picked when they're young no more than 12 inches long so if you're

  • taking notes don't forget that one I also go back to Lightspeed when you're

  • traveling really quickly all kinds of weird relativistic effects occur okay

  • time dilation happens obviously but also measured whips change here's a

  • relativistic car now I can use this slider here to make the cars velocity

  • slower or faster I can speed it up and notice that as I speed it up the car

  • appears to contract and become thinner and thinner and thinner until at the

  • speed of light boom it is well it doesn't have any measurable dimension in

  • its direction of travel we've heard this before and I've talked about it before

  • in episodes about whether the earth is flat or not to a particle traveling near

  • the speed of light the earth would be measurably flat like a disc but would it

  • appear to be a flat disc no because of an optical illusion known as a Tyrell

  • rotation here's an example from Wikipedia of what that looks like

  • I think this animation is brilliant so on the right we have the actual visual

  • appearance of a cube flying by at some proportion of the speed of light and on

  • the Left we have the contraction the actual width of it that we would measure

  • but notice that at 99% the speed of light it almost is completely rotated so

  • that we see the other side of it here's a way to visualize what a Torrell

  • rotation is and why it happens here's a cube now let's imagine that this cube is

  • just moving right past you at some point it's gonna be right in front of you and

  • then it's gonna move away now normally it would look like this it's not moving

  • very near light speed you can't see the back of the cube I mean you can because

  • this one doesn't have any opaque sides but the point is that material over here

  • isn't reflecting light to your eyeballs we can imagine that this green stick is

  • a ray of light any light coming from this back edge right towards you that's

  • getting blocked by the fact that the cube or the shape whatever shape it is

  • might be opaque but if this stick represents how far light travels in a

  • second and it's got to travel like this to

  • to your eye if the object is moving near the speed of light it might be able to

  • move out of the way of that beam of light and not block it so it will reach

  • you you'll see the back of the object as if it is actually rotated so an object

  • traveling near the speed of light will appear to rotate like that it's only its

  • appearance it won't actually be rotated and if you tried to measure it you would

  • find that its length had contracted let's watch a video of this effect space

  • time travel org has a great one and what you see is a bunch of dice and they're

  • all in a row but then above them a die is gonna fly by I think actually a few

  • died known as dice will fly by in the same orientation but they won't appear

  • to be in the same orientation here they come

  • all right not looking too weird yet but as you'll see the closer they get to us

  • the more rotated they are until boom right there we can actually see the back

  • of the cube even though the back is not facing towards us this relativistic

  • effect is called a Terrell rotation and I love it when it comes to relativistic

  • effects who can forget red shifting and blue shifting of electromagnetic

  • radiation not us right and also not velocity Raptor in this game the speed

  • of light is much much much slower so the normal speed of Velociraptor can move at

  • is quite close to it so relativistic effects occur now here's the level and

  • what I need to do is get to this yellow exit door

  • but wait these bullets are kind of close together I should probably be able to

  • fit through them let me start moving my velocity will change oh and look the

  • entire game level warps according to how length changes which means if I go up

  • the bullets get closer together I can spread them out by moving down now I've

  • got room great whoa whoa whoa whoa okay don't you don't to fall in the water if

  • you ever want to center yourself on your character I think you press C yeah okay

  • there you go I find this interesting but not nearly as helpful press C again to

  • go back also notice that my velocity it's like I'm playing asteroids if I

  • stop pushing the key moving at the same velocity but spacebar

  • will freeze yourself let's save your life many times now

  • let's look at these keys in order for me to open up this lock I need all of the

  • keys to have the same color which means I need to find the velocity that

  • redshifts and blueshifts them so that they match now remember velocity is a

  • vector so there's also a direction to it so I don't just need to have the right

  • speed I need to be moving at the right speed in the right direction

  • all right I'm able to get these two near in color but how do i okay for that one

  • I have to move left and right I think now I'm getting it really to purple oh

  • wait that looked but I want to move towards the bullets all right so moving

  • to the right is the opposite of what I want to do let's see what I can come on

  • change color yes nice and that's how you do it when you are an expert at the ways

  • of the universe I'm gonna leave you with well honestly a bit of motivation we've

  • all heard of the company Arm and Hammer right they were founded 151 years ago

  • the brand was in use about 31 years before the birth of a man named Armand

  • Hammer yeah no relation he had nothing to do with founding the company was a

  • named after him but as you can imagine good old mr. hammer

  • Armand to those who were familiar with him got constantly teased for having a

  • name that sounded like the brand Arm and Hammer so what did he do well when he

  • got older got enough money together to buy enough stock in the parent company

  • of Armand Hammer to become a part owner that's right so Armand Hammer became a

  • board member of Arm and Hammer so my question for you is this what are you

  • doing today that will be strange enough that one day it might be discussed on

  • Daum stay curious stay hungry be sure to

  • pre-heat your oven and as always thanks for cooking Bon Appetit

hello my name is Michael and welcome to dawn the first and only YouTube channel

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相対論的効果 (Relativistic Effects)

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    林宜悉 に公開 2021 年 01 月 14 日
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