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vertdider

vert_dider

vert

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исследования

научно-популярное

наука

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образовательный

образовательное

полезный

полезное

Дерек Маллер

Дерек

Мюллер

veritasium на русском

скорость света

длина метра

как измерили скорость света

как измерить скорость

скорость

расстояние

время

теория относительности

ОТО

СТО

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материя

антиматерия

вселенная

Эйнштейн

00:00:00

here is a site with shawarma works

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[music]

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I know what you just thought clickbait

00:00:11

no one measured the speed of light it’s just

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funny the speed of light is 299792458 meters per

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second we are so sure of this that since

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1983, based on the speed of light, we will determine

00:00:26

the length of a meter; this is the distance that

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light travels in a vacuum in a second

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divided by 299792458 from this

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definition it directly follows what exactly the

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speed of light is, well, smooth, but I

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assure you, and in this video I will prove that the

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speed of light can actually be

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completely different, I’m not kidding,

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no one has measured the speed of light

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and it can’t be fixed at all because

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the speed of ordinary objects is measured

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[music]

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everything seems to be written and so what will the

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video be about measuring speed h

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tell me how to measure the speed of a ball

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that you launch from a cannon for

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this we need to know two things first the

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distance between two points 2 the time it takes

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the ball flew from one to the

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other, then we just take the distance, divide it by

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time and get the speed,

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and with high-speed shooting you can

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count frames and there is a built-in

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timer, and now you’ll start again about

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relativity, as if you

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knew, I can’t believe it, oh my God, I also wanted to

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ask you about the speed of light, let's is

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it possible to measure it in the same way,

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imagine that we have a laser that

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shoots a beam through an ideal vacuum

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at a distance of one kilometer

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with the moment the laser is turned on and we start the

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cameras, we will stop it as soon as the light

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passes this kilometer,

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but how do we know when the light reaches

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the final point if there is a timer and we

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are at the starting point, apparently we need a

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second stopwatch; lasers are also at the end

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point of the path and the second one

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should stop at the moment when the beam is fixed.

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Now we need to synchronize the timer

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and they can be connected with a wire to

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transmit a signal from one timer to

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another, but here it is will

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travel at the speed of light and

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reach 2 devices with a delay, we

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could probably subtract the delay,

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but this is exactly the time it takes for

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light to travel one kilometer, and

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we don’t know exactly that, we’re trying to

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detect it, okay, plan b, we connect a timer and

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synchronize with each other, then

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we move it away 2 end point, what

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can go wrong here, I’ll

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explain how the clocks that we are moving

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move relative to the first ones, and according to the

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special theory of relativity, time

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flows slower

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than a stationary observer, and when 2

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cameras are in the right place, it is already

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synchronized with the first one, tell

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you how to cope with this difficulty,

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throw out 2 timers, put mirrors at the end of the path

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from which the light will be reflected and with

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one timer measure the time during which

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the beam travels two kilometers there and back

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you are here, and after all, I already did this, climbed the

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mountain there, they also took a wheel from a carriage, a

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lamp and at a distance there was just

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some kind of mirror standing, I always wanted to repeat the

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sau, well, it looks like you are now talking about how the

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speed of light was first measured by Hippolyte

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Louis Fiz in

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1849, he shined the light on a rapidly rotating

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disk with teeth, and behind, at a distance of 8

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kilometers, on a hill there was a mirror,

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spinning the wheel faster and faster, he

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achieved that that the reflected light fell

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into the gap between the teeth and it was

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visible, the visa came to the conclusion that the speed

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of light is 313 thousand kilometers per second, the

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deviation from modern data is only 5

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percent, so here we still measured the

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speed of light or not, so they measured the path of

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light in both directions

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there and back but the way in one direction is

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still no one and never I have

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one question for you I’m interested in what you

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will say that if light flies at one

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speed in one direction and the

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other in the other sounds like a typical

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veritasium video the question is is it possible

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check the essence of the problem is that

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in the end they measured only the average speed of

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light there and back, but no one measured

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it in one direction, it is possible that

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light flies in one direction 2 times

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slower than we think,

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and the return path travels instantly, why is

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it possible? Let's seriously

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imagine how communication with

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astronauts on Mars would work,

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let's call him

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Mark, we send a signal and receive a

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response in 20 minutes, we most believe that the

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signal reaches Mars in 10 minutes and

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receives a response in the same time,

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but it is quite possible that this signal takes

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all 20 minutes to reach Mars and the response arrives

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instantly and not, but for us

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both options look the same and

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we won’t even notice the difference, why

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the speed of light can be different,

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perhaps some directions in

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space-time he likes more

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in the universe, there is a lot of symmetry, but I

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symmetry occurs, for example, an imbalance

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in the content of matter and antimatter

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physicists have even developed quite

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consistent theories where the speed of

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light back and forth will be different, it

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may well be that the difference is only a couple of

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percent, or maybe light flies in one direction

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2 times slower than we think, but

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back instantly, so let

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me try to figure it out, so what? - I ca

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n’t believe it, I don’t believe it,

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I wanted to doubt that in one direction the

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speed of light can be one, in the

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opposite direction it’s different, but I know for sure that you

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wouldn’t have called me and

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filmed it all on camera

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if you weren’t sure that you were right and that’s

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me It scares

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me, I don’t like it at all. It’s fair

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to say that it’s easier this way when light

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travels in all directions at the

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same speed. The problem is that

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this is a rather conventionally accepted position;

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they are an experimentally verified fact;

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Einstein drew attention to this in his

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famous 1905 work on the

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electrodynamics of moving bodies from the first a

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couple of pages he discusses the problem of

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synchronizing clocks at points a and b and

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Einstein writes that it is impossible to

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compare the

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time of events without further assumptions unless one introduces the definition

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that the time

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required for the passage of light and for b is

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equal to the time required for the passage of

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light from b.v.

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he essentially equated the speed of light in

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one direction to the speed of light in the

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opposite direction and is highlighted in italics, and introduce a

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definition to remind us that this is

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just some kind of convention,

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this is actually called synchronization

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according to Einstein,

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thus the idea that the

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speed of light is the same in both

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directions he will write later is not

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a premise or hypothesis about the physical

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nature of light but a requirement that I

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make on the basis of free choice

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to obtain a definition of

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simultaneity

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I assume that many will find this

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approach too subjective for

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determining the speed of light oh wow

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I never thought about this yes I

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never thought about it before It always seemed that

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when we say that the speed of light is

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c, it means one-way speed

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of light, it turns out that it cannot be found, just

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calculate the average of both sides, look at

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how Einstein is determined through the path from

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point a to b and back, maybe you remember from

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school problems in which there were

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photoelectric clocks the light was already hitting

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upwards and reflected back and never

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only upwards, now it is clear why for

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an observer in an inertial

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coordinate system only the speed of

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light is constant for the journey there and back for more than a hundred

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years, scientists have been looking for a way to get around this

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problem to measure the speed of light in one direction and

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here is a work published in 2009 in an

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American scientific journal, the authors

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who stated that they succeeded, but here is

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a work in which they refuted this, saying

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that the previous authors measured the

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average speed back and forth, it

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seems to me that you probably have your own

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idea about how to measure the speed of light,

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here are some of them just

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turn on a high-speed camera that

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takes trillions of frames per second and

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see how the light passes through the object,

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but in this case the light must not only

00:09:10

pierce the object but also reach the

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camera, which means we again measure the

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double path he came up with, now

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we take a coil of fiber optic cable

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about 300 thousand kilometers then with

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this here and here is the second end of the cable,

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so we turn on the light and time how

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long it will take for it to appear at the other end. This is

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not a problem, the fact is that the fiber is wound and

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when the light passes through the upper part of

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the coil it can move slower, but

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when through the lower fast, in the end

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it will be average again, in fact, we drive the light

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back and forth, they are in one direction, but what if

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we place a synchronizing device

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between the clocks, the signal goes simultaneously in

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two directions,

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if the speed of light in both directions is the

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same, then our problem is solved, but if

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not, one clock will overtake others,

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and exactly that much, and that when we do

00:10:10

measure the speed of light, it

00:10:11

turns out that it is exactly equal to the prices,

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despite the fact that in fact this is not

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necessary speed like,

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for the same reason it will not be possible

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to synchronize the clock via GPS, the

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entire system works on assumption that

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light moves at the same speed in

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all directions, but if this is not so, then

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the signals from the satellites will move at

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different speeds, which

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means the clocks will move differently as

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a result, measurements will again show that the

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speed of light is equal to c even if this

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is not true,

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but it can synchronize the timer and at

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one point and move their

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opposite sides away and at the same

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speed, the time dilation for them

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will be the same, which means they will move

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synchronously, but this will only work if the

00:11:00

speed of light in all directions is

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the same,

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if not, then the time dilation for the

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clock will be different, perhaps it seems to you

00:11:09

that if you move the clock very slowly,

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time dilation can be neglected, but

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if light moves at different speeds

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depending on the direction, then the usual

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formula for calculating time dilation will

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no longer work for us and the effect may turn out to be

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much significant than you think, it

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turns out that we are at a dead end,

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to measure the speed of light we need

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synchronize timers,

00:11:31

but in order to synchronize them you need to know the

00:11:33

speed of light in one direction, it may

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seem that this is exclusively a

00:11:37

problem for scientific minds, but let's

00:11:39

see how the understanding of

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processes in the universe will change if the speed

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of light is observed in different directions,

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let's say Mark the Martian decided to

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synchronize his clock with ours,

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noon on earth for him communication with

00:11:54

text is sent signal sent 1200 having received

00:11:58

the signal and taking into account the synchronization of Einstein,

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mark sets the time, he knows that

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the signal reaches Mars and returns

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to earth in 20 minutes, divides this by 2 and

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now he has 12 on his watch 10

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mark sends a message signal

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sent at 1210

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to on earth the message is received in 20 minutes 1

00:12:20

and everyone understands that now the clocks are running

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the same when the clock in NASA shows 1220, the

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mark on Mars is also 1220, but imagine

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what happens if the speed of light in

00:12:32

different directions is not the same,

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let’s say in the direction of Mars this is c divided by

00:12:38

2 and the signal gets back instantly,

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of course, no one knows about this and everyone

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still relies on

00:12:45

Einstein’s synchronization; he sends a signal to the earth, but it

00:12:48

goes to Mars for twenty minutes;

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Mark doesn’t know about this either, he is sure that the

00:12:54

message was sent 10 minutes ago and

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sets the clock to 1210, although he is already on earth

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twenty minutes March 1 writes a signal

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sent at 1210

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be the message instantly arrives on

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earth on the NASA watch

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1220 the participants in the conversation will not even

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suspect anything the message seems to arrive

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with the required delay, but their watches now

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differ by 10 minutes, it turns out that

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they will count simultaneous on earth and Mars It’s

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not the right events to

00:13:26

find out about this or fix something, there’s no way we’ll be

00:13:29

able to assume on earth

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someone will write how long it

00:13:34

took for this signal to reach you, we have 1220 the message

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will reach Mars in 20 minutes but due to the

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different time on Mark’s watch it will be

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12 30 it will respond in 10 minutes, his

00:13:47

message will be instantly received on earth and the

00:13:49

clock will read grade 12. The

00:13:53

space-time diagram

00:13:54

perfectly illustrates the relativity of the

00:13:57

concept of simultaneity of distant

00:13:59

events reflections and how different the

00:14:02

speed of light can be.

00:14:04

Einstein preferred to dwell on the fact

00:14:06

that it is the same in any direction but from an

00:14:09

experimental point In terms of perspective, any

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other view of this is no worse,

00:14:13

including the one in which light travels in one direction

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at a speed of

00:14:18

half c and in the other instantly, but then it’s

00:14:22

interesting to think about what the

00:14:24

participants in the exchange of messages see when looking

00:14:26

at each other. Mark will see the earth 20 minutes

00:14:30

ago. On Earth, Mars can be observed in real

00:14:34

time as it is right now, and

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this applies not only to the red planet,

00:14:41

look around and see stars hundreds of

00:14:44

light years away from us,

00:14:45

and not as they were hundreds of

00:14:47

years ago, but exactly as they are

00:14:49

now; we also see light only

00:14:55

when he reaches us about how

00:14:58

exactly he reached us, we don’t know anything, we

00:15:01

see him, that’s all in one moment, don’t

00:15:04

assume that he reached us instantly,

00:15:06

no worse than at a speed equal to c,

00:15:08

my brain is broken, yes, yes, it’s like

00:15:13

just as I didn’t find out there and I’m talking about the video, the

00:15:15

point is that this

00:15:18

convention about which Einstein wrote in

00:15:20

1905, you decided that the speed is in

00:15:23

all directions, while the laws of physics

00:15:26

will continue to work even if in one

00:15:28

direction twice less and backwards and

00:15:30

instantaneously or something else

00:15:32

average speed back and forth from

00:15:34

physics is fine this is what breaks the brain and

00:15:38

so soon we don’t know the light in one direction

00:15:40

but for physics this essentially does

00:15:42

n’t change anything why talk about

00:15:48

this approach at all shared by many participants in

00:15:50

the discussion, which stretches back to

00:15:54

1905; some physicists recall

00:15:56

Occam’s razor; after all, everything is much simpler if light

00:15:59

moves in any direction at the same

00:16:01

speed;

00:16:02

many scientists simply accepted this

00:16:03

convention;

00:16:10

has empirical evidence, I am

00:16:16

fascinated by the very fact that nothing in the

00:16:19

universe is hidden from our eyes, yes, we

00:16:22

know at what speed light travels

00:16:24

from a source to a point and back, but

00:16:27

there is a one-way speed of light, a

00:16:29

clearly defined value, if not, what does

00:16:31

this mean for the concept of simultaneity

00:16:33

when on Mars there is a moment called

00:16:36

right now, if at all it makes sense to say

00:16:38

that some events occur

00:16:40

simultaneously if they are separated by

00:16:42

a distance,

00:16:43

perhaps this is just a random quirk of

00:16:45

the universe that means nothing,

00:16:47

or maybe you then physicists will experience

00:16:50

another breakdown of the paradigm of measuring the

00:16:53

speed of light, which is now for us

00:16:55

inaccessible will be the key to how

00:16:58

the theory of

00:17:00

relativity and quantum mechanics are connected,

00:17:02

space and time, and we will be surprised

00:17:06

how you haven’t seen this before translated and

00:17:10

voiced by Virt Give Dar studio

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Поддержать проект можно по ссылкам: Если вы в России: https://boosty.to/vertdider Если вы не в России: https://www.patreon.com/VertDider Скорость света — одна из самых важных констант в физике. Учитывая, как активно и успешно её используют во всевозможных расчетах, сомневаться в достоверности её значения было бы странно… вот только никто не знает, сколько времени нужно фотону, чтобы пролететь из точки А в точку Б, мы знаем лишь продолжительность путешествия туда-обратно и предполагаем, что скорость одинакова в обоих направлениях. Но что, если мы не правы, и возможно ли как-то это проверить? Об этом и расскажет Дерек Маллер в новом видео. Перевод: Елена Смотрова Редактура: Алексей Малов Научная редактура: Кирилл Циберкин Озвучка: Дмитрий Чепусов, Алексей Никитин Монтаж звука: Андрей Фокин Монтаж видео: Джон Исмаилов Спасибо за поддержку на https://www.patreon.com/VertDider. Озвучки Vert Dider выходят с вашей помощью: Pavel Dunaev, Oleksii, Yegor Barakovskiy, mrwiseguy351, Ігор Дорохов, Mikhail Stolpovskiy, Rashid Nasibulin, opperatius, Dina Kruchina, Alena, Vitaliy Vachynyuk, Ника Калмыкова, Nadia Kilgishova, Роман Чурин, Aiorraro, Евгений Сельменев, Alex Afalex, Anton Kudashov, Владимир Кашутин, Pavel Parpura, Anton Bolotov, Yevhen, Sergei W, Kosoy, Данил Рягузов, Михаил Панькин, Anton Makiievskyi, Максим 'Sheridan' Горлов, Katoto Chan, Stanislav K, Edward Ben Rafael, Юрий Медведев, Анна Троссман, Serj Skidan, Andrei Chitaev, L Marchenko, Sultan Ishankulov, Александр Яковлев, Mike Sviblov, Andrey Rusanov, Inna Klymenko, Dima Chumakov, Dmitriy Lashtaba, Olesya Bolobova, Ilya Alexeevsky, Alexander Balynskiy, Максим Иванов, Ольга Канкулова, Alexander, Viktor Lova, Maria Tronina, Sergii Cherepanov, Alexander Gorodok, Ivan Iakimov, Alexander Zimin, Евгений Миф, Виталий Пастушенко, Serj Kravchuk, Claudia Barzaeva, Pandaben, Monza UA, Lirin Alex, Pavel D, Konstantin Pesyakov, Denis Titusov, Alterien, Viktoria, Alexandr Globov, Oleg Streltsov, Olga Podolskaya, Alexey Kukushkin, F23D24, Пугачёв Пётр, Olga Shistareva, Kamerton_440, Alex Katkov, Alexey, Irina Shakhverdova, Vladimir Grachev, Dmitriy Omelyansky, Maria Burtseva, Aleksey Sazonov, Vladimir Goshev, Vladyslav Sokolenko, Дмитрий Мисюра, Anton Novozhenin, Spartak Kagramanyan, Александр Фалалеев, Evgeny Vrublevsky, Yuliia Zinko Сайт студии: https://vertdider.tv/ Мы в социальных сетях: — http://vk.com/studio_vd — https://t.me/vertdider — https://twitter.com/Vert_Dider — http://coub.com/vertdider Разрешение на публикацию: https://vertdider.tv/permissions-for-publication/ © https://www.youtube.com/user/1veritasium Источник: https://www.youtube.com/watch?v=pTn6Ewhb27k

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