Neil deGrasse Tyson Explains Time Dilation

[Music] I still lose sleep over this fact okay I still lose sleep over it and I want you to lose sleep too

I don't want to be the only one staring at the ceiling at night I'm GNA tell you uh a lot of things already beat you to that oh sure mean the asteroid strike that could happen or the exactly right

right with the global warming or all right so here it is you may remember or you may have heard that Einstein's relativity right more more specifically

you learn this in special theory of relativity where the faster you move right the slower time ticks for you

right as others view it relative to The Observer relative to The Observer correct you don't know anything's happening right your clock still ticks as far you still got your your heartbeat

all of this okay so this is not physiological thing is an actual property of the fabric of space and time

under those conditions wow okay that is fascinating it is it's completely fascinating it's completely so I watch you fly by and the faster you go the

slower time ticks for you okay but my time stays the same to you to me right to you so not only does speed do this also the strength of a gravitational field

will have the same effect on you the stronger the gravitational field is the slower time ticks for you and that wasn't formulated until his general theory of relativity um 10 years later

that took a lot more math and and and deeper insights into the universe so once again it makes sense because you're dealing with the fabric of SpaceTime it's the fabric of SpaceTime correct but

initially when formulated you're thinking it's just because you're moving but it's it's it's actually way deeper than that and that's why that oh by the way his original special Theory relativity was not called that the title

of the research paper was on the electrodynamics of moving bodies what okay that was that was the title we would later call it the Special theory of relativity because it was a special case of what would later then be called

the general theory of relativity oh oh while we're there let me just slip this in the GPS satellites orbit higher than our um than our than like the space

station and and other things that are in what we call lower Orit Mo Middle Earth orbit there Leo Mio and Geo okay if you have kids maybe you name them that yes

Leo Mio and Geo low earth Orit Middle Earth orbit and geosynchronous geo geo orbit okay so the the geosynchronous satellites are

are like middle orbit that is far enough away from Earth's source of gravity for them to have a different a measurably

different SpaceTime condition oh so that their clocks tick faster than our clocks on Earth's

surface because they're farther away and so remember I said the the more intense the gravitational slower the slower time tick so they're farther away their time

ticks faster relative to us wow but we get precise timings from geosynchronous

satellites so how does this work we prec correct the time signal from the GPS satellites to compensate for Einstein's

general theory of relativity so that by the time the time reaches us what it's been properly corrected and it matters to us an our SpaceTime Continuum not the

one that's in middlee orbit oh my goodness so GPS couldn't work as accurately as it does however wait a minute I'm sorry just for me you would

have to have a standard in order to precorrected up because you can calculate what the gravitational field is up there there you go there you go

okay okay and once you calculate that then you do and you say oh my gosh we the the the formula Works Einstein was right all right this is not just

something on a the high Theory hypothesize that may or may not not be true it is true I just want to be there when that phrase is uttered oh my God

Einstein was right yeah these aren't just cult Heroes that we wish they were right these are real this is real okay this is the real Universe we're talking about here okay

so now watch let's keep going faster and faster let's go half the speed of light 3/4 of the speed 90% the speed of light 99% the speed of light time is taking

slower and slower and slower for you you will watch the whole future history of the universe unfold in front of your

eyes as fractions of a second go by for you as you go 99 there's a formula for this of course but 99 99.9

99.99% the speed of light because you're the Observer of that but for you your time has slowed to the point where As

You observe the things that are not moving at the speed of light you see them speeding basically you see unfold

correct boom God correct that is insane so now watch oh my God wait now watch okay wow so I didn't even get to the part where I

lose sleep okay okay that's what happens by the way by the way um there are particles that decay you've heard of like radioactivity right yes it's one

part it decays and becomes another part it releases often deadly energy yes okay radioactivity all right some particles let's take for example the uh

proton uh or the the muon one of these uh it decays in like six minutes when it's left out in the in the wild okay when it's not part of an atom when it's not in captivity uh I

forgot which of these but it doesn't matter for my example Decay is in like six minutes okay okay what happens if you take that particle and speed it up in a particle

accelerator so you take a a a community of these particles speed them up calculate wait a minute the internal wristwatch on these clocks says they

should live longer and sure enough their Decay time takes longer wow that's oh my God yes yes so oh wow yes and that

becomes that becomes living proof of what Einstein said yes cuz we can't go half the light you can accelerate a particle to do that has an internal buil-in clock that decays after a

certain amount of time and there they are taking longer to decay in the exact amount that Einstein predicts that is genius so we don't make this stuff up

okay it yes it is genius this like triple genius all right now let's take this to an extreme level right let's go so

fast that we're going the speed of light itself right right well we can't do that cuz we're made of material substance and that's there's no way to do that but there are things that travel at the

speed of light and what is that uh those would be photons yes thank you I like those would be I like your finger gesture that would be I would say

what travels at the speed of light light does yeah okay I was about to say light so if photons had a clock

the clock would never tick nice which means when I go to a Mountaintop as I did in graduate school

to observe the center of the Milky Way galaxy for stars that emitted their light 30,000

years ago traveling through the gaps of interstellar space and they move through space come through Earth's atmosphere they come down into the T scope they

reflect go back to my detector and land on my CCD chip that Photon when it was

born at the star that emitted it was detected at my telescope in the same instant wow

according to the photon itself live fast Die Hard Fon has no knowledge of that trip right because

time did not exist for it oh that's great and I'm saddened that many of these photons like hit people tanning on the beach you know and and to imagine

Trav 30,000 years and land on someone's buttocks could with the telescopes I collected I'm now decoding the nature of the universe not and some photons go

right on by Earth and are still moving but they have no internal time clock wow and they're just traveling through like I hope when I'm born I hit a telescope

bam you're born and you're hit a telescope yeah yeah I would that would be an interesting but when I what do I want to be when I grow up you know or the instant I am admitted where am I going to be where would I like to be

right right right and so just the idea that light can move across the universe and have no uh and not age this is a fascinating fact to me

wow so yeah that is that is more than fascinating that is I mean that's mindboggling yeah yeah so that is light the age of light it's like it doesn't age at all I am convinced that all of

you guys secretly micro do and smoke weed I'm just another episode that's what I'm saying another episode all right Chuck we're calling it

qu there all right all right mysteries of light and time uh Neil grass Tyson here keep looking at yeah

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