How Fast Is It - 02 - The Speed of Light (1080p)

[@stelpap6768]

mr Butler you are truly the best.

[@richardavery2894]

Agreed. He is the best 👌

[@To_Orion]

You're the single most legendary tutor I've ever seen. All my questions without them asking to anyone get answered here.

[@feelingzhakkaas]

Dear Respected Sir, You are among THE BEST in explaining this subject. Wish my professors during my college time were like you. You are simply Great. God bless you.

[@mylesbishop1240]

Prakash Kamath thanks

[@halfbloodpirate-]

You taught me so much, you taught me astronomy... imagine a kenyan? And i know so much from you.thank you sir.. you made me fall in love with space..my wish is to have a telescope.

[@freedom_aint_free]

As a science professor, I can say that your didactics is absolutely flawless Mr. Butler!

[@pcchauhan6255]

baianoise

[@pcchauhan6255]

baianoise qdgdc mlsas and

[@123ubuntu666]

It's very obvious to me that David Butler is a person who has what might be a unique gift when it comes to describing information or teaching. Mind blow. On several levels. Some at the same time.

[@StrangerThenRedz]

this is the best set of science videos just right for beginners while summaries & recap for others

[@cidshroom]

You dropped all of these on us in 1 day! *ok deep breaths, slow that pulse*

[@griffith500tvr]

I love how you as an American use the Metric system

[@tetkinsin]

I have waited your new upload like a stone Sir Butler!

[@neoneo4221]

My man butler be ballin

[@RandyMarsh20]

He comments from time to time just to slap up the smooth brains in the comments, straight G

[@kraxzor]

Your Videos are by far some of the best on these subjects. I really appreciate how well you lay everything out.

[@pablosteelio9462]

David Butler is a scientist. Scientists use the metric system because it is superior to the size of some old king's foot. It is you that needs to change not the whole scientific community. Thank you, Mr. Butler, your videos are great.

[@7kennyg]

Its not the length that matters as much as the way the units are divided. If a unit is divided by any number other than ten you will end up with a mixed number and then a calculator cant be used.

[@Tadesan]

The metric system is perfectly arbitrary too. How is a millipound any less useful than a milligram? The main argument for the metric system is that it is founded on plain old good ideas and has a lot of momentum. It's like Christianity except for I like it...

[@TheGreatAlan75]

Feet and inches are the best. FUCK the metric system

[@ynoten]

@@TheGreatAlan75 Its called the international units of measure for a reason, dont see imperial units being that. Youre 1 of 3 countries in the world holding on to those messed up units, though, your scientists uses metric, they know whats good.

[@seankaelin8068]

I wish I could have found these years ago the way you describe and inform us is amazingly easy to grasp and actually comprehend this subject matter better than anyone else I have listened to yet! Thank you!!

[@ceilingfun2182]

Definitely. I just wanted to make my comment short, but but I’m having the same thought right now.

[@stevenreichertart]

I've been watch your videos, and I just want to say how thankful I am for the time that you've put into these videos. I appreciate your quiet, calm teaching. As an extra bonus, your videos have been soothing to me and I use them to help fall asleep because I have problems with insomnia. Your quiet voice often puts me to sleep. But I hope you don't take offense; the next day, I pick up where I left off to finish watching! Thank you again.

[@123ubuntu666]

Never have I seen someone abstract so many abstractions and reconstitute them back in to reality, which is the ultimate abstraction, the end goal of abstracting. Visual, relative, metaphorical, intuitive and counter-intuitive abstractions are made, but always beautifully boiled back down to illustrate the point. What an incredibly gifted teacher and communicator David Butler is. "Mind Blow" indeed.

[@ibite100]

agree

[@Mr123tallpaul]

Sir, these videos are a joy. My immense gratitude.

[@cyruskalali8222]

The most interesting and enlightening video on these subjects. Very avademic and easy to understand. Thanks David

[@Dynamit-fy7hw]

You sir truly are a magnificent teacher! I have enjoyed your videos for a while and am very happy to see that you have posted all of these at once. Keep it up.

[@kennethdobos9755]

There is something very comical about seeing the snail with the graph. Its funny and cute at the same time. I guess it was the background music and serious narration.

[@atkmachinei]

Just want to say thank you for these amazing videos! Keep up the good work.

[@gangreneday]

Your videos are amazing! Thank you for uploading these. Incredibly informative.

[@clayhall9331]

Love your videos and thank you for releaseing them all at one time. Although, it would have been kinda cool for you to have released them daily, like a tv mini series. Nevertheless, you rock!

[@craigvanantwerp7141]

When I was 8 years old on a road trip with my family I asked my father, "how long would it take a snail to travel around the world". I was ridiculed for asking such a stupid question. In my teens I worked it out myself. If only I had a teacher at that moment I would have been given a treasure of understanding.

[@MrKmanthie]

Craig Vanantwerp ...whomever it was that ridiculed you probably did so because that person wasn't intelligent enough to probably even understand such a question, let alone know how to answer it!! Good for you. Glad that you kept up your curiosity & were able to figure it out.

[@vamthekam]

@@MrKmanthie it was his dad dumbass

[@MrRofl131]

Best music choice ever for the snail speeding record.

[@hardygeoff159]

When life presents questions, your videos sir always answer them , thank you for sharing your experience & knowledge to us mortals.

[@jaezryl]

Wow wow wow, this is the stuff that my professor failed to elaborate. I can't understand how we got the conundrum of "Light speed is the same at all reference frames". Thank you sir.

[@halfbloodpirate-]

You explain fantastic..

[@justinhorn2395]

Best ASMR out there

[@petergreen5337]

Thank you publisher ,very good explanations.

[@richardhogan7187]

I can understand this but when I talk about it to people that haven't studied it, they think I'm having flashbacks of dungeons and dragons or star trek. My Dad even thought I started smoking weed. Thanks for the publish of good information.

[@carlospinedadelgado89]

Richard Hogan im high af and this is amazing, i regret not to put attention to my math teachers at school.

[@keithlavallie6968]

I am a very big fan of all your tutorials. You explain things in a very easy to understand way. I am fascinated with everything space. It blows my mind. And the more I learn the more fascinated I become. Thank you for doing what you do!

[@GottgleicherMaster]

finaly and all videos at once. your style and your voice are just unique :)

[@porsa0]

That KSP image :)

[@migfed]

Im a colombian guy, thanks so much, you videos are of such a great quality.

[@gpgis]

Amazing Video David.

[@MrVolodus]

18:00 , that experiment is amazing. Simple and amazing.

[@Crozz22]

You are a world class teacher. Greetings from Norway!

[@pruthvipalsolanki2465]

The Best content seen Keep it running mr. Butler

[@pererau]

Thanks for using the Raindrops Prelude. One of my all time favorites

[@magrathean0]

Very Good. Thank you

[@CalSprigley]

I’ve seen other videos about relative speed and none have explained it so well

[@MrKmanthie]

Hi David. I like that microphone you have set up on your desk, e.g., the part near the end, where you, basically, recap the topics & set the stage for the next chapter. thanks for the great work!

[@BloobleBonker]

Love the William Tell overture as the snail shoots along. Hi Ho Silver! Your video's are so well presented and thought out. I wish I could have seen them when a student.

[@dannypalo1227]

I love all your videos sir

[@dshaboy]

Thank you for these videos they are fantastic!

[@arminiushermann09]

I like the voice, it's soothing an relaxing. It's those type of voices that I always learn a lot.And it makes me want to keen in an really pay attention. Plus it's always those type of voices that teach the subject in a manner that everyone can understand it, an where you want to learn more.

[@worfoz]

The Rob Ross of physics.

[@Jimmybarth]

Yes the boss of physics 👏

[@rayhughes]

David, thank you for all of your series - I would like u to know that my interest in astronomy is outweighed only by my ignorance of math - you have certainly helped to bridge that distance somewhat - Thank you sir

[@jmscnny]

That was a half an hour well spent. Thank you.

[@RigmorCyrodiil]

Love you David...and your back yard xx

[@Lesca6]

Thank you for your videos. Great work. And an nice narration. Your voice is matching the content perfectly. Not to fast, not too slow. Kinda calming (and full of nice facts). Better than 99.99% of the things on tv, today (and I mean the scientific stuff). Keep up the great work. One sub earned. Have a nice day ;)

[@tristanbaravraham6349]

I binge your stuff big time! Thank you for posting your works. Pretty weak comment BUT true ;-)

[@davidgodzik7093]

I wonder if the people who disliked this video can explain it more clear for me

[@circusshizshow]

They're flat earth idiots.. So, no.

[@lezlezman1843]

Fizeau's method for measuring light speed was so simple and yet so ingenious. I'd never heard of him until seeing this. I had already known of James Bradley and his aberration of light method and, although it turned out to be more accurate, it was complex and took about a year to take the measurement. Fizeau's method is quick and could be replicated by just about anybody who wants to make the effort of doing so. As I say, simple but it took creative thinking to come up with it.

[@ChrisMinjaeKim]

these are amazing! thank you!

[@danielthesantos]

Either your back yard is magical or you are, because every time we start there amazing things happen!

[@gaminawulfsdottir3253]

This is an excellent video.

[@Emdee5632]

9:08 The Parker Solar Probe (PSP) reached 531,670 km/h when it was just 10.4 million km away from the sun on April 29, 2021. That is almost 148 km/s or almost 92 miles per second.

[@wingy200]

9:09 I can't help but notice that this probe appears to be built using Kerbal Space Program. I would love to watch Scott Manley interview you so we can learn more about you.

[@pedrazzinig]

well done

[@gertebert]

Your voice is very nice to listen to. Thank you for al those informative video's.

[@Núi_Lang_Thang]

Please do another chapter of How Slow Is It

[@galaxia4709]

+Hidari Qantas - Or about How Mysterious Is It, about the things we don't know :) Can't wait for another series!

[@lebensraummetal]

Chuck was the first man to break the sound barrier in *level* flight.

[@domenicoteodonio6421]

The Helios-A probe in 9:08 comes from Kerbal Space Program :) nice reconstruction

[@LBCreateSpace]

The music at 1:13 killed me 😂 so funny

[@kiibo_ouo]

Thx david

[@jeffy141]

love those videos

[@jatatanglobustead3963]

Hi, I have a comment and a suggestion. My comment is that I like how you blew right through all the speeds right to the speed of light. My suggestion is that you add how many times the speed of light each speed is after you discuss the speed of sound.

[@jayeshkawli]

Hello! Nice videos, extraordinarily informative. Just curious, which software do you use to create animations in videos? That looks awesome by the way.

[@fredeagle8766]

the Frenchman, Fitzhue, very clever.

[@nickharrison3748]

U r great in Explaining

[@88diabola]

lovely sandals

[@stevendixon1339]

So in the Michaelson - Morley experiment there was no shift in the interferance pattern. Does this suggest that there was no change in the frequency of the light, perhaps due to the constancy of the speed of light? This has me thinking that the fact that the speed of light is the same for all observers should eliminate redshift / blueshift observations? Many thanks for pointing toward the reason we see redshift and blueshift. I seem to be stuck in the old transformation paradigm!

[@howfarawayisit]

+Steven Dixon I think you are mixing the frequency (wavelength) of a photon with its velocity (c). Changing the frequency does not effect velocity.

[@stevendixon1339]

+David Butler Thank you. So thinking about the two photons traveling toward each other in the next video (beginning @ 10:40) - one from Deneb and the other from Altair, from the reference frame of the photons, each photon would see the other traveling at the speed of light and each would see the same degree of blueshift in the other photon's wavelength? Does space contraction affect the observed blueshift from the photons' point of view?

[@howfarawayisit]

Yes. But the amount of shift over small periods of time (millions of years) would be too small to measure.

[@garypower864]

Hello Mr Butler hope you’re well and life’s treating you good as well. Gary Power from Liverpool in England, I’d love to look at Anfield, home of Liverpool football club, I don’t know if you follow English football but yeah I’ve been all over Europe watching the mighty red men I’ve been watching your documentaries on me phone in my room in the hostel I’m living in an I just thought I’d say your proper boss at explaining everything so thanks mate

[@Rehash84]

How do you scouse lunatics manage to shoe that murdering rotten club into absolutely everything?

[@spinalobifida]

I would tell some people that you can go faster than a bus. Of course they don't believe me until i tell them if you run from the back to the front as the bus moves forward, then you are going faster

[@SamiVantaa]

yes

[@Stubhose]

Thank you Sir!

[@54spatula]

David could be standing there in a gimp suit and this would still be amazing.

[@CalSprigley]

😂😂

[@johnwilliams3555]

I am baffled by the huge differences between a proton and a neutron supposedly explained by a seemingly similar arrangement of quarks.

[@howfarawayisit]

I cover the inner components of the proton and neutron in the ''Elementary Particles' segment of my 'How small is it' video book. Take a look and let me know if it helped.

[@cheekymonkey3929]

John Williams me too..😂

[@AMTrexler]

I wish you would have been my physics teacher in highschool as well as college.

[@conanthedestroyer7123]

These videos are 10x better than E-TV.

[@eremitehugs7986]

Dr. Butler.... I'm watching the relativity examples of the train model around minute 15...and I'm trying to make my brain assimilate this I think I'm getting it but... I heard an old comedians joke on TV that if you're driving in a car at the speed of light and you turn on the headlights... does anything happen? I'm trying to visualize that scenario and not sure if I get it yet.. for that example can you illustrate how that works?

[@howfarawayisit]

The speed of light is a constant. it does not matter how fast a source for the light might be traveling. People in the car would see the light travel away from them at the speed of light.

[@ThomasJr]

26:04 You're presenting a not so simple reasoning, and the drawing has two lower v's, no v prime is shown. We can deduce which is v', from Pythagoras, but this worsens the difficulty to follow the explanation. You're really blessed to understand this so easily, but most of us struggle to follow if the explanation is not impeccable.

[@howfarawayisit]

The prime is there. It is just masked a bit by the river. You see it more clearly once the figure moves above the river.

[@ThomasJr]

@@howfarawayisit It's true, I noticed that later.

[@Mike_Curtis]

I used to think I was relatively intelligent. Then I watched these videos. 🤯

[@Rehash84]

I used to think I had great choice in shorts. Then I watched these videos.

[@eklim2034]

the person on the train is moving at the speed of sound with respect to observer from galaxy Andromeda

[@midlandsfloorspringslimite1282]

Hi David, I have watched and commented on your videos before as I find them fascinating and will begin by thanking you again. I was talking to my son a few weeks back and from this we have a question you may be able to help us with or at least give us your respected opinion. We were discussing black holes and wondered if our Universe could have been "born" from the remnants of a previous universe that has been sucked into a black hole, we are the other "side" of the singularity so to speak?

[@jatatanglobustead3963]

Hi. I don't see the gravitational wave update you mentioned. Where is it? Thanks.

[@howfarawayisit]

+Jatatan Globustead I'm a few months away from having it done.

[@jatatanglobustead3963]

David Butler Thanks

[@2liter8]

Interesting but I want to know about the background music, somehow helping the mental process in deep thinking. How does that work? Is it something like a white noise calming effect?

[@jonapleseed6248]

in the video you state that the speed of sound is 1236km/hr, however the next part is about the airplane breaking the sound barrier in 1947 but you stated that he was going 1100km/hr?

[@howfarawayisit]

+Jon Apleseed Good catch. The speed of sound in air is very sensitive to the temperature of the air. 15 degrees Centigrade at sea level gives us 1236 km/hr. But at 9000 meters, where a plan would travel, the temperature drops to -34 degrees and the speed of sound drops accordingly to around 1100 km/hr.

[@jonapleseed6248]

ty i figured it had to do with altitude but i didnt think about temperature. So here is my next question. If stars form from hydrogen gas and when they are undergoing fusion and once all the hydrogen is gone it fuses the helium into to carbon and oxygen and so forth, when the star dies and explodes then how can another star form from the nebula that it leaves behind? If it already used up all its hydrogen where is the next stars hydrogen coming from?

[@howfarawayisit]

Vast hydrogen clouds still fill star forming regions. The great Orion molecular cloud is one of millions of examples. The elements from exploding stars mix with this gas and become a part of the second generation stars created once the hydrogen clouds start to collapse.

[@robthomas221173]

Can you tell me what causes the photon to turn at the end of a wave length? Why does it travel in a wave, surely a straight line would be more economic?

[@stuboyd1194]

Scientists have accelerated a particle to 299,792,457.9964 m/s. This is 3.6 mm per second less than the speed of light 299,792,458 m/s.

[@T1000-s4j]

What's your point?

[@deathsheadknight2137]

thanks for saying so

[@badbadballz]

You have a nice backyard

[@EtcEtcAndEtc]

@Dupa Essex maybe you need to relax

[@ThomasHaberkorn]

nice dubbing

[@dibaldgyfm9933]

Thanks! Fizeau's cogwheel had 720 teeth and could rotate several hundred times per second. Wikipedia: Spinning the cogwheel at 3, 5 and 7 times this basic rotation rate also resulted in eclipsing of the reflected light by the cogwheel teeth next in line.//endquote// The way he counted this is interesting in itself. Furthermore it is (of course) difficult to see when the light becomes blocked; the beam becomes weaker, not null, perhaps because of the half-mirror? Wikipedia: It was difficult for Fizeau to visually estimate the intensity minimum of the light being blocked by the adjacent teeth,[4] and his value for light's speed was about 5% too high.

[@jorgensenmj]

At 6:30 you said "the closer the molecules are to each other the slower the movement". I really wish you would explain that a little more. I have always been taught that higher density materials transmit sound faster.

[@howfarawayisit]

You bring up a good point. Your assumption is correct. The formula is indeed misleading in this area. The denser the medium the faster the speed is factored into the constant K. For example, K is much larger for water over air in large part because the density of water is larger than the density of air. But once we have K so measured, a change in density will have the effect shown in the equation.

[@thesciencethatilove8959]

can someone tell me from which album this background music is taken?

[@ThomasJr]

28:27 You assigned arbitrary values to t_a and t_b? Can these times assume any values or is there an equation that relates the two? For example, could t_a=20 and t_b=10? I guess not cause then the V of the river would be complex. As long as t_a

[@lezlezman1843]

You're hurting my brain!

[@jatatanglobustead3963]

Typo Report -At 10:40 Galilaen to Galilean -At 20:38 "Synch" to "sync" Good job the amount of typos are decreasing

[@howfarawayisit]

got it.

[@tompetrie1676]

That is the William Tell Overture

[@philipwebb960]

And Beethoven's 7th Symphony.