Celsius never devised nor used the scale that now bears his name.

Veritasium is now on Patreon: http://patreon.com/veritasium

Special thanks to Michael Stevens of Vsauce! http://youtube.com/vsauce1

More info about Celsius and temperature scales: http://wke.lt/w/s/2I6Nu

References for this video:

A History of the Thermometer and its uses in Meteorology by W. E. Knowles Middleton

Absolute Zero and the Conquest of Cold by Tom Shachtman

The Science of Measurement, A Historical Survey by Herbert Arthur Klein

Lehrbuch der Chemie by Jöns Jakob Berzelius

Special Thanks to the Uppsala University Museum
I filmed this in Uppsala in the summer of 2012! So I've been thinking about this idea for a very long time. I'm glad to finally have it out there in the world.

We have just seen the first image of a black hole, the supermassive black hole in the galaxy M87 with a mass 6.5 billion times that of our sun. But what is that image really showing us?

This is an awesome paper on the topic by J.P. Luminet:
Image of a spherical black hole with thin accretion disk
Astronomy and Astrophysics, vol. 75, no. 1-2, May 1979, p. 228-235
https://ve42.co/luminet

Using my every day intuition I wondered: will we see the "shadow" of the black hole even if we're looking edge on at the accretion disk? The answer is yes because the black hole warps space-time, so even if we wouldn't normally be able to see the back of the accretion disk, we can in this case because its light is bent up and over the black hole. Similarly we can see light from the bottom of the back of the accretion disk because it's bent under the bottom of the black hole. Plus there are additional images from light that does a half turn around the black hole leading to the inner rings.

What about the black hole "shadow" itself? Well initially I thought it can't be an image of the event horizon because it's so much bigger (2.6 times bigger). But if you trace back the rays, you find that for every point in the shadow, there is a corresponding ray that traces back to the event horizon. So in fact from our one observing location, we see all sides of the event horizon simultaneously! In fact infinitely many of these images, accounting for the virtually infinite number of times a photon can orbit the black hole before falling in. The edge of the shadow is due to the photon sphere - the radius at which light goes around in closed orbits. If a light ray coming in at an oblique angle just skims the photon sphere and then travels on to our telescopes, that is the closest 'impact parameter' possible, and it occurs at sqrt(27)/2*r_s

Huge thanks to:
Prof. Geraint Lewis
University of Sydney https://ve42.co/gfl
Like him, I'm hoping (predicting?) we'll see some moving images of black holes tomorrow

Prof. Rana Adhikari
Caltech https://ve42.co/Rana

Riccardo Antonelli - for excellent images of black holes, simulations and ray-tracing code, check out:
https://ve42.co/rantonels

The Event Horizon Telescope Collaboration
Check out their resources and get your local link for the livestream here: https://ve42.co/EHT

Special thanks to Patreon supporters:
Donal Botkin, Michael Krugman, Ron Neal, Stan Presolski, Terrance Shepherd, Penward Rhyme

Filming by Raquel Nuno
Animation by Maria Raykova

Mosquitoes are attracted to me and it's likely due to my genes.
This video is sponsored by 23andMe https://23andme.com/veritasium
Huge thanks to Prof. Immo Hansen and team: http://ve42.co/hansen

References:
Genome Wide Association Study for self-reported mosquito attractiveness:
http://ve42.co/MossieGWAS

The twin study showing correlated attractiveness is stronger for identical twins:
http://ve42.co/MossieTwins

Some things we know make mosquitoes more attracted to you:
Exercising, higher metabolism, higher body temperature, more body odor, being pregnant, type O blood, infrequent bathing, lactic acid, ammonia, acetone.

There are a number of folk remedies people believe protect them from mosquito bites like drinking alcohol, eating garlic, or taking vitamin B. These do not appear to provide any benefit in lab studies and in fact drinking alcohol is associated with increased mosquito activity because it causes blood vessels near the surface of the skin to dilate.

And apparently some of your attractiveness to mosquitos is simply genetic. This may be mediated through your immune system, which is what a lot of the genes identified were associated with.

Molecular models are microSnatoms: http://snatoms.com

Filming in New Mexico by Raquel Nuno
Animations by Jacqui Robertson

The opinions and conclusions drawn in this video are those of Veritasium and not 23andMe.

Veritasium is a channel of science and engineering videos featuring experiments, expert interviews, cool demos, and discussions with the public about everything science.
Clips featured in this video:
Trees are Freaking Awesome - http://bit.ly/TFilQ8
Gyroscopic Precession - http://bit.ly/U4e8HQ
Can We Go The Speed of Light? (Principle of Relativity) - http://bit.ly/X1BlXZ
Where Does The Sun Get Its Energy? - http://bit.ly/125jbeM
Where Do Trees Get Their Mass? - http://bit.ly/11AA817
What Is A Candle Flame Made Of? - http://bit.ly/Q3enCb
Levitating Barbecue (Electromagnetic Induction) - http://bit.ly/SWgOWh
Imploding Drum - http://bit.ly/125jG8B
Microwave Grape Plasma - http://bit.ly/QkCwUt
Spinning Tube Trick - http://bit.ly/Va43Z6
Spinning Disk Trick - http://bit.ly/14MSKsT
Why Do You Make People Look Stupid? - http://bit.ly/12Fmlpl
Awesome HD Slinky Slow-Mo - http://bit.ly/TRa4sE
Subscribe to Veritasium - http://bit.ly/YSWpWm

Drive along with the NASA’s Opportunity Mars rover and hear the voices of scientists and engineers behind the mission. Designed to run for 90 days, the exploration spanned more than 15 years from 2004 to 2019. Along the way, it discovered definitive proof of liquid water on ancient Mars and set the off-world driving record. For more information on the Mars Exploration Rovers and all of NASA’s Mars missions, visit mars.nasa.gov.

Credit: NASA/JPL-Caltech

¡Acompaña las divertidas aventuras de Minnie y sus amigos!
Ep. 16: Un conejito mágico
Ep. 17: Un tiempo de locos
Ep. 18: Caos Mecánico
Ep. 19: Canguros y Cerditos
Ep. 20: Minnie y la locura de la reforma

Suscríbete al canal de Disney Junior Youtube Oficial http://bit.ly/1lZqZIe.

¿Quieres que tu hij@ se divierta con sus personajes favoritos? ¡Hazte con la

While Apollo placed the first steps on the Moon, Artemis opens the door for humanity to sustainably work and live on another world for the first time. Using the lunar surface as a proving ground for living on Mars, this next chapter in exploration will forever establish our presence in the stars. ✨

We are returning to the Moon – to stay – and this is how we are going!

Actress Kelly Marie Tran of “Star Wars: The Rise of Skywalker” lent her voice to this project.

¡Acompaña las divertidas aventuras de Minnie y sus amigos!
- Ep. 26: Minnie y Daisy están viendo su programa favorito, cuando empiezan a tener problemas con la antena.

- Ep. 27: Minnie y Daisy tiene que bañar a la pequeña elefante estrella de la feria, pero las cosas se complicarán.

- Ep. 28: A Gilbert no parece querer adoptarlo nadie, aunque Minnie y Daisy tratan de animarle.

- Ep. 29: Minnie y Daisy van al campo con las mini-exploradoras, pero tendrán algunos problemas con los habitantes del bosque.

- Ep. 30: Daisy tiene un nuevo despertador que parece perfecto, hasta que empieza a hacer de las suyas.

Suscríbete al canal de Disney Junior Youtube Oficial http://bit.ly/1lZqZIe.

¿Quieres que tu hij@ se divierta con sus personajes favoritos? ¡Hazte con la

Evidence Facebook's revenue is based on fake likes.
My first vid on the problem with Facebook: http://bit.ly/1dXudqY
I know first-hand that Facebook's advertising model is deeply flawed. When I paid to promote my page I gained 80,000 followers in developing countries who didn't care about Veritasium (but I wasn't aware of this at the time). They drove my reach and engagement numbers down, basically rendering the page useless. I am not the only one who has experienced this. Rory Cellan-Jones had the same luck with Virtual Bagel: http://www.bbc.co.uk/news/technology-18819338

The US Department of State spent $630,000 to acquire 2 million page likes and then realized only 2% were engaged. http://wapo.st/1glcyZo

I thought I would demonstrate that the same thing is still happening now by creating Virtual Cat (http://www.facebook.com/MyVirtualCat). I was surprised to discover something worse - false likes are coming from everywhere, including Canada, the US, the UK, and Australia. So even those carefully targeting their campaigns are likely being duped into spending real money on fake followers. Then when they try to reach their followers they have to pay again.

And it's possible to be a victim of fake likes without even advertising. Pages that end up on Facebook's "International Suggested Pages" are also easy targets for click-farms seeking to diversify their likes. http://tnw.co/NsflrC

Thanks to Henry, Grey, and Nessy for feedback on earlier drafts of this video.

This video is about TU ESTAS AQUI - JESUS ADRIAN ROMERO FT. MARCELA GANDARA - PISTA (KARAOKE)

https://www.paypal.com/donate/?token=W00LAy6mMt7CxoZZd2KeiULlwN4iwdinhYltfd162hwr8Tql6kSse5C6gV8qhCFxkg_YD0&country.x=CA&locale.x=CA cualquier donacion a este ministerio sera un abendicion ...y juntos podamos seguir con esta gran labor de seguir formando muchos mas musicos para el servicio de su obra https://www.paypal.com/donate/?token=W00LAy6mMt7CxoZZd2KeiULlwN4iwdinhYltfd162hwr8Tql6kSse5C6gV8qhCFxkg_YD0&country.x=CA&locale.x=CA

Descarga esta producción musical - https://itunes.apple.com/us/al....bum/jesus-siempre-ll

Lleva la musica a la puerta de tu hogar - http://www.amazon.com/shops/samuelhernandezmusic

facebook - http://www.facebook.com/samuelhernandez
twitter & periscope - http://www.twitter.com/hernandezsamuel
instagram - http://www.instagram.com/hernandezsamuel
youtube channel - http://www.youtube.com/samuelhernandezcanal

Esta producción de Jesús siempre llega a tiempo a bendecido a miles de personas, cientos han sido sanos y salvos atraves de esta producción siendo usada por Dios. Por otra parte cambió la musica cristiana para siempre logrando nominaciones a Grammy Latino y Billboards y convirtiéndose en la primera producción cristiana en colocarse en la posición #1 tanto a nivel cristiano como secular con el tema "Levanto mis manos". Dicha alabanza se ha convertido en un himno a nivel mundial que ha bendecido a millones de personas, porque Jesús no se adelanta ni se atrasa, Jesús siempre llega a tiempo!!

¡Es el cumpleaños de Minnie! Mickey y sus amigos preparan una fiesta sorpresa con globos y van a contar con una ayuda muy especial.

Suscríbete a nuestro canal: http://bit.ly/1lZqZIe
Más novedades en el canal oficial de Facebook de Disney Junior: http://on.fb.me/1arQif0

Levanto mis manos de Samuel Hernández. Musica cristiana de adoración.
Canción con unción y ministración del Espiritu Santo. !!Compartela!!
Para que sea de bendición a otros.
Cuando levanto mis manos mis cargas se van. Que bueno es nuestro Dios.
FACEBOOK : https://www.facebook.com/music....acristianaconletra?r
https://es-es.facebook.com/CCI.Huelva
Twitter: https://twitter.com/ccihuelva
EL BLOG DE LA MUSICA :http://musicacristianaconletra.blogspot.com.es/
CANCION DISPONIBLE EN ITUNES

Siento una angustia en mi corazón...
una tristeza que no es normal
siento tan lejos tu amor Señor
dime adonde estas...
dime adonde estas...
a que hora Señor
no te puedo allar

(1) Reconozco Señor peque
y reconozco Señor falle
la oscuridad me a visto llorar
el silencio también
me ah oído a mi
escuchame Señor
y perdoname, perdoname

Coro:
Tal como soy
vengo hasta a ti
con la esperanza y también la fe
de que tu Señor me perdonaras
de que tu Señor me perdonaras

(1)
coro(x1)

Grace se niega a que Nancy deje a los niños pequeños entrar en su casa de muñecas. Así que Nancy deberá decidir entre quien cree que son sus amigos y sus amigos de verdad.

Suscríbete al canal de Disney Junior Youtube Oficial http://bit.ly/1lZqZIe.

¿Quieres que tu hij@ se divierta con sus personajes favoritos?
¡Hazte con la

Creo que toda persona que habla del mensaje del Evangelio es soldado de Cristo. Les anímo a visitar mi sitio: http://www.blogger.com/profile..../0842037997471047394

De tu boca sale aliento
Que mi alma necesita
En tu palabra hay poder
Que trae vida a mis huesos

Jesús tu nombre es el verbo de aliento
Jesús tu nombre es el agua de vida
De tu boca sale aliento
Que mi alma necesita

Jesús tu nombre es el verbo de aliento
Jesús tu nombre es el agua de vida
Oh Jesús tu nombre es mi pan.

Tú hablas y el sordo oye
El ciego ve al oír tu voz
Grande es tu poder
Grande es tu poder, Jesús

Tú hablas y el cojo anda
Con tu poder el mudo habla
Habla sobre mi
Habla sobre mí, Jesús

Era ciego y ahora puedo ver
Sordo fui y hoy te escucho
Habla sobre mí, Jesús

Preso fui y hoy libre soy
Perdido estaba, mas hoy tu hijo soy
Habla sobre mí, Jesús
Habla sobre mi
Habla sobre mí, Jesús

Habla sobre mi
Habla sobre mi
Habla sobre mi

Habla sobre mi
Habla sobre mi
Habla sobre mí, Jesús

Era ciego y ahora puedo ver
Sordo fui y hoy te escucho
Habla sobre mí, Jesús

Preso fui y hoy libre soy
Perdido estaba, mas hoy tu hijo soy
Habla sobre mí, Jesús
Habla sobre mi
Habla sobre mí, Jesús

Cuando creas que todo pinta mal y que las cosas no marchan como te gustaría… ¡Añade la elegancia y todo cambiará! Con Fancy Nancy Clancy y sus amigos, todo lo que parece aburrido, puede cambiar al instante: sólo hay que dejar volar la imaginación. Oh là là!

Fancy Nancy Clancy, una nueva serie. Estreno el 7 de enero a las 20:30 en Disney Junior.

Suscríbete al canal de Disney Junior Youtube Oficial http://bit.ly/1lZqZIe.

¿Quieres que tu hij@ se divierta con sus personajes favoritos? ¡Hazte con la