The Biggest Ideas in the Universe | 12. Scale

The Biggest Ideas in the Universe is a series of videos where I talk informally about some of the fundamental concepts that help us understand our natural world. Exceedingly casual, not overly polished, and meant for absolutely everybody.

This is Idea #12, "Scale." For something more down-to-Earth than the last couple of lectures, we think about why things have the size they do. This is a rich topic so we don't get very far into it, we'll have to return later!

#science #physics #ideas #universe #learning #cosmology #philosophy #quantum #scaling

[seancarroll]

Erratum: around 33:00 I misread "70" in my notes as "76." The mass of the Milky Way is about 10^70 times the mass of the proton.

[alex_madeira]

It’s very rare that someone with such seemingly ineffable range and scope is combined with the ability to communicate so clearly and cogently. There’s nothing like this series available anywhere else - I look forward to each episode. I suspect people will be watching this series for decades to come and it might just inspire a new generation. Feynman and Sagan did this through their medium of the day. This is up there in my opinion.

[vlrath]

I have never followed a video series so passionately as this. Not even the Mindscape podcasts (the one on the meaning of life was awesome though). This is what I had been looking for years, sporadically finding pieces here and there, but never as comprehensively explained from the concepts point of view. Hopefully this will continue on for more episodes.

Thank you to Prof Carroll so much for taking the time to do this.

[FirstRisingSouI]

"You can smash airplanes together all you want."
–Sean Carroll, 2020

[johnbroadhead]

Thank you Sean Carroll for your amazing series of videos. I grew up a child of the Apollo rockets and was 11 when "we" first stepped on the moon. I have been an avid watcher of science and rocketry since. You make these topics accessible and I find your dedication extremely admirable. Makes me feel like a slug! Thank you again. Your volume of quality output is extremely impressive as well!

[Psnym]

I love this series. These videos are going to be staple for a long, long time

[bmoneybby]

My favorite floating half torso on the internet. Yee!

[obsoleteboomermobileobsole]

My favorite thing about Sean Carrol is his objective viewpoints, and his understanding of philosophy that goes in tandem with his scientific knowledge

[Quantumpencil]

Professor Carroll, I really love what you're doing with this series and for physics education more generally. I ended up giving up on physics in undergrad (in favor of math) due to a combination of personal issues and poor preparedness (poor rural background, went to ivy league school, was arrogant and sabotaged myself basically) but ended up approaching physics again later in life and finding joy in it.
These videos have been invaluable to me, and helped me clarify so much conceptual confusion I carried from undergrad/that common books on the relevant subjects often ignore in favor of mathematical formalism. You're an incredible teacher and your students are quite lucky. I for one am eagerly awaiting your upcoming Quantum Mechanics text, thankfully I have Spactime & Geometry's new printing to keep me occupied until then.

[ScotClose]

For a preview of scale as it relates to biology, see Sean's interview with Geoffrey West. Very good episode!

[kjrunia]

29:25 'Chemists – bless their hearts – care about the real world (...)' That properly cracked me up.

[esperancaemisterio]

A new video from this series! Thanks a lot! Stopping everything else and starting to watch! =)

[trxe]

I literally watch these videos 2 or 3 times before moving on to the Q&A and then watching those twice. Consequently I am still on interactions lol, this stuff is gold. Maybe my favorite series of anything ever.

[jeffbass]

Wow! I wasn't expecting it but I think this was the best episode yet. So many ideas all coming together. If there is this "minimum size" for particles, then why do people talk about elementary particles as point particles? Also, what is the relationship between Compton wavelength and de Broglie wavelength?

[markconrad]

But Sean, Antman has a compton wavelength modulator built into his suit! Also Pym particles...hello? Maybe you should do more research before you discredit Dr. Henry Pym...smh

[robertshirley]

According to this scaling, the speed of light is constant and equal to one, because roughly one second is equal to 10^15 ev ^-1, and the distance of 300, 000, 000 meter that it covers in one second is roughly equal to 10^15 ev^-1, therefore c=1 and constant, since c=distance/seconds. this means, in terms of their ev value, the time unit and distance unit(if we think of 300, 000, 000 as one unit of distance) change simultaniously for the light and therefore light does not feel passage of time!(light is stuck in time because it moves exactly with time’s speed and time’s speed is one second per second!

[vinm]

Milky Way must be 10^70, NOT 10^76.
Because roughly there are 100 billion stars in the Galaxy (actually 86 billion)
and 100 billion galaxies in the Universe. (actually 125 billion)
So protons in the Universe must be 10^11 larger than in a galaxy. (roughly)
Therefore :-
Miky Way 10^70 and Universe 10^82, would make more sense.

[geekysuavo]

Sean: writes Avogadro's number to *one* significant figure, rounds to 1e24
Me: dies internally
Sean: "Chemists, bless their hearts"
Me: dies externally 😅

[narfwhals]

How do i get the same results for scale when my energy cutoff gave me a different value for alpha? Is my compton wavelength also different?

[NerdyRodent]

I think the scale in my mind just broke...