Nuclear Engineer Reacts to Veritasium 'Entropy - the Most Misunderstood Concept in Physics'

[tylerwillson]

You've completely reshaped my family's understanding of nuclear energy and it's potential to help control climate change. Now we regularly discuss nuclear energy around the dinner table lol! Love seeing your notifications every week! Keep up the good work!

[TylerMusgrave]

I already watched the whole Veritasium video, but I always enjoy your reviews because you always have something interesting to add! Just happy I got here early for once.

[ohno]

I was hoping he'd go over this in the video but there's a really interesting proposed explanation for why entropy was low to begin with. Since entropy is only extremely likely to increase over time, and not guaranteed, you can start with a high-entropy universe and wait for the entropy to suddenly and coincidentally drop by a huge amount. At any given point this is ludicrously unlikely, but since you have infinite time, it's guaranteed to happen eventually. So, if you plot entropy vs time, you actually do get something that looks the same backwards and forwards; eons and eons of high entropy, punctuated by incredibly brief downward spikes.

So, it's worth mentioning that even when the heat death comes it won't necessarily be eternal. We just might have to wait a while.

[mibadada]

This is a great Veritasium video and i love your reaction to it! I always enjoy the new insights you are bringing in from your POV and experience area
I know your focus is physics and engineering but as a math person I would recommend their video on the history of imaginary numbers, it's such a cool topic (they go into less detail on the modern applications of complex numbers, but maybe you would have something to say there? I'd be curious if complex numbers come in to your day to day or the math behind it at all)

[barefootalien]

My favorite way to describe the relationship between the Arrow of Time and Entropy comes from Sean Carroll. As a free bonus, you also get the answer to the question "What happened before the Big Bang?"

Paraphrased, what he says is that in deep space, in the middle of nowhere, there is no preferred direction in space. All directions are equal. This is similar to how, at the end of the universe, there is no preferred direction in time. Indeed, in most of the laws of physics, there's no arrow of time, just as in most of the volume of space, there's no (meaningful) arrow of space.

But on the surface of the Earth, there is most definitely a preferred direction in space: *down.* If you drop an object, it falls _down._ Down is the preferred direction here, because we're in close proximity to a very influential body: Earth itself.

Time is no different. Now, a dozen or so billions of years into the existence of the universe, there is most definitely a preferred direction in time: *future.* Even doing absolutely nothing, you are still moving into the _future_ at a rate of approximately one second per second. The future is the preferred direction _now_ for basically the same reason that the preferred direction _here_ is _down._ We're in close temporal proximity to a very influential _event:_ the Big Bang.

The gravity gradient created by the influential body we live on the surface of means that all else being equal, objects will flow _down_ to the lowest locally available point. The _entropy_ gradient created by the influential _event_ we live nearby means that all else being equal, objects will flow _forward_ into the future.

As for what happened before the Big Bang? That's not even a sensible question to ask. It's like asking "What's further north than the North Pole?" It's not that the answer is just that nothing is further north than the North Pole; it's that that doesn't even make sense to ask that question, because "north" is only defined in terms of our influential body and its gravity gradient and other properties. Similarly, "past" is only defined in terms of the proximity to our influential event and its entropic gradient. As far as we know, _time itself_ was created in the instant of the Big Bang, so what happened before that low-entropy event? That's as meaningless as asking what's north of the North Pole. It's not just "nothing"... it's "undefined".

I don't agree with _everything_ Sean says and believes in... I don't believe in the block universe, for example, nor do I believe that the Arrow of Time is a _purely_ stochastic phenomenon driven purely by entropy. But this is still a powerful way to think about entropy, a powerful analogy... and that entropy and the arrow of time are intimately linked is undeniable.

I hope to live long enough to see us learn what deeper truth underpins and assures that link. I suspect it may have something to do with Dark Energy, or whatever combination of phenomena winds up replacing that nebulous black-box placeholder of a concept that our understanding is currently limited to.

[thesuperdak]

...and this is how the Universe ends:
Not with a bang, or even a whimper.
Entropy is triumphant, and everything is equal --
Equally cold.
Equally dark.
Equally flat.
Equally Dead.
And of all the galaxies, and stars, and planets, and peoples, and monuments, and stories, and songs,
There is...nothing...
To show what had gone on before.

[vettir]

avogadro is per mole, which has a mass of the atomic mass of one formula unit of a material.

[thomasfleming]

I feel like I just learned more in this video than I have in years of watching videos about physics and space. It is easily broken down, and with the second opinion added it really reinforces the memory of the idea or concept. Great work man! Keep it up!

[GregJumpscare]

"I need this on a T-shirt"

Don't we all

[Cracktune]

by far the best channel ive found this year. Keep up the great work, please and thank you

[Yumari-Mai]

It was really nice to watch a Veritasium video with someone fact-checking in real time, I think this adds a lot to the whole experience :)
The thing I missed the most from Veritasium in this one was the formulation of 2nd law of thermodynamics which in fact states that entropy *never decreases*.

It's very important to note that the inequality is "Et1 >= Et0" and not simply "Et1 > Et0", where Et1 is next entropy amount, and Et0 is the current one.
This is required to properly understand the existence of time crystals, among other phenomena.

Overall, though, a great video and a fantastic explanation with some novel insights for me.

[mattpage]

Great video. Veritasium is another great channel for the enquiring mind. My current 4 thought provoking channels, which you are now one, includes Veritasium, PBS Space Time, and Issac Arthur. Have a great day!

[PhotonVideos]

Thank you for your awesome insights into the nuclear field! I had a similar reaction to considering that life is a natural phenomenon and less of a mystery. Maybe sun–worship had it right all along!😅

[roseryvines]

It might be a bit out of your alley, but I suggest the ‘Timelapse of the Future’ by melodysheep. It’s pretty long but it’s quite good!

[Ambutakumm]

I-I- I be popping bottles... Sparkles and Champagne

[notaperson-wxvs]

I love watching your videos, I immediately click when I see one of your videos

[ThatJay]

when i first watched veritasiums entropy video i was on magic mushrooms

[horisontial]

I think it's pretty cool that in the distant past of the early universe the atoms that comprise me was immeasurably close together and some day will be light years apart.

[albertbocek]

I would love to see you react to veritasium spontaneous synchronization. So interesting video. Love your reactions.

[John_Ridley]

@12:15 the way I heard it is * You can't win * You can't break even * You can't get out of the game