#5minphysics 

There was a cartoonist from Australia talking on the Coast to Coast AM show with George Noory. He had a theory that the Earth had weaker gravity, and was smaller in size 65 million years ago. He said that a Tyrannosaurs Rex had a head that weighed about the same as a motorcycle and that in todays gravity it would snap off the creatures neck, so gravity had to be less back then.

That's why all the animals living duiring subsequent ice ages were so big, compared to their modern counterparts - mammonth to elephant, wooly rhino to African rhino, cave bear to bear, Irish elk to deer, etc. Heat is produced by body mass (thus volume), but is dissipated through skin (thus surface). If a mammoth was twice as big, as an elephant, it was able to conserve its heat twice as efficiently (R^3/R^2=8/4=R=2) in extremely cold climate.

At some point in my growing understanding of the universe, my feelings changed when I look up at the starred night sky. I used to glance at it as nonchalantly as I gazed at cobwebs on my ceiling - "ah, there it is and I can’t reach it." Now, when a look up, I’m overwhelmed by a strange sense of sadness, loneliness, futility, all compounded by the reality of not knowing and for what purpose it’s all there. I think one of the things that prevents people from “believing” in things like evolution or the Big Bang is that the size of stars and galaxies, atoms and particles, and lengths of time that are talked about are simply incomprehensible to normal people - our reference frames are vastly under ranged. When I stand outside, I can estimate what is 10 feet away, maybe even 100. When I close my eyes, I can imagine a place one mile away, maybe 10; some truck drivers might imagine 100 miles away. The same goes for time, I can imagine a year ago, or 10. But a million? A billion? A trillion? Even these words work against us, they all have the same number of letters and syllables but one is 1000 times larger and another is 1000 times larger than that. These dimensions of time, space and size are just completely incomprehensible. We try to reconcile this with simulations. If a golf ball were the nucleus of a hydrogen atom, the electron cloud would be about .8 miles away. But that only works if you can imagine or visualize a mile and it gets worse with time. The range of our consciousness is just too narrow. How can we expect people to understand these things when they can only visualize a grain of salt to a mile and from a split second to a lifetime?

Wow! Physics is such a powerful tool to break things to the most fundamental principles and to reason up from there.

I can not listen to any one else I really think you are the top dog in this field and without sounding to worshippy I just love what you have done with dawkins and the hitch in that field hehe as a musician all i can say is keep on rockin in the free world ,peace

1:53 that applies to illustrators as well. Breaking things down into primitive forms for easier construction

First again! You are the man and thank you for explaining physics in a manner that we can understand and realize that it's not that hard to a point. It's not too late to learn.

You're the teacher I always wanted but never had. I could have been the next Einstein!

Thanks. So brightly explained and why physics is a short cut to pragmatic understanding. Greetings from South America.

Wow actually that's very amazing

Beautiful.Just beautiful. So glad I studied Physics at Uni.

Thanks again from Ireland Lawrence, Great work.

I knew you were gonna do it! And you did! You did the cow! That is so great, and funny! Thank you, I needed something like that for a little relief, in these days.

I’ve watched the Noam Chomsky interview probably five times...Incredibly interesting. The volume of knowledge and deft ability to apply such nuanced context is a special treat to behold. Lawerence...Please continue to interview exceptional people from all disciplines

Good work professor,waiting for next.

Greetings Professor. This is a great series of episodes, with just the right amount of math, so even non-physicists like me can understand core topics in more depth. Maybe just need to rename the series to #10minphysics. Thank you and keep up with your work!

Brilliant!! Thanks again Lawrence. I will never look at a Cow quite the same ever again ;-).

So what you're trying to tell me... is that in physics, it's valid to view the spherical Earth as cow-shaped? Thus ending the age old question, what is the shape of the Earth.

Good stuff

Brilliant explanation

8:02 "That looks a lot more like a cow" 😂 Amazing ❤️

Nice!

I couldn't help but draw parallels from your past 5 minute physics videos on the energy of empty space, when you touched on the pressure of a cows skin increases non linearly to that of the area, this is what you were emphasizing in your physics of an expanding universe video when space itself expands, but I think you emphasized it much better; even if unintentional with our dairy friends. Excellent video, stay safe and please continue putting these out. I love them and it's going to greatly help my students while we're 'distant learning'.

So good 👍

Reminds me of Haldane's "On Being the Right Size"

You always say some things you haven't said before. That's why I watch...

Needs a lot more views

A geneticist would manipulate the genes/organs involved in lactation (which we have essentially accomplished via artificial selection), increasing their production/size just below that physical cutoff.

Lawrence, I have been consuming your videos / interviews /debates / books and anything I can find on the internet and bookstore (+ the movie The Unbelievers) since I first saw you in Hyperspace mini series. You have been always engaging. If I might say, I liked the same material better in your talk at NECSS (ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-h9FurAf4C4g.html). Would you consider using a whiteboard for this series. I look forward to more 5 min physics videos and wish you the best.

🧙‍♂️One ought to be ashamed to make use of the wonders of science embodied in a radio set, the while appreciating them as little as a cow🐮 appreciates the botanic marvels in the plants she munches. "Albert Einstein"

Dr. Krauss: I have a question on an unrelated topic. Your debates on atheism was one of the reasons my atheist beliefs got strengthened. I believe science can or will answer most of “how” questions about universe, e.g., how does a black hole form? But do you think it will ever answer “why” questions? E.g., why does the nature and its laws exist? No matter how much we explore, we can never be satisfied with any answer to “why” questions. Even if god appears and explains why everything exists, the answer cannot satisfy us. So, our pursuit is only to find answers to “why”?

Another nearly "wholly cow!" episode. If you'd added an economist to the mix of experts, could talk about devastation of milking stool manufacturers with monster cows, unless adapted and made step ladders that held milk buckets... used to give my students problem re area: what's the better deal? two 8" pizzas of one 12"? Something they could sink their teeth into...

👍 Dr. Krauss thank you for another great video! So this explains why rocky planets like earth can only be so big (super earths)? Otherwise to get bigger they need to be gas giants like Jupiter, Saturn ect...?

👍🏼

I get it! Although the letters & number thing always throws me off 🥴

The internal pressure of the cow is not proportional to its mass per unit area.

maybe rename the series to 10minphysics :)

is this why atoms are so small compared to the greater universe ? small branes??

And Mother-in-laws!

I live those happy spherical cows. Where can I get a steak?

Dude! Don't have a cow!

Laurence, you're wrong, the pressure remains the same. The rest of your logic is corrupt, too. And I didn't like your book. Sabine talking about nine kinds of nothingness for ten minutes was handier.

It's kind of sad that you have to make a video about high school Physics :(