Thank you so much for hosting me! Such a fun collab on such a special maths channel! Thanks for watching!!

@drpeyam

Жыл бұрын

Awwww you’re so very welcome 🤗

Every time a mathematician collaborates with a physicist, the world becomes a better place.

Nice! Would use a more pronounced dot for the derivative though. Thought it was some dirt on my screen for half the video.

Very nice indeed! Great idea to Introduce such an interesting lecturer!

@zhelyo_physics

Жыл бұрын

Thank you very much! Glad you enjoyed it!

In the gravitational potential energy term, why isn't R squared in the denominator? Is it due to the fact that we equate gravitational energy as the work done by the gravitational force (with R^2 in the denominator) over the distance R?

@richardthomas3577

Жыл бұрын

R squared in denominator is for force (Newton's force law for gravity). You can just check units to see that this is correct for gravitational potential energy.

@mewsicman9541

Жыл бұрын

Yes then integrate it from 0 to ♾️

@zhelyo_physics

Жыл бұрын

Excellent question! Newtonian gravity gives us the gravitational force being proportional to 1/R^2. GPE is the integral of this with respect to distance (this is gives us work done, i.e. change of energy) and hence the factor of 1/R. Hope this helps! : )

@Bani5710

Жыл бұрын

Makes sense, thanks! Great video :)

Awesome

I haven't done Physics Olympiads before, but if I understood this video correctly, the assumptions are: 1. The universe is Newtonian. Ignore relativistic and quantum effects. 2. The universe is spherical. Am I right?

@zhelyo_physics

Жыл бұрын

Fantastic question! 1. Yes. I actually find it amazing that you get a non static universe even in the classical world of Newtonian gravity and Euclidian space. There is a standard derivation in terms of general relativity where the cosmological constant arises naturally. This would only appear in the classical derivation if you add in an extra term in the potential for dark energy increasing in distance. 2. Actually no. We are exploiting Gauss's Law for gravity (spherical symmetry) by considering a homogenous spherical blob. By Gauss's Law all contributions from the outer shell and beyond would cancel out assuming homogeneity. Hope this helps, excellent question!

1/137.0013

@zhelyo_physics

Жыл бұрын

One of my favourite constants! Need to do a video on the fine structure constant.

Cosmology is so fun when you aren’t in a class with a grade lol

Who said the Universe is a sphere? The Universe is expanding to each of the blackholes, entering the the wormhole to come out, in the past, at the only whitehole that exists, the Big Bang! So, the Universe is torus.

recall this non-Euclidean theorem...Formulae of Bolyai-Lobachevsky........tan(psi/2) = e^(-d/k)......let d = R(t) ....and let k = K......in hyperbolic geometry the area of any triangle is at most ........ 3.14 * k^2....see Euclidean and Non-Euclidean geometry .... Marvin Jay Greenberg ....p323

I followed everything except the mass ¨m" which was not defined.

Why don't physicists start by defining what they mean by "Universe"?