Can you ask professor to explain the "flat" universe bit? I didn't understand most of what he was saying, but that part wasn't logical at all to me.

@@conanobrien1 curvature of space can be measured by measuring angles. Say you have laser beam and direct it with mirrors in such a way that the beam makes a complete triangle. In a flat space the sum of angles in such triangle would be 180 degrees, same what is used in Euclidean geometry. If the space has a negative or positive curvature, the sum of the angles in such triangle could be larger or smaller than 180 degrees

Have you changed microphones for recording or changed compressor, audio sound to polished and weird. Ed´s voice sounds different.

@@jormam69 Would that be the same (similar) as when they say big objects (black holes or galaxies) curve space-time?

We need more Prof Copeland on the whiteboard.

It’s the opposite of political interviews, when the journalists always seem to be half asleep and never ask the most obvious questions.

I do like his delivery

Ye, mine too.

His disposition is just so different from the image I have in my mind when someone says "physics professor," and it is wonderful.

yes

All the presenters are excellent, but i must say he is my favorite too (Tied with Sir Martyn I suppose)

Yes, they love to vibrate when they purr.

@@jacobscrackers98 THIS! YES! 🤣😂🤣😅

That’s brilliant!

In Universe Res?

If it's within an eternal inflation model, call it the "quick stop."

Naaah, I suggest The Blow Out.

@@aretorta prolapsed singularity?

I'm just going to give a second plug for my suggestion "The Cold Open", like the pre-credit scene in movies or shows. ^_^

If something hasn't yet inflated it must be a period of flacidity? ;)

Without a doubt. Ed is just one big cuddly hug of physics.

I'll nominate "The Big Breath", such as one would take before inflating a balloon. It would make the creationists happy and maybe they'd shut up for awhile.

is there a name for the sound you make right before you blow up a balloon? like ya know, the gulp of air you take as you lean back slightly and tilt your head up in preparation for blowing it up. Insufflation is the only word that comes to mind. though that's an imperfect fit.

You're got roughly a one hour in 60 years chance of that happening 😅

HBB is not equal to BB. BB was BEFORE inflation, HBB is just a new fancy term for saying "after inflation".

@@schawo2 Hm. I must have misinterpreted what the video was saying. I'll give it another look. Thanks.

It's because the whole thing is still conjecture and we really don't know whether there even was a beginning

Me 2

Agree

Thanks for your loyalty.

​@@sixtysymbols 1) When was space-time born? 2) Where the initial insane amount of Potential Energy comes from? 3) If mass is created by interaction with Higgs and that interaction bends space then is gravity the interaction with Higgs?

FreeCourseWare from KZfaq here in the states has been incredible, with that said your channel and specific content is the cherry on top. Thank you sincerely Sixty Symbols I always recommend the channel to others. Sincerely.

@@sixtysymbols So he says the system of equations is nonlinear 21:00, right? So I assume whatever system of nonlinear equations he is talking about are PDEs (partial differential equations) or even combinations of PDEs and functional and integral equations. That's what we differential algebraists work on. We work on finding exact solutions. I own three large handbooks by Soviet authors on differential equationd, the largest of which is the 2nd edition of "Handbook of Nonlinear Partial Differential Equations" by Andrei D Polyanin and Valentin F Zaitsev, followed by 2nd edition of "Handbook of Linear Partial Differential Equations for Engineers and Scientists" by Andrei D Polyanin and Vladimir E Nazaikinskii, and 2nd edition of "Handbook of Exact Solutions for Ordinary Differential Equations". The ODE book is especially full of exact solutions of different types of nonlinear ODEs. All of the solutions are obtained by looking at differential symmetries of the ODEs. I still do not understand quite how they are getting these symmetries. The ODE book, but especially the nonlinear PDE book, have excellent sections on the general theory of differential symmetries. But, I cannot match that general theory up with the many many examples of exact solutions they find. I would really LOVE to sit down with somebody to help me work that out together. Nevertheless, one very general pattern that arises from these solutions is that ALL of them can be expressed, parametrically, by a finite tower of intermediate variables, where one variable in this tower satisfies a linear ODE over the differential ring generated by the variable below it. i.e. given G(x,y,dy/dx)=0 there exists a tower v1, v2, v3,..., v(m), t and another tower w1, w2, w3,..., w(n), t and some final common variable, t, below it, such that x satisfies a linear ODE w.r.t. t over Z{v1} = differential ring generated by v1=v1(t) over the integers, Z, with derivation D such that Dt=1, and v1 satisfies a linear ODE w.r.t. t over Z{v2} and so on until v(m) satisfies linear ODE over Z[t]. Similarly, y satisfies a linear ODE w.r.t. t over Z{w1} = differential ring generated by w1=w1(t) over the integers, Z, with derivation D such that Dt=1, and w1 satisfies a linear ODE w.r.t. t over Z{w2} and so on until w(n) satisfies linear ODE over Z[t].

When we let physicists name things, we get “quarks” which have “flavors” like “charm” and “strange”

@@AdamKlingenberger They need a branding manager, stat. =:o}

in all fairness its not a very intuitive concept and it can be difficult to explain to people that you might call a layperson. I get the ideas needed and its still sometimes hard to wrap my mind around the idea of it.

@@1104Tea Yeah, I've tried to explain large scale spatial curvature to a few different people with mixed success. The classic analogy people always use is the surface of the earth, but extending to 3 dimensions is tricky. One guy didn't even believe me when I said parallel trajectories on earth come together. Plus there's the distinction between intrinsic and extrinsic curvature...

I think i got a better appreciation of "the metric of spacetime" by playing around with simpler metrics. With chess distance one diagonal step has the same length as one axis-aligned step, meaning that a circle (i.e. constant distance from the center) has the shape of a square. With manhattan/taxicab distance one diagonal step is two axis-aligned steps, meaning a circle has the shape of a rhombus. Understanding that the very notion of "distance" depends on how/what we measure felt like a revelation. But curvature is about direction rather than distance (i think). I still don't really understand what the heck intrinsic curvature means. Maybe the best analogy is still the Asteroids video game. It takes place on a flat surface but the edges are connected making it topologically a torus 🤷‍♂️

@@mxlexrd Try going with "Stand on the equator; we'll all walk due north on parallel paths. And it then gets crowded by the time you reach Canada." ;)

It's a really simple concept. Just tell them that 'flat' means all lines on a 3D grid are parallel and straight!

Glad you enjoyed it!

14:53 sounds especially like adobe enhanced speech, the way his voice drops down very artificially

Yeah! I was looking for this. Sounds like it been pitched down or he's got a cold or something

I'm not complaining or trying to be rude!

Glad I wasn't alone in this thought. Feels like there may be distortion from any audio level normalization is my guess, since Ed isn't wearing a microphone and his distance from the mic probably isn't constant

Mic broke, so we had to fix up the camera audio the best we could

The idea of inflation (slow roll and eternal) has been around since the 1980's.