Show HN: An Interactive Audio Lesson About the Shape of the Universe | Hacker News Reader

Show HN: An Interactive Audio Lesson About the Shape of the Universe

chrisuehlinger.com

49 pointsUehreka15 comments

Very nice! I really like this kind of teaching :-)

Nitpick: If the model universe is a square that is 100 meters across as said in one of the first lessons, it's area is not 100m2 as stated in one of the next lessons.

Somehow, I just knew a dumb mistake like that was going to make it in. Thanks for the tipoff, I'll record a new voiceover this weekend and edit those bits.

That was fascinating, and very well done. It's not often you see somebody actually creating interactive scripts (and miniature models) of things like particle collisions for a presentation. The availability and the quality of the external links is also highly appreciated (even though sending me to Vsauce might cost me another evening). A couple of suggestions for improvement:

An estimate for how long the lesson will take (on average), best stated up front.

An indicator for where we are in the presentation (like "slide 5 of 18").

A way to pause the audio in the middle of a slide (I just saw you already addressed this one).

On the "Corrections" slide, you mention a fascinating PBS documentary. It would be nice to get a link to that, too (if available).

loved it! just one question : when the universe expanded, why did the size of the spheres, the rocket and the asteroid remain constant? shouldn't they expand too?

So this has to do with something called Dark Energy; I may dedicate a whole lesson to it. On small scales (small meaning the size of galaxies and smaller) Dark Energy isn't strong enough to overcome gravity (or any of the other forces that hold stuff together). However in the void of space where gravity isn't too strong, Dark Energy runs rampant pushing things apart at high speeds.

If I were to do the math on how much Dark Energy there was in my tiny universe, it might actually be the case that the asteroids should've been torn to shreds by the immense amount of Dark Energy. In fact, there used to be an interesting doomsday theory called the Big Rip, which went something like this: If Dark Energy got more and more powerful with time, eventually it would overcome gravity and start pulling apart galaxies, then stars, then molecules, atoms and subatomic particles. This scenario is no longer considered likely, but it's still crazy to think about.

Dark Energy - https://en.wikipedia.org/wiki/Dark_energy

The Big Rip - https://en.wikipedia.org/wiki/Big_Rip

Are you sure that this has to do with Dark Energy? Dark Energy is an unknown form of energy that must appear in Einstein's equation in order to make the universe accelerate at its current rate. Are you saying that:

1. Dark Energy only makes the space near it expand and has little to no effect on faraway regions?

2. Dark Energy is not present in places which has high matter density. Therefore, space in places with high matter density do not expand at the same rate as other regions (which contain Dark energy)?

Wow this is incredible! Super fun :)

Good stuff and cool your from Baltimore & working on a reveal.js project too.

Is there any way to pause?

Unfortunately not at the moment, although you can click the refresh button in the lower right corner to restart a slide if you missed something or mute the presentation audio if you need to.

I'll look into adding a pause button, I'll just need to make sure that certain animations pause if they were synced to the audio.

oh my god the vocal fry

Of all the time and effort that must have went into this, you are complaining about the sound of his voice?

Please don't post dismissive comments to Hacker News.

Voice sounded pro to me.

The voice is perfectly fine. Non-native speaker here - I understood every word; the narration was very pleasant and not annoying in the least.

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