Show HN: What if the speed of light was 5 km/h? • Hacker News Board

Re: Show HN: What if the speed of light was 5 km/h?

#71

Post by iceman_w » Thu, Sep 10, 2026, 5:36 AM UTC

nomilk wrote: post #63

Feels like W goes back (instead of forwards like in an FPS), and S goes forward. Is that intended or just my keyboard being weird? EDIT: ah, by setting 'Speed of light' parameter to 40km/hr I find it a bit more intuitive

What you are observing is relativistic aberration. W does make your velocity increase in the forward direction.

Re: Show HN: What if the speed of light was 5 km/h?

#72

Post by classified » Thu, Sep 10, 2026, 5:42 AM UTC

teekert wrote: post #70

Hmm, by some bug my back arrow first slows me down from approaching c, but then will sudddenly spead me back up (while going backwards), so I get stuck in a dark world. (Firefox on Linux). Edit, maybe it's because the speed shift is so coarse I cross past 0 km/h from back to forwards and reverse too fast... Other than this, very very nice. Love this kind of thing for developing intuiting outside the normal range in w…

> my back arrow first slows me down

That's exactly what would happen ins space.

Re: Show HN: What if the speed of light was 5 km/h?

#73

Post by fennec-posix » Thu, Sep 10, 2026, 5:43 AM UTC

This is what it's like with my new glasses

Re: Show HN: What if the speed of light was 5 km/h?

#74

Post by teekert » Thu, Sep 10, 2026, 5:46 AM UTC

classified wrote: post #72

teekert wrote: post #70

Hmm, by some bug my back arrow first slows me down from approaching c, but then will sudddenly spead me back up (while going backwards), so I get stuck in a dark world. (Firefox on Linux). Edit, maybe it's because the speed shift is so coarse I cross past 0 km/h from back to forwards and reverse too fast... Other than this, very very nice. Love this kind of thing for developing intuiting outside the normal range in w…

> my back arrow first slows me down That's exactly what would happen ins space.

On some more testing, I don't seem to alter direction, just suddenly start to accelerate again. Ah well, it worked mostly.

Re: Show HN: What if the speed of light was 5 km/h?

#75

Post by IvyMike » Thu, Sep 10, 2026, 5:48 AM UTC

The book Redshift Rendezvous from 1990 explores this idea. (TBH the story is a little clunky, but if you like to see someone look at the physics in depth, it's pretty interesting.)

https://www.goodreads.com/en/book/show/1382560.Redshift_Rend...

Re: Show HN: What if the speed of light was 5 km/h?

#76

Post by nielsbot » Thu, Sep 10, 2026, 5:54 AM UTC

IvyMike wrote: post #75

The book Redshift Rendezvous from 1990 explores this idea. (TBH the story is a little clunky, but if you like to see someone look at the physics in depth, it's pretty interesting.) https://www.goodreads.com/en/book/show/1382560.Redshift_Rend...

similarly, Einstein's Dreams is a collection of very short stories that explore different flavors of time. For example: time slows as you near the city center - those who approach it end up frozen forever like the event horizon of a black hole.

https://en.wikipedia.org/wiki/Einstein's_Dreams

Re: Show HN: What if the speed of light was 5 km/h?

#77

Post by shevy-java » Thu, Sep 10, 2026, 6:04 AM UTC

I think this is not possible. There is most likely a reason as to why light has this speed. Naturally it must be tied to energy and interaction of energy with other things. I also don't think "human speeds" applies here because it assumes that humans were decoupled from this, which I don't think we are at all. Besides, humans also use fairly fast things once you go down to the level of molecular biology and chemistry; the chromophore 11-cis-retinal is quite fast in its changes, for instance, and various enzymatic reactions such as by the carbonic anhydrase - up to 10⁶ reactions per second for the latter (assuming there is a sufficient amount of substrate available). That's not slow.

Re: Show HN: What if the speed of light was 5 km/h?

#78

Post by teiferer » Thu, Sep 10, 2026, 6:16 AM UTC

Um, speed of light and gravity are so fundamentally linked that nothing you see would look like that. Just changing speed of light but not adjusting anything else makes little sense.

Re: Show HN: What if the speed of light was 5 km/h?

#79

Post by adamkurkiewicz » Thu, Sep 10, 2026, 6:16 AM UTC

At first sight, this is remarkably more accurate that the "slower speed of light" game from MIT that was made available all those years ago (~2012).

Many issues with the MIT game were discussed here:

https://physics.stackexchange.com/questions/43695/how-realis...

While the thread lists multiple issues, the issue that I found was with modeling temporal aspects of relativistic doppler (I also reported it on the github repo of the "slower speed of light" project, but that doesn't appear to be maintained):

https://github.com/MITGameLab/OpenRelativity/issues/17

In this game, it looks like the temporal component of the Doppler effect is modelled correctly.

Re: Show HN: What if the speed of light was 5 km/h?

#80

Post by baalimago » Thu, Sep 10, 2026, 6:18 AM UTC

So it's without collisions, I take it?

I got confused by the premise. To the fully blind person, the speed of light does not matter. He'll hit the object 5 meters away from him regardless if he sees it or not (as will everyone else, but it'll look weird).