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

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

#151

Post by mr_mitm »

santiagobasulto wrote: post #90

Some time ago I had the following shower thought: "the Speed of Light is pretty slow" How i got there: The closest major galaxy to the Milky Way is Andromeda, and is 2.5 million! light-years away. And this is the CLOSEST galaxy, the universe is extremely big. Of course that as you get closer to C, the traveling object will experience time dilation (relative to observer), so the time passed will be less. At 99.999% C,…

It doesn't really make a lot of sense to contextualize a velocity with a distance or a time period.

You think those time periods are large because you see a lot of numbers in the units you chose, or because it is much larger than your lifespan. But in the grand scheme a galaxy is nothing but a spec of dust, 10k years a blink of an eye.

There is no other natural velocity that I'm aware of that we could compare it to, but we can say that the speed of light is the fastest there is, so how can it be slow?

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

#152

Post by futureshock »

atlimar wrote: post #99
santiagobasulto wrote: post #90

Some time ago I had the following shower thought: "the Speed of Light is pretty slow" How i got there: The closest major galaxy to the Milky Way is Andromeda, and is 2.5 million! light-years away. And this is the CLOSEST galaxy, the universe is extremely big. Of course that as you get closer to C, the traveling object will experience time dilation (relative to observer), so the time passed will be less. At 99.999% C,…

> At 99.999% C, the traveler would take ~11,000 years if we add more 9s, is it possible to reduce that number to within a human lifespan?

Of course! You can arrive as quickly as you want as the traveler. You can cross the observable universe in a few hours if you add enough 9’s.

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

#154

Post by mathgeek »

jeanlucas wrote: post #138
rrr_oh_man wrote: post #129

Earlier quoted context omitted.

Thanks! But same here imho: 1,000 seconds = ~0.01 days (~17 min) 1,000,000 seconds = ~11.57 days (~12 days) 1,000,000,000 seconds = ~11,574.07 days (~32 years) 1,000,000,000,000 seconds = ~11,574,074.07 days (~32k years) It all seems quite logical once you put everything into the same unit, I think. Maybe it's just our human calendar/time unit rollercoaster (60*60*24*30*12) that's playing tricks on us here.

Of course it is logical, we are not discussing the math. But it isn't intuitive, you're not used to numbers that big or that grow that fast. Few things go from a million to a billion, especially when related to time.

It’s the units that make it seem unintuitive. 12 days is roughly 0.032 years, and 17 minutes is likewise 0.000032 years. It’s relative to how we were taught to view smaller lengths of time. Of course you could argue measuring time by the rotation of heavenly bodies is more intuitive than counting on your fingers for the hours in a day and days in a lunar cycle.

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

#155

Post by perlgeek »

The wavelength of light is λ = c / f, where c is the speed of light and f is the frequency.

When c is approximately 10^7 times lower, so is the wavelength (if we keep the frequency the same), so now-visible light would have wavelengths far shorter than an atom or a molecule, and probably couldn't be easily detected by biological means.

You could say: sure, maybe we'll just see light at lower frequency. Maybe that's true, but the energy of a single photon is E = hf, where h is the Planck constant. So if we assume much lower-frequency photons, they have much lower energy, and thus become harder to detect.

Lots of other things could be different, like chemistry, heat conduction etc.

At a height of roughly 1.8, at c = 5km/h, light would take 0.1 seconds to travel from head to toe. Nerve signals are much slower than c, so human bodies likely wouldn't exist as we know them.

The list of potential implications to consider is fascinating, endless and maybe even a bit overwhelming :-)

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

#157

Post by [deleted] »

perlgeek wrote: post #155

The wavelength of light is λ = c / f, where c is the speed of light and f is the frequency. When c is approximately 10^7 times lower, so is the wavelength (if we keep the frequency the same), so now-visible light would have wavelengths far shorter than an atom or a molecule, and probably couldn't be easily detected by biological means. You could say: sure, maybe we'll just see light at lower frequency. Maybe that's t…

[deleted]

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

#158

Post by zogomoox »

greysphere wrote: post #86

One oddity of Lorentz invariance is that two non-parallel boosts decompose into a boost and spatial rotation. I've never quite wrapped my head around this and was hoping to get some insight from this simulation. But afaict, I'm not seeing this effect (press W for a bit, the A for a bit and it's not obvious I'm at a different orientation - if I look down at the ground the gridlines are still axial). I don't know if I'…

go past the cubes at near lightspeed, you'll see them rotated; you can see their back planes even before you passed them.

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

#159

Post by saberience »

jeanlucas wrote: post #138
rrr_oh_man wrote: post #129

Earlier quoted context omitted.

Thanks! But same here imho: 1,000 seconds = ~0.01 days (~17 min) 1,000,000 seconds = ~11.57 days (~12 days) 1,000,000,000 seconds = ~11,574.07 days (~32 years) 1,000,000,000,000 seconds = ~11,574,074.07 days (~32k years) It all seems quite logical once you put everything into the same unit, I think. Maybe it's just our human calendar/time unit rollercoaster (60*60*24*30*12) that's playing tricks on us here.

Of course it is logical, we are not discussing the math. But it isn't intuitive, you're not used to numbers that big or that grow that fast. Few things go from a million to a billion, especially when related to time.

Going from a million to a billion isn't some special relationship. It's just * 1000. It's the same as going 11000 or 101000.

I find it frustrating that people seem to think that someone going from 1M to 1B is somehow different to other numerical operations. It's not. It's 1000 times bigger, it's not a huge deal.

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

#160

Post by librasteve »

marcyb5st wrote: post #106
atlimar wrote: post #99

Earlier quoted context omitted.

> At 99.999% C, the traveler would take ~11,000 years if we add more 9s, is it possible to reduce that number to within a human lifespan?

Yeah, it is and the math get's really counterintuitive to grasp since humans (at least me) have trouble thinking in exponential terms. If you accelerate at 1g constantly for 1y you travel 0.5 light years. You do that for 10.5 years and you reach the center of the milky way. You do that for another 4 (~14 total) years and you are in the Andromeda galaxy, and you do that for another 10 years (~24 years total) and you r…

oh, so that’s where all the aliens are … up and cruising around at .99g
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