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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?

#101

Post by ndsipa_pomu »

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?

Yes. If you can manage to get arbitrarily close to the speed of light, the amount of perceived time would get arbitrarily close to zero.

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

#102

Post by ryeights »

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?

Proper time asymptotically approaches zero here right?

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

#103

Post by walrus01 »

tliltocatl wrote: post #84
sampullman wrote: post #69

Earlier quoted context omitted.

You can get a pretty good 1080p60 video at only 6mbps. Depends on how well the sender is encoding I guess, but it shouldn't be too much more than that.

I think the drones don't use a complex encoder because latency.

Some of the more basic ones are a very rudimentary NTSC analog video in to H264 encoder board that is tiny in weight and power consumption. They're using the same NTSC analog video-out forward flight cameras as are used in pure analog FPV. It's also not doing really 'complex' H264 encoding. Very similar to what you would get for the H264 encoder in a cheap $60 IP (RTSP) security camera.

There's more advanced ones that take video input from a MIPI digital video interface or native HDMI input.

Not just because latency but also because of cost, size, weight, power.

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

#104

Post by [deleted] »

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?

[deleted]

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

#105

Post by HPsquared »

rootusrootus wrote: post #35

Whenever I think about light speed being fast, I imagine myself standing at the edge of the solar system and watching a hypothetical photon travel from the Sun to the Earth and taking 8 minutes. Suddenly it doesn't feel like light is really all that fast except at human scales. 5 km/h would be fascinating though.

On the other hand think of the wavelength of light and how absurdly fast the oscillation frequency is to provide a wavelength of a few hundred nm at the speed of light. 8 minutes is a lot of cycles, and 150M km is a lot of wavelengths!

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

#106

Post by marcyb5st »

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?

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 reach what today is considered the edge of the observable universe.

By the time you get there you are basically traveling at a rounding error from C.

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

#107

Post by brontosaurusrex »

rootusrootus wrote: post #35

Whenever I think about light speed being fast, I imagine myself standing at the edge of the solar system and watching a hypothetical photon travel from the Sun to the Earth and taking 8 minutes. Suddenly it doesn't feel like light is really all that fast except at human scales. 5 km/h would be fascinating though.

For the photon the time passed is 0 right?

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

#109

Post by zkmon »

Light doesn't have a "speed" as in the usual meaning of the word "speed". Talking about speed requires defining spatial distances and time durations, which are in turn defined or created by the phenomenon of light.

Light doesn't "travel". It's just an exchange of entangled photons creating the concept of time duration and distance.

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