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Comment by threepipeproblm | Hacker News Reader

You're saying that achieving 2.7% of the theoretical efficiency is good?

Many car engines have an efficiency of around 20% for example, as compared to the maximum theoretical efficiency of 67%. If car engines performed only well enough to meet your standard of amazingness, your gas costs would be 7 or 8 times higher. Or if you used a modern Toyota engine for comparison, something like 14 times higher.

Obviously I took an example from a different sphere for comparison... if you really find this to be an astonishing result can you elaborate?

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Not to belittle the internal combustion engine but that's just the theoretical efficiency of chemical combustion. It's a local maximum. That's tiny compared to the global maximum energy available from the same amount of fuel.

As a trite comparison, it's a similar to arguing the theoretical maximum speed that a person can run. Interesting, but doesn't tell you anything about the maximum speed that a person can move.

The speed of light in a vacuum, though, is qualitatively different. It's not a local maximum, it's the global maximum.

Anyway, I reserve the right to be impressed. I spend enough of my life being jaded and cynical. Sometimes I see things like this and it makes me think about stuff that I take for granted.

Your car is not operating at 20% efficiency of theoretical limits if you take the whole energy pipeline into account. You know... fusion, sunlight, plankton, oil, refining, combustion, mechanical energy. On the other hand speed-of-light to actual ping times is an end-to-end efficiency calculation. Plankton in particular is terrible at converting energy.

sun -> mj-PV -> battery -> electric motors run circles around those.

> Plankton in particular is terrible at converting energy.

Says the person who can't even photosynthesize!

On the other hand how well are we doing when it comes to achieving the maximum theoretical speed for interstellar spacecraft? :-)

You car is million times slower than the speed of light :)

10 million. Light: 300000 km/sec, car: 0.03 km/sec

My car is a lot faster than 108 km/h (0.03 km/sec) :)

In the context of the speed of light, it really isn't.

greydius corrected me asserting that the factor between ligth speed and car speed is 10 millions, and not one million as I said.

But in true there are production cars that pass 430 km/h, resulting in a factor of about 2.5 millions. A lot less than 10 millions.

https://en.wikipedia.org/wiki/Production_car_speed_record

You should not compare the fastest car speed, but the average car speed, which for this argument would probably be closer to 200km/h. That puts it in a factor of 5 million, which is within one order of magnitude of the original guess.

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