Comment by wolfram74 | Hacker News Reader

Comment by wolfram74 | Hacker News Reader

It is early in the morning, so I'm still irritable, but this line is pretty egregious

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The energy savings would need to be drastic, of approximately 30 orders of magnitude to be in range of modern nuclear fission reactors.” He goes on to say: “Fortunately, several energy-saving mechanisms have been proposed in earlier research that can potentially lower the energy required by nearly 60 orders of magnitude.”

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Say the fission reactor they have in mind is a collection of the biggest in human history and is a whole terawatt (1E12 watts). Another 30 orders of magnitude less power brings you down to 1E-18 watts.

For context[1] a typical human cell consumes ~1E-12 watts. You could take a morning coffee poop and put it in a jar with a thermocouple and power your warp drive with the decomposing biomatter if those results are right.

If the energetics are that favorable I would really like an explanation why we haven't encountered space whales, let alone rapidly expanding alien civilizations.

[1]https://en.wikipedia.org/wiki/Orders_of_magnitude_(power)#Be...

For a long time I thought of the sun as being the product of many cycles of recycled material from older suns - but if you look at the cosmic calendar our sun has been around for roughly half (a little less than) the age of the universe! For all we know we could be the first intelligent species to reach the space age in our observable universe.

The older stars were bigger and therefore had much shorter lifetimes, so the Sun indeed is made of the guts of several generations of stars. The Sun is at least the third generation down from the Big Bang.

The noise is huge though, the whole Mesozoic era was just a random delay for our evolution, imagine if it didn't happen or was shorter. Time needed for development of civilization and travel around the galaxy is an infinitesimal perturbation in such huge noise.

It is a strangely worded sentence for sure, but it's probably referring to previous sensitivity analysis done on the original Alcubierre negative mass-energy requirements:

https://en.wikipedia.org/wiki/Alcubierre_drive#Difficulties

60 orders of magnitude is about the difference of the mass of the observable universe to 'a few milligrams'.

If aliens ever visited us they may be blown away that the majority of our bodies are made up of rocket fuel.

University of Göttingen alum here, in our astrophysics courses we used to make jokes about how generous the approximations were. Comparing x^2 with x^5, take log on both sides, 2 ~= 5, so x^2 = x^5 ... Appropriate xkcd: https://xkcd.com/2205/

Something makes me want to continue that xkcd strip with a CS approximation with something about all of those being just constant factors.

One of my favorite derivations in stat mech is for the Chandrasekhar limit where you start by assuming pi=1 because you say stars are cubes.

It currently requires 1e42 (say), and 30 orders of magnitude less brings it into the realm of possibility with a large power plant.

Continuing with the assumptions, it takes /us/ 1E42 watts, but the authors speculate that the universal lower bound is indistinguishable from 0. Much like how we can't make a useful fusion reactor, the universe at large has made loads of them because. If their suspicions are right and the lower bound is so low, it would need to be some incredibly contrived collection of events to not occur naturally with some regularity.

An improbable drive?

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