This implies the possibility of much better compression than we currently have available.
I forget what that particular bit of math is called. Theoretically, there's an equation which creates that number which might be much shorter than the data itself.
Every piece of data in a computer is essentially a long hexadecimal number. However, the timing still beats shipping computonium from star to star.Īfter that comes bulk data at. It does, however, require some processing power.ĭata sent with high-powered, new compression alogrithm by message laser: Very expensive, but it takes a long time - months/years to decompress. Uncompressed data sent by message laser: INSANELY EXPENSIVE, but very easy to decode on the other side.ĭata sent with ordinary compression by message laser: Incredibly expensive, but once again, fairly easy to access on the other side. So imagine a price structure that looks like this: The corollary is that bulk/unimportant messages go by memory diamond, and high-priority messages go by laser (they only take ten years to get there.) The economics of pricing, particularly with multiple destinations at multiple distances, which also imply multiple bandwidths, get interesting, however. I've got the flu, so I'm not even going to think about checking your math, but I think you've got the right idea barring a really incredible improvement in compression protocols.* Of course, this is just an idle back-of-the-envelope amusement and I've probably borked my calculations somewhere. Which in turn might imply an answer to the SETI silence aspect of the Fermi paradox. And even if we allow for a 10,000:1 mass ratio for our data-carrying starwisp, and impose the same 10% efficiency on its launch laser's energy conversion as on our communication laser, we get 1,000 bits/joule out of it.Īs long as we ignore latency/speed issues, it looks to me as if Tanenbaum's Law implies a huge win for physical interstellar comms over signalling. Even if we allow individual photons to count as bits at 10 light years' range, our laser still maxes out at around 4 joules/bit. Double the energy for deceleration and we still have 2 x 10 6 joules, to move 10 14 bits. So, roughly 4000 joules/bit.Ī packet of memory diamond with a capacity of 1 x 10 14 bits has a mass of roughly 10 -8 grams. It will deliver 0.82 x 10 14 bits of data. Running a laser for 10 years will emit 3.56 x 10 17 joules in that time, at 10% efficiency, so roughly 3.56 x 10 18 joules of energy is consumed. Here's my initial stab at it, which is probably wrong ( because it's a Saturday night, I've been working for the past nine hours or so, and I'm fried): Ignoring latency (it will be one year per light year for lasers, higher for physical payloads), which is the most energetically efficient way to transfer data, and for a given energy input, how much data can we transfer per channel? I'm going to arbitrarily declare that for starting purposes our hyper-sensitive detectors need 1000 photons to be sure of a bit (including error correction), so we can shift 2.6mb/sec using a 1Gw laser.Ħ. If we increase the bit rate we decrease the number of photons per bit, so this channel probably limits out at significantly less than 1Gbit/sec (probably by several orders of magnitude). Our reference interstellar comms laser, for an energy input of 1GW, will be able to deliver 2.6 billion photons/second to a suitable receiver 10 light years away, while switching at 1Hz. And we're going to assume there's another laser at the other end to allow our alien friends to decelerate it (so if you need xGj/gram to reach a specific speed, we can allow for 2x Gj/gram for the trip).ĥ. We're going to ignore the sail mass, to keep things simple. We will assume that we can use a laser-pumped light sail (with laser efficiency of 10%) to transfer momentum directly to a hunk of memory diamond. Our "tape" package will be made of something approximating the properties of memory diamond, i.e. We can communicate with them (and want to communicate with them) by two means: we can beam data at them via laser, or we can send a physical data package (a "tape" travelling cross-country).ģ. Postulate that we make contact in the near future with an extra-terrestrial intelligence ten light-years away.Ģ. Which leads me to ask the following question:ġ. It's a profound insight into the state of networking technology: our ability to move bits from a to b is very tightly constrained in comparison with our ability to move atoms, because we have lots of atoms and they take relatively little energy to set in motion. TNTT MORSE DECODER AND SEMAPHORE FULL
Tanenbaum) is flippantly expressed as, "Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway". Tanenbaum's Law (attributed to Professor Andrew S.
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