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moralprolapse t1_j4yu3i0 wrote

Reply to comment by Weed_O_Whirler in Whats stopping us from sending a probe into a black hole if we haven't already? by stealth941

So does that mean all the SETI stuff is basically pointless? Is there even vaguely conceptualized broadcasting technology that could be built consistent with the laws of physics that could hypothetically reach us from another solar system?

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mfb- t1_j4yvrjf wrote

We could communicate with an alien civilization with Earth-equivalent technology over something like 100 light years. It's more difficult than communication with Mars - you need more power, larger antennas and you'll get a lower bandwidth - but it's possible. If the aliens have more advanced technology then the distance could be much larger.

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moralprolapse t1_j4ywwen wrote

Is that 18 quadrillion number wrong then? Or what am I missing about that? Because that order or magnitude doesn’t even sound like a real number. If I’m counting zeros right, that’s 18 thousand million million times more power than doing it from Mars?

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mfb- t1_j4yyr6f wrote

It's assuming identical conditions otherwise.

  • Replace the ~1 meter antenna of a Mars spacecraft with a 500 meter telescope for a gain of 250,000.
  • Increase the power from ~100 W to ~5 MW for a factor 50,000.
  • Replace the 70 meter antenna of the Deep Space Network with another 500 meter antenna for another gain of 50.
  • Replace the 1600 light years used for the 18 quadrillion number by 100 light years for another gain of 250.

Combined that's a factor 150 trillion, so we are only worse by a factor 100 or so. We won't get the multi-megabit connections we can get from Mars, but it's still good enough to transfer tons of information over time. There is no rush - it will take 100 years to arrive anyway.

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Weed_O_Whirler t1_j50tbgd wrote

The 18 quadrillion is to get out to 1600 light years, as opposed to 100 light years as /u/mfb- is talking about.

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