3 ms·

What’s the bandwidth problem? Could we modulate the light coming from our star just so?

• denton-scratch 5y ago
  https://space.stackexchange.com/questions/6207/what-bitrates-are-currently-achievable-for-communication-with-interplanetary-spa https://space.stackexchange.com/questions/6207/what-bitrates... The greater the distance, the more the signal is attenuated, so the harder it becomes to distinguish signal from background-noise, so the slower you have to send. 'Modulate the light from our star': Not sure how one might set about that. As things stand, we need extremely sensitive instruments to detect the starlight-modulation caused by orbiting exoplanets. A planetary-scale modulator would give you a bandwidth in the order of one bit per orbit. Supposing we could construct a device that could modulate sunlight, it would need to be big - orders of magnitude bigger than anything humans have ever made. Our interstallar probe would have to deploy such a device on arrival, in order to 'call home'. I suppose it's conceivable, as an idea; but the cost of such a project would be unimaginable, and the benefit would be useless information: e.g. "There is life on this planet; but you have no chance of getting here, and they have no chance of getting to you". That's not actionable information. And you'll be getting the signal 20,000 years after launching the probe; that's the span of all of human civilisation. There's every chance that humans 20,000 years in the future would not be very interested in a signal from a probe launched by their 'primitive' ancestors. That's if they had any cultural memory from their ancestors that there ever was such a probe; but how much do we know about the culture of humans 20,000 years ago? If they had launched a probe, we would have to learn that from fossilised bones, which seems far-fetched.
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