probes

Either the probes can't replicate fast enough or decide to stop replicating/exploring for whatever reasons and there are just not enough/fast enough probes.

This would mean that the only contact would be machine probes who left their civilizations tens of thousands of years into the past.

We found that with RNA/DNA hybridisation that the probes with indels bind with high efficiency [1].

Such probes would be programmed not to initiate contact with worlds with life on them.

So, lots still left to explore and observe with probes in our own solar system.

And even if they send probes, it's not as if they or we send a million of them.

It is actually far more likely than an alien civilization would detect our radio and tv broadcast signals than our space probes.

- Even if it sends out probes, those probes generally fall into the gravity wells of the planets they are sent to over the millions of years.

That probes start having the same problems as the creating intelligent entity has.

A colleague of mine asked me why India was now spending billions as well on space probes when they have so many starving.

> - Even if it sends out probes, those probes generally fall into the gravity wells of the planets they are sent to over the millions of years.

It would be nice if the values for the voyager and Pluto probes counted in realtime their distance instead of displaying a static number.

I guess that's a matter of defining "earth bound." If we don't have people in space but we have probes on all the nearby planets, moons, comets and anything with enough gravity to hold one down, does that count as earth bound?

We've solved the "can we accurately and remotely steer a craft out to the edge of the solar system?" with numerous probes and robots, such as Voyager, the various Mars rovers, and others.

Probes are good for exploration, but colonies are useful too, and it's a shame that we stopped putting in nearly any effort along those lines.