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Comment by AngryParsley | Hacker News Reader

The guy is right. If you can send stuff to Mars, sending stuff to Saturn isn't much harder. In fact, we already do send probes around the solar system.

The problem is moving people in space. Space is the ultimate desert. People need all kinds of supplies to stay alive and healthy (air, water, food, gravity, etc). They also need to be shielded from cosmic rays and solar events.

I've said it before and I'll say it again: I doubt large numbers of biological humans will ever participate in interplanetary travel. I bet brain-in-vat or uploading technology will show up before payload costs get low enough for average people to buy tickets to Mars. A brain in a vat doesn't need gravity or exercise or space to roam around in. It needs less food and water than a full human body, and it can be shielded easily.

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If my brain were in a vat, my need to travel would be significantly reduced. The only reason I can think of would be if I wanted to interact with a distant environment with less latency.

Good point, but I think it's more general than that: A brain in a vat's need be in a particular location is significantly reduced. Interaction with remote things is limited only by light speed, and possibly bandwidth.

Travel costs for brains in vats are significantly reduced. Not only is travel cheaper monetarily, but the experience of travel can be completely hidden. Instead of sitting in a seat and looking out a window, you could spend your time in a VR world or interact via robots. The only reason you would want to stay in one place is to interact with the nearby environment at low latency.

In the end, uploads are the way to go. You can run them faster and travel cost is just data transfer cost.

Aside from propulsion, which is solved at least for space probes, the great problem of outer-planet exploration is bandwidth. Using a microwave high-gain antenna, the data rate at Saturn is on the order of 10kbits/s and New Horizons would have to cope with 1kbit/s at Pluto. This is incredibly small for instruments capable of taking high resolution pictures.

So the next revolution in space exploration would have to tackle the data problem; optical or near-optical lasers for transmitters and standard photosensors (CCD) for receivers. It is technically possible to use off-the-shelf components, the remaining difficulty being the beam aiming system.

These dudes making a Bose-Einstein Condensate out of photons might be able to give us coherent light at UV or even X-ray frequencies, which would be rather nice for communication: http://www.nature.com/nature/journal/v468/n7323/full/nature0...

By the time technology gets to the point where a brain can be put into a vat I suspect all the neural connections could just be fully virtualized. Neural processing would become a whole lot faster at that point. Space travel could hypothetically take place inside a laser.

Even at that, the Milky Way alone is 100k light years in diameter.

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