> SCUBA is diving without a tether. It’s popular. Look up saturation diving. The link from the diver to their dive bell — now that's a tether. One critical to

> SCUBA is diving without a tether. It’s popular. Look up saturation diving. The link from the diver to their dive bell — now that's a tether. One critical to human life, unable to be lost for even a moment, and yet which humans freely do freaking oxyacetylene welding around. And yet it still works out fine, in 99.999% of dives. Humans are good at managing tethers! But to be clear, my point isn't that tethered robots would be preferable to or even as good as untethered robots. Just because humans are good at tethers doesn't mean they like them. So of course untethered telepresence robots would be better, if they were practical. My point is that tethered human-equivalent telepresence robots — in combination with human operators who can map their intuitive management of their own body-plan into management of the robot and its tether — will be practical in an absolute sense, long before untethered human-equivalent telepresence robots become practical. We'll have tethered telepresence 'bots doing real, useful stuff out there in the world (decomissioning toxic/irradiated structures in non-polluting ways, say—or replacing those sat divers!), long before we manage to make batteries dense enough to power untethered telepresence 'bots for the same purposes.