5 ms·
There’s a lot of discussion here on how (or even whether) a ‘reflectometer’ (I had to look up what that even meant) works. However, I’m more interested in the
by qubex 6y ago
There’s a lot of discussion here on how (or even whether) a ‘reflectometer’ (I had to look up what that even meant) works.
However, I’m more interested in the things I do understand, and in this case, my question is: considering the fact that there needs to be another (remote) computer to receive the readings, and considering that we’re speaking of processes that ‘degrade’ the cable dangling into the nuclear borehole at an alarming rate, just how does one go about performing an ordinary electrical transmission of data over those distant ranges in those minute times? The latencies are enormous and therefore clearly we’re not talking something like TCP and it’s three-way-handshake SYM/ACK kind of response.
And once the blast approaches the surface (assuming it doesn’t breach it)… is it sufficient for the computer to (comparatively) leisurely transmit its findings whilst it’s in the process of falling into the enormous crater that’s opening up beneath it? Can one presume that the power remains stable long enough for this to occur? (Assuming that the power supply has been destroyed and/or the cables jolted loose, how long does the machine “stay up whilst falling down”?)
- cosmiccatnap 6y agoThis is alot of assumptions in an age of paper pencil and telephone.
- jacobush 6y agoThe story doesn't say, but one could imagine electrically copying the communication in real-time on another wire back to the bunker or something. Or if the test is deep underground, just walk up to the PDP-11 and load it onto a truck.
- qubex 6y ago> the story doesn’t say [...] electrically copying [the signal] back to the bunker or something That’s precisely my point: how do you reliably “copy a signal back” if one terminus of the cable cannot be relied upon to exist for long?
- raldi 6y agoUnderground nuclear tests don’t make huge holes in the surface. That’s the whole point. Here’s what they look like at ground level: https://www.atlasobscura.com/articles/heres-what-an-underground-nuclear-test-actually-looks-like https://www.atlasobscura.com/articles/heres-what-an-undergro... Plenty of room for the computer to survive.
- danbruc 6y ago...if the test happens deep enough to contain the explosion. But even an initially contained explosion may produce a crater later when the pressure in the created cavity drops and the cavity collapses.
- qubex 6y agoEnormous subsistance craters are what I had in mind when I wrote “enormous crater”.
- raldi 6y agoThey’re not enormous relative to the length of LAN cables.
- chrisseaton 6y agoI don't know how you'd describe the image you linked to except a 'huge hole in the surface.'
- raldi 6y agoTo me, it’s just a depression (something shallow a computer cannot fall into), whereas the comment above made it sound like a pit (something deep it can fall into).
- deleted 6y ago[deleted]
- jiveturkey 6y ago> there needs to be another (remote) computer to receive the readings, TDR does not use a remote computer/signal processor. The reflection (the 'R' in 'TDR') comes back to the source.
- qubex 6y agoThe computer is in the process of being blown up because it’s sitting on top of an underground nuclear explosion. It has to relay its data somewhere.
- lostlogin 6y agoThe crater may not be as colossal as I imagined, but the ground lifted a lot going out a long way. I’d imagine that anything with spinning disks would be quite sad even when quite far away.