Thursday, March 30, 2017

Some recent books on conciousness

Recently I finished reading, well, starting three books in a row that were about consciousness.  Which, of course, it quite enough to do a blog post.

The first was Consciousness and the Brain by Stanislas Dehaene.  It was excellent.  Often when we talk about consciousness philosophically we get lost in depths of abstraction.  This was about consciousness as a scientifically observable phenomenon.  How to tell if someone is conscious of something?  Ask them if they saw it.  People are conscious of things when they notice them but not when they're asleep or not paying attention to them or in various other circumstances.  Insects can't report what they see so we'll get back to the problem of insect consciousness later.

It turns out there's a lot of investigation you can do within that framework that's still very interesting.  And all the philosophical debate about whether qualia are separable from observations is neatly sidestepped for now.

Investigations you can do start out with subliminal messages.  If you see a word or phrase for long enough you become aware of it but it has to be present for more than roughly 50 milliseconds for that to happen.  And we can look at a brain with various imaging technologies and see the difference in it's reaction between seeing a number for 40 milliseconds and 80, the difference is apparently very obvious.

The author goes on to talk about how much processing the brain can do on input before it becomes conscious, turning written words into meaning for instance but not parsing entire sentences.  And also that while subconscious cues can influence your immediate behavior their effects fall off rapidly and disappear entirely after less than 2 seconds.  This applies even to the most basic of functions like Pavlovian conditioning.  If two stimuli are present at the same time and subconscious then conditioning can occur but if the stimuli are separated in time then they have to rise to conscious awareness for conditioning to occur.  So consciousness is entirely prior to memory, something I hadn't known at all.

Next up was Stealing Fire: How Silicon Valley, the Navy SEALs, and Maverick Scientists Are Revolutionizing the Way We Live and Work by Steven Kotler.  This is the one I didn't manage to finish.  The idea that altered states of consciousness can be useful is one that I was interested in but the book ended up being blindly and shallowly enthusiastic about the concept in a way that I thought wasn't really teaching me anything I could rely on.  The author continued to just give examples in which altered consciousness could be cool without ever touching the limitations or potential drawbacks.  In Consciousness and the Brain for instance Dehaene talked about the power of sleeping on a problem and how your subconscious might come up with an answer for you, but also the need to think it over carefully consciously first and the need to double check the answer consciously later since intuition isn't always reliable.  Stealing Fire just talked about how subconscious processing was really cool and powerful without talking about what had to happen before and after.  It also didn't really have any clear idea of what it meant by the word consciousness and conflated altered consciousness and unconsciousness in its examples.

Finally, there was Other Minds: The Octopus, the Sea, and the Deep Origins of Consciousness by Peter Godfrey-Smith.  I enjoyed that book but I wasn't blown away like I was by Consciousness and the Brain.  Octopuses and other cephelopods are cool animals which diverged evolutionarily from humans back when nervous systems were measured in the hundreds of neurons.  Yet, somehow these creatures evolved a very sophisticated intelligence entirely independently.  Much of the book was taken up by describing Octopuses, Squids, and Cuttlefishes - their physiology and psychology - and I found that bit very interesting.  The author also had some ideas about consciousness which he shared which I thought weren't very interesting, but that was a small part of the book.  The main argument was that cephelopods can't have a reflective consciousness like we do because a human can hear themselves talk but a squid can't see itself change color to communicate.  Aside from the obvious objection that congenitally deaf people seem to have reflective consciousness the author relies a lot on introspection to formulate his idea which is notoriously unreliable.  I'm sure the author is correct when he says he always thinks in words but people are different in how they think.  I know that I often go to explain an idea and get to what seems like a simple part of it that seems like it should be a single words but then as I unpack it mentally it turns into a sentence then a paragraph.  Still the way an octopus can change color to match its surrounding without being able to see color itself was very interesting and overall I'm glad I read the book.

Wednesday, March 8, 2017

Blue Origin's New Glen rocket

This is an exciting time to be someone interested in spaceflight.  Not as exciting as the original space race, of course, but hopefully we'll get close within the coming decade.  SpaceX has been making a lot of news with its landings of the first stages of its rockets after using them and its big plans for future Mars missionsh and sending people around the moon.

The United Launch Alliance, which handles most of the government's launches and has a very good reliability record, also has some fairly ambitions plans it's announced involving the development of the space near Earth and it's next generation upper stage.  But probably the most exciting competitor to SpaceX right now (besides NASA) is Blue Origin.

SpaceX has its Falcon 9 which is launching satellites now and its more ambitious and out there ITS.  Blue Origin has until now had its New Shepard rocket for shuttling tourists up to space briefly but recently its been talking more about the New Glenn, a vehicle somewhere in ambition between SpaceX's existing and imagined rockets.  You can watch the video Blue put together about the New Glenn here.

This is a rather large rocket.  Not quite Saturn V large, as you can see here, but close.
There are apparently two different configurations it can fly in, one with a third stage and one without.  The two stage version is the one they made the video of and which they provided some more details for recently.  It's not much taller than a Falcon 9 but is much thicker, at 7 meters in diameter to the Falcon 9's 3.7 meters.   The Falcon had to be long and thin in order for SpaceX to ship it by truck all the way from California, where they are made, to Florida where they are launched.  Blue Origin has invested in a big factory in Florida near their launch pad so that isn't as much of a concern for them.

There are still a number of unkowns for the 2 stage New Glenn but we know how large a payload it can send into low Earth orbit, 45 tons, and how much it send on its way toward geostationary orbit, 13 tons.  This compares with 22.8 and 8.3 tons for the Falcon 9.  It's interesting that the numbers are so far apart for the New Glenn compared to the Falcon 9 but there's a reason for that.

Remember from back when I blogged about rocket performance that the amount you can accelerate for a rocket is related to how much of the combined rocket/payload mass is fuel.  The New Glenn seems to have a fairly heavy rocket engine for its second stage.  That means that it can lift a heavy payload into orbit quickly before gravity has had time to cause too much in the way of a slowdown.  But it also means that the total non-payload mass of the second stage is higher so even if the payload goes down to something fairly small the engine and other weights will still prevent the overall mass ratio from getting too high.  Hence the stage will have a hard time getting a reasonable payload into higher energy orbits.

I suppose that has to do with the optional 3rd stage.  If you're going to have a third stage you want your second stage to burn it's fuel fairly quickly with a high power engine so that the third stage can get to its business.  I'd imagine that the adding the third stage would add a bit to the low Earth orbit payload of one of these rockets but would add far more to how much it can get into a GTO orbit.

The other big difference I noticed, besides sizes, between New Glenn and Falcon 9 was how the rockets are supposed to land.  SpaceX likes to land the Falcon 9 back on land when possible but also has a barge that floats out in the sea for the rocket to land on if the Falcon 9 doesn't have enough extra fuel after getting its payload to space to send itself all the way back to the pad it took off from.  SpaceX is clearly thinking about pad landings as what they want to do in the future in order to quickly refurbish the rocket and launch again.

For New Glenn landing at sea seems to be the idea with a return to the launch site being something that they're not really considering seriously.  You can see this in the ship that they're using.   Rather than cheap barge they seem, in the video, to be thinking about using a second-hand tanker with a big landing pad re-fitted onto the top.  The side-thrusters on a tanker aren't very powerful and so it would have to be moving forward to keep good control of its orientation to provide a stable landing site but overall it can give a much bigger target for the rocket to land on and in heavier seas too.  Also, it should be able to sail back to port much more quickly than SpaceX's barge can.  On the other hand it will probably be a lot more expensive to operate too.

So Blue Origin is investing in a bigger, more powerful ship to make landing at sea easier and SpaceX is mostly thinking about returning to land with sea landings something of an afterthought.  I suppose time will tell which is a better strategy.

Rockets VII: Staging

See also parts  I ,   II ,  III ,  IV ,  V , and  VI . Space is sort of hard to get to.  You've got one of the Space Shuttle Main Engi...