Yup, science is much more fun, but engineering gets the job done. 
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Go play laser quest…
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You’re not the first person to ask me that. Somewhere around the turn of the millennium, when one of the prequels was coming out, a journalist from Empire mag was put through to me at work with a question about the feasibility of light sabres. We chatted in a bit of detail and I pointed out a few difficulties* which meant that for now at least the idea was not really a viable business proposition. Then I forgot about it.
Next thing I know my brother-in-law, a huge film fan and sometime buyer of Empire, is on the phone saying I’ve been extensively quoted in the mag by Yoda no less (the journalist had written up his side of the Q&A in Yoda-speak). My B-i-L still thinks it’s the most significant technical publication I’ve ever had !
When we finished up on the SDI project I came back to the UK and my closest colleague went to Livermore and built the laser which did this
https://str.llnl.gov/str/April06/gifs/Soules2.jpg
That’s one inch thick steel. The hole took a few seconds to melt. The eventual plan was to fit the laser and its power source onto a Humvee. The power source was a one magawatt battery (almost more impressive than the laser) !!
VB
*Stopping the beam, sourcing enough power, avoiding being splattered by molten debris, etc, etc …
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The only good bit in Star Wars I is the bit where Liam Neeson melts that blast door.
Hopefully one of them wasn’t very tall, dressed in black and having to wear a special mask for his laboured breathing…
Always facinating to hear about some of the extraordinary science shit you got up to.
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Four riddles around revolution.
About a week to answer, I guess.
Vinyl baffled me, so gave up.
The third one isn’t really about revolution. The answer is just the same if you run the two sections in a straight line.
VB
Hard to know where to pitch in this thread.
Learn quickly from the pro, or ask those still interested in growing self up? Both I hope.
Me second class, but educated to hear learned voices.
Duller cousins may endure only three hours lie down.
Still listening.
Diagrams [visual representation of data] much quicker way to glimpse understanding.
The simple lessons are right, but incomplete.
Data giveth not equations.
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Strictly speaking it’s negative ‘effective’ mass https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.118.155301, where the mass is defined through the dispersion relation https://en.wikipedia.org/wiki/Effective_mass_(solid-state_physics). If I’ve understood things correctly the material involved in this experiment wouldn’t have negative gravitational mass only negative inertial mass. So the force acting on it due to gravity would be in the same direction as the force acting on all other matter. But its motion in response to that force would be in the opposite direction.
VB
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It’s all a bit Skylark 
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Never has “How d’ya mean?” resonated so much.
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Believe me, I sympathise. I did the Solid State physics option for finals (mostly because our tutor was absolutely brilliant and this choice was a banker at exam time). But I think if you really want to be comfortable with dispersion relations in that area then you need to work with them more or less every day. People who do that are said, by the rest of us mortals, to inhabit k-space. k-space makes Wonderland look normal. A touchstone for them is that they can explain what the significance of a Brillouin Zone https://en.wikipedia.org/wiki/Brillouin_zone is without having to open a book to remind themselves. I understood it well enough (not ‘well’, just ‘well enough’) for a few weeks in May and June 1980 to get through the exam paper. Then it went. For good I’m afraid.
VB
wtf is that all about? I have just spilled my brain on the floor…
Complex, insoluble & ultimately frustrating.
A Brillouin zone, yesterday.
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It has always been the stuff of myth and legend, but I now know beyond doubt that the hanging gardens of Babylon DO really exist. My life is complete.
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Stu’s getting ready to ship all of this up to Chelsea for the flower show. Monty Don has already highlighted this topical WW3 garden as one of the favourites in the ‘modern’ category.
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Honestly, I can’t remember. If you’re interested in the details of the way that solids behave then I recall that this kind of analysis can give you a lot of insight. It can help you design ‘better’ materials for certain applications, or interpret the patterns you get when you scatter X-rays or neutrons off crystals for example. If you don’t do this sort of thing for a living though then you and Monsieur Brillouin will never need to get acquainted. You can be grateful for that, trust me.
One of the scary things about working in a physics department was the extent to which things that some of my colleagues regarded as everyday, and their ‘bread and butter’ if you like, were just never going to be within my reach, at least not in enough detail for me ever to be able to use them. This, for example Clebsch–Gordan coefficients - Wikipedia. Or this Nonlinear optics - Wikipedia at least in its theoretical form. I have seen the second of these do some genuinely spectacular real-world things in the lab. The military got very excited about it for a while (maybe they still are, but just don’t talk about it any more).
VB