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  • Jen-Luc Piquant sez: "They like us! They really like us!"

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Nice blog. You are probably the most attractive woman I have ever seen write about physics. But then, this is a lot like thermodynamics, the only class in engineering I didn't "get". Your blog title is also clever. Have a visit to my blog and see if you like it.

Take care,

"...water is pretty conductive in its normal state"

Actually, pure water is not a conductor in its normal state. It's the ions (like Na+ and Cl- from dissolved salt) that carry the current. Sea water is approximately 1,000,000 more conductive than ultra-pure water. (See for example.) Excellent article though!

Ah, count me as one of those obsessive surfers - one can learn so much if they hang around the right places. "Phase transitions" reminds me of an article I just read:

"Researchers have now used x-rays to dissociate water at high pressure to form a solid mixture--an alloy--of molecular oxygen and molecular hydrogen. ...

The researchers subjected a sample of water to extremely high pressures--about 170,000 times the pressure at sea level (17 Gigapascals)--using a diamond anvil, and zapped it with high-energy x-rays."

Gigapascals is a great word, but I'm trying to wrap my mind around the diamond anvil part of this. Can anyone explain?

Atmospheric pressure at sea level is 101 and a bit kilopascals, so 250 gigapascals is not quite 2.5 million atmospheres. (That's one of the easier conversion factors to remember: it sure beats the heck out of converting electron volts to kilocalories per mole. . . .)

I did my thesis work using a diamond anvil cell! Finally something I am qualified to comment on!

The basic premise is quite simple. Mount two diamonds on opposing metal plates. They (the diamonds) are often in a modified brilliant (standard) cut, but have their points polished off to produce a flat tip. Place a small metal gasket between the diamonds and drill a hole in it smaller than the diamond flats. Place sample of interest in the hole, with some pressure medium (I used liquid argon), and screw the two plates together. Because the backs of the diamonds are usually much larger than their tips, you can convert a moderate force into a high pressure (p=F/A). This squeezes the incompressible fluid pressure medium, which transmits the pressure to your sample. I usually worked in the 40-50 kilobar pressure range (40-50,000 atmospheres = 4-5GPa), which is on the low side for most diamond anvil cell work.

By the way, I can assure you that diamonds are NOT, in fact, "forever." If you don't tighten the corners of your cell properly, it is not hard to shatter one or both diamonds!

According to SteveT, "If you don't tighten the corners of your cell properly, it is not hard to shatter one or both diamonds!"

There's a great metaphor for romance in there, but I'm not bitter enough this morning to drag it out.

Years ago (so many it hurts me to recall)I was laid to waste when I first came across the ice phase diagram - at the time sporting just 8 phases. Since then we've had poly water that threatened to jellify the world and turbo/cerebro rocker Joe Satriani treating us to ice 9. Water never ceases to amaze: a nice post Jennifer (et Jen Luc aussi)

SteveT, thank you, that's the kind of nuts and bolts explanation I was looking for. It must be fun "playing" in a lab (or similar), even when your diamonds shatter. I guess nothing lasts forever - in one state or another. (Entropy?) I guess we can safely assume your thesis went well!

Blake, we definitely want only shiny happy metaphors on Fridays and Saturdays - the bitter mishaps can be dragged out on Mondays, when most of us are dragging ourselves into work. :-)

TBB, You're most welcome! Yes working/playing in a lab is fun most of the time. There was a lot of stress (no pun intended!) associated with the diamond anvil cell work, though. I can still vividly remember (after 10 years) the nervous, clenched feeling I got in my stomach whenever I had to tighten the allen bolts on the cell to increase the pressure. I was always holding my breath, waiting to hear the snapping sound that signified that I had just reduced a ~1/2 carat, gem-quality diamond to a pile of white powder! Meeting with my advisor on those weeks was never a pleasant experience. To be fair though, he was a remarkably forgiving man. And yes, the thesis went well enough.

One of my favorite parts of the work was watching exactly the kind of phase transition that Jennifer refers to here. Like water, my argon pressure medium would undergo a phase transition as I changed the cell pressure. At room temp, it was a molecular solid (like ice), and I could see the grain boundaries under a microscope. As the cell pressure increased, the argon would melt and the grain boundaries would disappear. You could go back and forth across the phase line pretty repeatably, watching the argon freeze and melt, all at room temp. I always thought this was WAY cool! I guess that fact that I can derive pleasure out of observing first order phase transitions might suggest that I am just a tad bit geeky.

Great post on phase transitions. Really interesting.

But as a charter member of the gotcha gang, niggling division, I have to note:
"The cool thing -- literally -- is that those experiments weren't performed at skin-blistering temperatures, but hear the critical temperature of liquid hydrogen: 33 degrees Kelvin." Tsk tsk, Jennifer, 33K IS skin-blistering - and how! anything below about -60F causes blisters.


Hi since I agree with the happy weekends, especially now that Halloween & bonfire night are over, .....

Just to add to Steve T and the kind of pressures that make 'real' diamonds (and synthetic diamonds) or even shatter diamonds

Diamonds are formed by prolonged exposure of carbon bearing materials to high pressure and temperature. On Earth, the formation of diamonds is possible because there are regions deep within the Earth that are at a high enough pressure and temperature that the formation of diamonds is thermodynamically favorable.

Under continental crust, diamonds form starting at depths of about 150 kilometers (90 miles), where pressure is roughly 5 gigapascals and the temperature is around 1200 degrees Celsius (2200 degrees Fahrenheit).

Diamond formation under oceanic crust takes place at greater depths because of higher temperatures, which require higher pressure for diamond formation. Long periods of exposure to these high pressures and temperatures allow diamond crystals to grow larger.

250 gigapascals??? whoooa!
Take it easy if checking tire pressures in Britain

And just because it is Sun Day

Lol, I kid you not, I fell asleep on the couch and discovered I am missing a synthetic diamond stud - I think one of you snuck in and stole it! ;-)

Seriously, though, it's interesting to hear real live people talk about their lab experiences and their own trials and tribulations in the physics world, rather than just reading articles. Some of us non-scientists tend to put physicists on a pedestal, so we love it when you communicate on a level we understand. (Steve, now I'm curious about the real-world application of your thesis!)

I see "geekiness" as a term that has now evolved to simply mean that someone likes and knows a subject that someone else doesn't know or care to learn about. Even I have my own little private geeky moments (though my sister will use the more perjorative 'nerd' when she thinks I'm being boring). Physicists who embrace their geekiness have a lot of power at their disposable when they can communicate well.

I give credit to Jennifer for causing me to revisit my Teaching Company catalogue; unfortunately the course I wanted was not on sale (if I'm going to spend nearly $300 I might as well go back to school and get credit for it!). I decided I should go back to basics and "revisit" my college "Physics for Non-Physics Majors" type of course. Elementary to you all, but I also want to see how this professor ( teaches it, besides eating humble pie and starting from the basics. The class I had years ago was theater-style seating, 100 or so students, dry lectures with no fun lab work, and multiple-choice tests. I didn't study for the first test, got a D+, was horrified at that, but ended up with an A- for a final grade, so I know I can somewhat get it. The unfortunate thing about core college courses is that much of the information trickles out of the brain over time while one is pursuing their major, or just living. Professor Pollock appears to have a stellar resume and looks to be a friendly, polytech-looking sort of guy - hopefully he'll be as good they say. (He also sells credit courses through his university.)

Argh, I just looked and the Einstein Relativity course I wanted is now part of a set with what I just bought! There should be some mathematic principle about the chances of when you pay full price for something that it will then go on sale the next day. Time is *not* on my side.

Thanks, Quasar9, for that interesting addition about diamonds and the link, which I'll read when the caffeine gets pumping. I guess we can also thank Blaise Pascal for the barometer, syringe, and hydraulic press.

Off topic: A retrospective of the late Edward Gorey is in town, and I've always been a big fan of his work. I read that besides his avid consumption and contributions to books, he admitted enjoying the X-Files and Buffy the Vampire Slayer - a factoid about him that I did not know. Of course this made me think of Jennifer. :-)

For those not familiar with Gorey:

OK, back to lurking...

I said: Physicists who embrace their geekiness have a lot of power at their disposable when they can communicate well.

...umm, that should be "disposal." Sorry, brain --> fingers --> not awake yet.

Wow, some terrific comments and discussion here, all happening the weekend I was out of town with no time for blog reading! Sorry for being silent for so long...

Thanks to Urijah for reminding me about the salty aspect of water conductivity -- it's an error I make AGAIN and AGAIN, for some reason. One of those physics facts that just won't stay in my brain.

I am so glad Blake and Steve T. hashed out the diamond anvil bit, as I was wondering about that myself, yet had no time to nose around for more information. (I was pretty much relying on the meeting abstract and a lay language paper posted online.)

Robinki, I've got an entire post pending about "The Gotcha Game" -- awfully close to your "Gotcha Gang," but I swear, I came up with it independently (although it's likely I picked it up subconsciously from the Cyber-ether at some point). Should I ever catch up with my workload this week, I'll get around to finishing and posting it. I will also check out Atul's blog once time permits... I promise. And for the record, I never specifically said cold temperatures WEREN'T skin-blistering. :)

TBB, I don't think I'd pay $300 for a Teaching Company course; chances are it'll go on sale eventually. I just noticed a course on statistics that seemed interesting... that's an area where it's extremely easy to get misled, or misunderstand something in an especially crucial way, so it wouldn't hurt to bone up on that area. Although most journalism classes do cover, tangentially, the basics of how to read and use statistics in news stories, a refresher course is often useful from time to time.]

Finally, I am a diehard Gorey fan, as everyone here probably knows. I own the Dracula Toy Theater and everything! So nice to hear he was a fellot X-Files and Buffy fan. The man was eccentric, but he certainly had taste. :)

Hey, I just found your site. I love it!

Water is a truly fascinating substance. It has many phase transitions (I lose track of how many different forms of "ice" there are, and how many phase transitions between the different forms that you can have). All that, and it is one of the more common chemical compounds in the universe. Truly remarkable.

Hi, another diamond anvil cell user here. I tend to work in the 1-10 Gigapascal (or GPa as we like call it) range. A lot of very interesting things happen if you cool things down as well as squeezing them between diamonds. It turns out that a good 50-odd elements become superconducting (another phase transition) if you cool them to close to absolute zero, 23 of those needing at least some pressure. Even oxygen becomes metallic, and superconducting at high enough pressure.

The lab I work in also does really really high pressure stuff, in the 100-200GPa range, and in that case you can sometimes only use the diamonds once! I did hear though that to get the highest pressures, you should select the diamond that didn't break from a pair which didn't survive a high pressure run. A bit like a high-stakes game of conkers. (Do you have that in the US? Its a schoolboy (mostly) game where you drill a hole in a horsechestnut (conker), dangle it from some string, and try and smash your opponent's conker, with the winner staying on to face allcomers.)

The experiments we do are really tricky in fact, since we often want to measure the electrical resistance of something inside a diamond anvil cell, which means spot-welding four tiny gold wires to a sample a few tenths of a mm across (about the size of a large grain of dust). Then we have to make sure the wires don't short-circuit on the metal gasket, or get broken by the sharp edges of the diamond. It's quite difficult!

I have a new appreciation for diamond anvils - they're not merely thingamajigs anymore. You guys rock!

One atmosphere is about 100,00 pascals = 15 pounds/inch^2, for all you Americans with tires. A gigapascal is 10^9 pascals = 10,000 atmospheres, as previously mentioned. But how much is that *really*? Well, 10,000 atm = 150,000 pounds/inch^2, so you'd get a gigapascal of pressure if you took a 150,000 pound weight and balanced it (very carefully of course) on a post with the area of a postage stamp. A diamond anvil cell works in much this fashion except that scientists use a screw instead of a weight to apply force and they use diamonds for the posts. To get 250 GPa, you'd have to stack 250 of the 150,000 pound weights on top of the post. Don't try this at home.

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    Physics Cocktails

    • Heavy G
      The perfect pick-me-up when gravity gets you down.
      2 oz Tequila
      2 oz Triple sec
      2 oz Rose's sweetened lime juice
      7-Up or Sprite
      Mix tequila, triple sec and lime juice in a shaker and pour into a margarita glass. (Salted rim and ice are optional.) Top off with 7-Up/Sprite and let the weight of the world lift off your shoulders.
    • Listening to the Drums of Feynman
      The perfect nightcap after a long day struggling with QED equations.
      1 oz dark rum
      1/2 oz light rum
      1 oz Tia Maria
      2 oz light cream
      Crushed ice
      1/8 tsp ground nutmeg
      In a shaker half-filled with ice, combine the dark and light rum, Tia Maria, and cream. Shake well. Strain into an old fashioned glass almost filled with crushed ice. Dust with the nutmeg, and serve. Bongos optional.
    • Combustible Edison
      Electrify your friends with amazing pyrotechnics!
      2 oz brandy
      1 oz Campari
      1 oz fresh lemon juice
      Combine Campari and lemon juice in shaker filled with cracked ice. Shake and strain into chilled cocktail glass. Heat brandy in chafing dish, then ignite and pour into glass. Cocktail Go BOOM! Plus, Fire = Pretty!
    • Hiroshima Bomber
      Dr. Strangelove's drink of choice.
      3/4 Triple sec
      1/4 oz Bailey's Irish Cream
      2-3 drops Grenadine
      Fill shot glass 3/4 with Triple Sec. Layer Bailey's on top. Drop Grenadine in center of shot; it should billow up like a mushroom cloud. Remember to "duck and cover."
    • Mad Scientist
      Any mad scientist will tell you that flames make drinking more fun. What good is science if no one gets hurt?
      1 oz Midori melon liqueur
      1-1/2 oz sour mix
      1 splash soda water
      151 proof rum
      Mix melon liqueur, sour mix and soda water with ice in shaker. Shake and strain into martini glass. Top with rum and ignite. Try to take over the world.
    • Laser Beam
      Warning: may result in amplified stimulated emission.
      1 oz Southern Comfort
      1/2 oz Amaretto
      1/2 oz sloe gin
      1/2 oz vodka
      1/2 oz Triple sec
      7 oz orange juice
      Combine all liquor in a full glass of ice. Shake well. Garnish with orange and cherry. Serve to attractive target of choice.
    • Quantum Theory
      Guaranteed to collapse your wave function:
      3/4 oz Rum
      1/2 oz Strega
      1/4 oz Grand Marnier
      2 oz Pineapple juice
      Fill with Sweet and sour
      Pour rum, strega and Grand Marnier into a collins glass. Add pineapple and fill with sweet and sour. Sip until all the day's super-positioned states disappear.
    • The Black Hole
      So called because after one of these, you have already passed the event horizon of inebriation.
      1 oz. Kahlua
      1 oz. vodka
      .5 oz. Cointreau or Triple Sec
      .5 oz. dark rum
      .5 oz. Amaretto
      Pour into an old-fashioned glass over (scant) ice. Stir gently. Watch time slow.