Random Thoughts About God And Physics

[TheresaThoma]

Yup A.P French's Vibrations and waves. I haven't spent too much time with the book yet but it seems to be pretty good.

[Laudate_Dominum]

I've just gotta say, I love space... Other planets and stuff... Woot!

[brianthephysicist]

[quote name='Laudate_Dominum' timestamp='1315867480' post='2303944']
Whoa... That's amesome! I'm jealous. I wouldn't mind hearing more about this research. So are you working Bose-Einstein condensates (or Fermionic!?) and studying phenomena such as coherence? Just a shot in the dark. lol.
[/quote]

Well, my previous theoretical research was studying p-wave scattering to understand Fermionic Condensates. It was tons of fun, but it felt more like math than physics.

My current experimental work is on the Bichromatic Force. We use two frequencies of light, each detuned from atomic resonance by an equal and opposite amount. They are overlapped and after passing through the interaction region are retro-reflected back through it again. Since they are two frequencies, they form a beat pattern. We time our beats as pi-pulses such that an atom sees an incoming pi-pulse and absorbs light, it then sees a second pi-pulse coming from the other direction (from retro-reflected beam) that causes it to undergo stimulated emission.

Light carries both momentum and energy. The energy is conserved by absorption and later by emission. Just as in Doppler forces, there are two times in which momentum is transferred to the atom. In Doppler, the first momentum kick (from absorption) follows the +k vector of the light and the second momentum kick (from spontaneous emission) is in a random direction. Spontaneous emission has no preferential direction, so the average change in momentum will be zero. In Bichro, we follow the same first momentum kick, but instead of spontaneous emission, we use stimulated emission. The emitted light travels in the -k direction, giving a second +k kick to the light. The total momentum kick is larger and it takes less time to occur, giving Bichro a much larger force than Doppler.

I prefer to be able to hand-wave and draw this stuff out and I even have a nice picture that gives a nice sketch of what's happening but I don't know how to upload it. I'll try to figure it out later and I'll post it when I do.


We study various aspects of this force, such as the velocity capture range provided by the detuning and the cooling limit.


[quote name='Laudate_Dominum' timestamp='1315867480' post='2303944']
I'm currently employed as a software engineer but I'm something of a general knowledge enthusiast and had some exposure to physics growing up (my mom and step dad are physicists for example). My understanding is pretty patchy though. lol.
[/quote]

That's pretty cool. What types of software do you work on? Or is it more of a general "whatever my employer asks me to make"?

[brianthephysicist]

[quote name='TheresaThoma' timestamp='1315879457' post='2304031']
Yup A.P French's Vibrations and waves. I haven't spent too much time with the book yet but it seems to be pretty good.
[/quote]


Also, TheresaThoma, I was wondering, will you be studying gravitational waves before the end of the course or is it restricted only to classical waves?

[Laudate_Dominum]

[quote name='brianthephysicist' timestamp='1316020517' post='2304624']

Well, my previous theoretical research was studying p-wave scattering to understand Fermionic Condensates. It was tons of fun, but it felt more like math than physics.

My current experimental work is on the Bichromatic Force. We use two frequencies of light, each detuned from atomic resonance by an equal and opposite amount. They are overlapped and after passing through the interaction region are retro-reflected back through it again. Since they are two frequencies, they form a beat pattern. We time our beats as pi-pulses such that an atom sees an incoming pi-pulse and absorbs light, it then sees a second pi-pulse coming from the other direction (from retro-reflected beam) that causes it to undergo stimulated emission.

Light carries both momentum and energy. The energy is conserved by absorption and later by emission. Just as in Doppler forces, there are two times in which momentum is transferred to the atom. In Doppler, the first momentum kick (from absorption) follows the +k vector of the light and the second momentum kick (from spontaneous emission) is in a random direction. Spontaneous emission has no preferential direction, so the average change in momentum will be zero. In Bichro, we follow the same first momentum kick, but instead of spontaneous emission, we use stimulated emission. The emitted light travels in the -k direction, giving a second +k kick to the light. The total momentum kick is larger and it takes less time to occur, giving Bichro a much larger force than Doppler.

I prefer to be able to hand-wave and draw this stuff out and I even have a nice picture that gives a nice sketch of what's happening but I don't know how to upload it. I'll try to figure it out later and I'll post it when I do.


We study various aspects of this force, such as the velocity capture range provided by the detuning and the cooling limit.[/quote]
Whoa. If I'm understanding you correct I suppose my first question (more later) would be, how does the cooling limit of this technique compare with doppler? Sounds like cutting-edge stuff. That's so amesome. Oh, and what atoms are you working with?


[quote name='brianthephysicist' timestamp='1316020517' post='2304624']That's pretty cool. What types of software do you work on? Or is it more of a general "whatever my employer asks me to make"?
[/quote]
I currently have a contract doing medical software, but yeah, I'll do whatever. I wish I could do hardcore scientific computing but that hasn't quite been my career path. Oh, video games would be sweet too. lol.

[brianthephysicist]

<p>[quote name='Laudate_Dominum' timestamp='1316026096' post='2304655']</p>
<p>Whoa. If I'm understanding you correct I suppose my first question (more later) would be, how does the cooling limit of this technique compare with doppler? Sounds like cutting-edge stuff. That's so amesome. Oh, and what atoms are you working with?</p>
<p>[/quote]</p>
<p> </p>
<p>Well, as of right now, it doesn't really have a well defined limit, it's just what we can experimentally observe. We know it can't reach as low a temperature but it looks like it will be roughly one order of magnitude difference. The big thing with Bichro is that its velocity capture range is about one order of magnitude larger and that it reaches its limit much faster. Around the lab we throw around the analogy of Doppler being like tweezers and Bichro being like a sledgehammer. Also, we use meta-stable Helium 4.</p>
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<p>[quote name='Laudate_Dominum' timestamp='1316026096' post='2304655']</p>
<p>I currently have a contract doing medical software, but yeah, I'll do whatever. I wish I could do hardcore scientific computing but that hasn't quite been my career path. Oh, video games would be sweet too. lol.</p>
<p>[/quote]</p>
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<div>Wow that's really cool. What kind of medical software are you working on? Like imaging software? I think it's amesome, but I'm absolutely terrible at programming lol. </div>
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[Laudate_Dominum]

[quote name='brianthephysicist' timestamp='1316059153' post='2304913']
Well, as of right now, it doesn't really have a well defined limit, it's just what we can experimentally observe. We know it can't reach as low a temperature but it looks like it will be roughly one order of magnitude difference. The big thing with Bichro is that its velocity capture range is about one order of magnitude larger and that it reaches its limit much faster. Around the lab we throw around the analogy of Doppler being like tweezers and Bichro being like a sledgehammer. Also, we use meta-stable Helium 4.[/quote]
I don't know anything about Bichro so forgive me, but is it at a stage where you're experimenting with possible applications, or still more preliminary? I want to say I've heard of He-4 beam experiments for possible nanoscale manufacturing and all that. I figured the pi-pulse, +k vector kicking explanation above had to do with capturing and collimating the atoms anyway, and your sledgehammer analogy is suggestive. What kind of velocities do you get? Do you experiment on different target materials or whatever? Is there any kind of application to microscopy? This is interesting to me as I've never known anyone in your field before. I remember when my mom was in grad school seeing lots of lasers and esoteric gadgetry related to low temperature physics experiments; I tend to imagine your lab in this way. haha.

[quote name='brianthephysicist' timestamp='1316059153' post='2304913']Wow that's really cool. What kind of medical software are you working on? Like imaging software? I think it's amesome, but I'm absolutely terrible at programming lol.[/quote]
Nothing as interesting as imaging software. The stuff I work on relates to the more mundane aspects of running hospitals. Well, to be fair there are interesting things to do from time to time. I'm not super into my work btw, it's just a practical necessity for me. Do you have to do much programming for school and/or your research? Are you into any math software? Do you use Matlab? I recently downloaded an open source program called Maxima and it seems decent. Haven't had time to really get into it yet. lol. I'm interested in Octave too but doubt I'll find time to mess with it any time soon. Anyway, I don't want to start rambling...

Edited September 15, 2011 by Laudate_Dominum

[missionseeker]

[img]http://images.wikia.com/muppet/images/d/d3/VMX-Beaker%26Bunsen.jpg[/img]

[missionseeker]

[quote name='Laudate_Dominum' timestamp='1315867480' post='2303944']



You're amesome.


Spocking out? Woot!


Dang, g2g.. more later
[/quote]

In a 2004 Internet poll sponsored by the BBC and the British Association for the Advancement of Science, Beaker and Dr. Bunsen Honeydew were voted Britain's favorite cinematic scientists. They beat [url="http://muppet.wikia.com/wiki/Star_Trek"][i]Star Trek[/i][/url]'s Mr. Spock, their closest rival, by a margin of 2 to 1 and won 33 percent of the 43,000 votes cast.

[brianthephysicist]

<p>[quote name='Laudate_Dominum' timestamp='1316069611' post='2304941']</p>
<p>I don't know anything about Bichro so forgive me, but is it at a stage where you're experimenting with possible applications, or still more preliminary? I want to say I've heard of He-4 beam experiments for possible nanoscale manufacturing and all that. I figured the pi-pulse, +k vector kicking explanation above had to do with capturing and collimating the atoms anyway, and your sledgehammer analogy is suggestive. What kind of velocities do you get? Do you experiment on different target materials or whatever? Is there any kind of application to microscopy? This is interesting to me as I've never known anyone in your field before. I remember when my mom was in grad school seeing lots of lasers and esoteric gadgetry related to low temperature physics experiments; I tend to imagine your lab in this way. haha.</p>
<p>[/quote]</p>
<p> </p>
<p>It's a little of both actually. Our lab was originally using Bichro for, as you suggested, nano-scale manufacturing. Originally our advisor decided on it for lithography and there have been previous theses written on the success of it for collimating the He-4 beam. I'm not sure exactly what material they used it for, but I know that it was gold with a monolayer of some molecule that is damaged when exposed to the metastable He-4. We are currently going back to the basics and trying to better study the force itself because the theory is not analytically solvable. This means any kind of calculations we do from theory are all numerical, typically Monte-Carlo simulations. The general idea is that the velocity range is dependent on detuning, so the velocity range changes based from day to day, unfortunately, I don't have a rough estimate. I'd have to dig through an old thesis to find it and it would probably take awhile lol. Yea, our lab does look pretty crazy with all of the optics, lasers, electronics racks, and the ever so important vacuum chamber. I do want to stress that I'm the newest member in the group so there's still tons of stuff about the experiment that I don't know yet, but I'm taking it one step at a time and I've learned a lot so far.</p>
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<p>[quote name='Laudate_Dominum' timestamp='1316069611' post='2304941']</p>
<p>Nothing as interesting as imaging software. The stuff I work on relates to the more mundane aspects of running hospitals. Well, to be fair there are interesting things to do from time to time. I'm not super into my work btw, it's just a practical necessity for me. Do you have to do much programming for school and/or your research? Are you into any math software? Do you use Matlab? I recently downloaded an open source program called Maxima and it seems decent. Haven't had time to really get into it yet. lol. I'm interested in Octave too but doubt I'll find time to mess with it any time soon. Anyway, I don't want to start rambling...</p>
<p>[/quote]</p>
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<div>As I mentioned earlier the Monte-Carlo simulations that 'we' run is pretty much what the senior grad student Chris runs. He runs this in fortran. I tend to avoid programming if I can because I'm not very good at it. When I was doing theoretical work, I sometimes had to work with MatLab for numerics and it was tiring. MatLab seemed like a nice program and it worked very well for me. The only other two programs I use are Mathematica and Scientific Workplace (LaTex editor and algebraic manipulator), both primarily for homework. I haven't heard of Maxima or Octave, but I'll have to try them out.</div>
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<div>Don't worry about rambling, that's what half my posts are about lol</div>
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[brianthephysicist]

[quote name='missionseeker' timestamp='1316073139' post='2304945'] In a 2004 Internet poll sponsored by the BBC and the British Association for the Advancement of Science, Beaker and Dr. Bunsen Honeydew were voted Britain's favorite cinematic scientists. They beat [url="http://muppet.wikia.com/wiki/Star_Trek"][i]Star Trek[/i][/url]'s Mr. Spock, their closest rival, by a margin of 2 to 1 and won 33 percent of the 43,000 votes cast.[/quote]

That's amesome! I love Beaker!




Also, why do my posts keep having weird html things?

[MissyP89]

Because you broke it.

[BG45]

Brian, I actually thought of you here on Phatmass when I saw a section at the Newman Used Book Sale I just went to.

[IMG]http://img.photobucket.com/albums/v344/ordos45/real%20life/IMAG0489.jpg[/IMG]

[brianthephysicist]

Aww man, I would've been so excited to see what was there

[BG45]

It was mostly chem and bio, but I saw a few Physics textbooks that would've probably been $100 last semester being sold for a dollar because they were hardcover!