Fermi National Laboratory


Questions and Answers from Virtual Ask-a-Scientist of October 9, 2002

More information about the program

Moderator
Welcome to Fermilab's Virtual Ask a Scientist. Don and Jocelyn are ready for your questions!

Moderator
On this webpage you can see Live Events from the detectors of CDF and DZero http://www.fnal.gov/pub/now/live_events/index.html

Moderator
On the Fermilab website you can find a High Energy Physics timeline, explaining who discovered what and when. This is the url: http://www.fnal.gov/pub/inquiring/timeline/index.html

Trish
What type of schooling is required to become a Fermilab physicist?

Don Lincoln
Hi Trish, we'll both be answering this question.

Moderator
Physics questions from real people and physics answers from Fermilab scientists. http://www.fnal.gov/pub/inquiring/questions/index.html

Don Lincoln
Jocelyn is younger and can tell you about her experience. But since she's not a Fermi physicist, I can tell you what I needed. I got a Bachelor's degree in physics and a separate one in math. I then got a Masters and a Ph.D. in physics. After that you continue with an advanced apprenticeship, called a postdoctoral appointment. After that, you're in!

Jocelyn Monroe
I am a graduate student doing research at Fermilab for my Ph.D. thesis. To get here, I majored in astrophysics in college, then worked for a year at Fermilab in the Beams Division (yes, they hire undergraduates). I have been in grad school for 3 years so far. I'll probably get my Ph.D. in another two years. So, it takes a while, but it's worth it!

Moderator
The Fermilab Education Office offers seven programs for under-graduate students: http://www-ed.fnal.gov/lasso/program_search/undergrad.lasso

Moderator
Jocelyn works for the MiniBooNE experiment. To learn more about MiniBooNE, take a look at there webpage: http://www-boone.fnal.gov/

Moderator
Also take a look at DZero's webpage, which is Don's experiment. http://www-d0.fnal.gov/

Moderator
Fermilab produced its first high-energy particle beam on March 1, 1972. Since then hundreds of experiments have used Fermilab's accelerators to study matter at ever smaller scales. Here an overview of the top ten achievements so far. http://www.fnal.gov/pub/inquiring/physics/discoveries/index.html

Kevin
Don... How are things going for DZero with RunII?

Don Lincoln
We're off and running. It's a very exciting time for DZero. We started our run in March of 1991, and we have spent the intervening time getting to understand our detector. Currently we're taking great data. In fact, we're breaking records on our data taking rate every day. We are sifting through the data and will be releasing results soon. We've even sent people to conferences to tell other experts the preliminary results. Stay tuned, because the rate will pick up even more in the next few months.

Moderator
The Tevatron set an all-time luminosity record of 36E30 today! http://www.fnal.gov/pub/now/lumrecord-10-9.html

KMichael
Jocelyn, so, what's going on at MiniBooNE right now?

Jocelyn Monroe
Well, MiniBooNE started taking beam data this past August, so it's a very exciting time because we're all working hard to make sure the data makes sense and that we understand the response of the detector. So far we have about 1000 neutrino candidate events. This is 1/500th of the data we hope to take in the next two years. Although this doesn't sound like a big deal, the experiment took about 5 years from the time of the proposal to the first beam, so there are a lot of very happy collaborators on MiniBooNE right now.

Moderator
Check out some other high-energy physics resources: http://www.fnal.gov/pub/inquiring/more/more.html

Kevin
Again to Don...Are you where you thought you'd be at this point?

Don Lincoln
Realistically, yes. The detector is 5000 tons and contains about 1,000,000 electronic channels. It took 4-5 hundred physicists about 5 years to put together. So, as you could imagine, it takes a while to understand how everything works. We don't buy a detector off the shelf (although we can buy many components). So since everything is first article, we'll spend a while understanding the detector. But now we have a good idea of how it works and it's time to start using the detector to make the measurements that we want to make.

Matt
I don't understand why pi can go on and on... What is the reason? I have heard that it is because it kind of floats around between the first and 360th degree, but I still don't get it... Can you help?

Jocelyn Monroe
The number pi relates the circumference C of a circle to its radius, C = 2*pi*radius, however, it's not a special number - there are lots of other numbers that go on forever, like 1/9. The fact that it goes on forever happens just because the number can't be written as the ratio of two integers. Does this help?

Jocelyn Monroe
Oops! What I meant to say is the number pi goes on forever *without repeating* since it can't be written as the ratio of two integers. The number 1/9 can be written as the ratio of two integers, which is why it goes on forever but repeats...

JonathanRoss
Hello and thank you for taking my question. Please forgive the basic nature of my questions before I even ask them (your jobs are to discover not disseminate). However, given that you're already committed to wasting some of your time, I'd be a fool not to take full advantage of it. I actually have two questions, both of which I prepared before hand to minimize my invasiveness on science. Is my understanding of quantum mechanics correct in that it states nothing more than energy (and matter) is packaged in some sort of packet? IOW, 19 out of 20 times this will occur instead of 95% of it will go this way and 5% of it will go that way? If that's correct I understand how that would make all the difference in the world but why is this at such odds with Relativity? Those questions can be considered subatomic questions that together compose only one atom of question, I'll ask the second one a bit later...

Don Lincoln
Thanks for the question. I'll answer it now.

docv
I'd like to know as a high school science teacher what easily available equipment or demos are available to stimulate student interest in high energy physics. I've been at workshop at which a cosmic ray detector was built, but otherwise can't think of any projects to excite students. Typically we spend the year building the foundations of high school physics, but rarely have more than a day to discuss "esoteric" subjects such as light leaking at the edges of black holes, dark matter, quarks, etc..

Jocelyn Monroe
Hi docv, thanks for the question. I'm looking up some references now.

Moderator
Learn more about high-energy physics acronyms: http://www.fnal.gov/pub/inquiring/more/acronyms.html

Moderator
Here are some resources about high-energy physics for teachers: http://www.fnal.gov/pub/education/k-12_programs.html

Don Lincoln
Quantum mechanics actually states a couple of things. The "oddest" behavior is that it gives the non-intuitive result that you can't predict how a small particle will work with perfect precision. The trick is that quantum mechanics can predict the probability that a particle will do a particular thing (say go left or right), but it can't predict which direction a >>particular<< particle will go. But if you have a bunch of particles, you can predict on average how many will do each.

Matt
Thank you, Jocelyn. Is pi the only number that goes on forever without repeating?

Jocelyn Monroe
Nope! There are as many irrational numbers (numbers that go on forever and don't repeat) as rational ones (go on forever and do repeat). Another good example of an irrational number we use all the time is "e" which is related to the natural log.

Don Lincoln
Quantum mechanics isn't at odds with relativity. In fact, Paul Dirac wedded the two theories in about 1929(?). One of the coolest things about the equation that he derived is that it actually predicted antimatter, two years before it was discovered.

Matt
Pi is 3.14...; what number is "e"?

Jocelyn Monroe
E is 2.7182818284590.... E is the base of the natural log like 10 is the base of the log function.

Moderator
Virtual Tour: The next best thing to visiting Fermilab in person. http://www.fnal.gov/pub/about/tour/index.html

JonathanRoss
Then where is it that our current understanding of the universe divides into multiple segments? Why is there a hoopla about the need for a theory of "everything?"

Don Lincoln
Let me take a stab at your question, but I don't quite understand the first part. The second part is a bit easier.

buggblue
I am a 7th grade student. What is your educational background?

Jocelyn Monroe
I am a graduate student. I went to grade, middle, and high school on the south side of Chicago, then went to college at Columbia University in New York. I'm still at Columbia for graduate school, and I'm doing research towards a Ph.D. in high energy physics at Fermilab.

Moderator
Fermilab's education office is a great place for our young physicists out there to learn more about physics: http://www-ed.fnal.gov/

Moderator
This is how some seventh graders described physicists after visiting Fermilab: http://www-ed.fnal.gov/projects/scientists/

Matt
Okay. Now on the decimal side, the number continues to descend. Is that correct?

Jocelyn Monroe
No, e probably goes back up again if you look at enough digits. You can get it on a calculator if you take the inverse ln of 1. You might need a really big calculator screen to see more decimals though!

Moderator
Fermilab has VideoNews and streaming video of lectures and colloquia. Here is the url: http://www-visualmedia.fnal.gov/VMS_Site/s_videostreaming.html

Don Lincoln
We study the world around us for a number of reasons. Knowledge is power, as evidenced by our ability to tame fire, smelt metal, make radio waves, etc. So there's a selfish reason to understand the world. But in addition there's the more noble reason, but advancement of knowledge for knowledge's sake. Most of the scientists I know are interested in how the universe works, because the question itself is intrinsically interesting.

Moderator
Here's another great High Energy Physics site: http://particleadventure.org/particleadventure/

buggblue
What is your favorite part of being a scientist?

Don Lincoln
Hi buggblue....Jocelyn answered your last question, but I thought I'd add my two cents. Being a scientist is one of the most rewarding occupations one can have. I'm a super curious person and I get to indulge that curiosity all the time. I get to answer questions and find out answers. My job is always different. I get to build apparatuses, analyze data, ask questions and answer them. Occasionally, I discover something and for a short while, I'm the only person in the world who knows the answer. And that is about as much fun as fun can be.

Moderator
Search all of the different education programs that Fermilab offers: http://eddata.fnal.gov/lasso/program_search/search_programs.html

Matt
What I mean is, as the decimal "grows" does the number actually become less and less in value?

Don Lincoln
The number on the decimal side actually can only add to the number. For instance, consider a number that doesn't repeat, like 3.2... any number after that, say 3.24 is bigger than 3.2 (since it's 3.2+0.04). So the number grows with increasing digits.

Jocelyn Monroe
Hi docv, sorry this is taking me so long. One site is http://psrc-online.org - they have a demos and labs link. Another that has been recommended to me by a high school teacher who works on MiniBooNE is the PIRA 200, which is a list of the top 200 demonstrations. The url is http://www.wfu.edu/physics/pira/pira200/pira200.htm. Another site that might be useful is the teacher on my experiment's home page - he has built a few neat classroom experiments. His page is at http://home.fnal.gov/~bugel. You might look under the link "of interest to teachers." Hope this helps!

Moderator
Here is a recipe for building your own particle detector at home: http://www.fnal.gov/pub/inquiring/questions/homemadepdetector.html

buggblue
Do you have any suggestions for a 7th grade science fair project?

Don Lincoln
Hi buggblue...what sorts of things interest you? I can think of lots of physics projects...only some are particle physics. Give me some idea of your interests, and I'll be a bit more help.

Kiram9
What kinds of internships does Fermilab have for high school students?

Moderator
Hi Kiram. We are working on your question right now.

buggblue
I am interested in electricity and gravity.

Moderator
These are some programs that the education center offers for high school students: http://eddata.fnal.gov/lasso/program_search/calendar.lasso

Don Lincoln
Hi buggblue...while you're thinking about what you might find interesting, here's a really neat thing you can do. You can build a cloud chamber and look at cosmic rays from outer space. (Look at the web site http://w4.lns.cornell.edu/~adf4/cloud.html). This allows you to build a real particle detector. Then you could do something like see how one can shield the cosmic rays (say put the cloud chamber on the surface of the earth and then again in a basement). You could see if the rate of cosmic rays is different above and below ground. (BTW, the nobel prize this year was awarded for this sort of studies).

matt
Thank you, Don. Which side of the number do you like better... the 3 or the craziness on the other side? I'm on the side of the big 3!

Don Lincoln
Craziness is good. It keeps us sane. I vote for the mess.

Moderator
Kiram, here is a website to our employment office at Fermilab. They will have information about internships at Fermilab. http://fnalpubs.fnal.gov/employ/index.html

JonathanRoss
I'm Sorry, Don. I misphrased my previous question. Einstein said, "The grand aim of all science is to cover the greatest number of empirical facts by logical deduction from the smallest number of hypotheses or axioms." My question was meant to be in what groups are our current axioms separated into and why can't they be combined to make a single Theory of Everything? I hope that makes a bit more sense.

Don Lincoln
Hi JonathanRoss....We have a theory that we call the "Standard Model", which is a patchwork of interesting theories that, taken together, do a good job explaining the world we know. Basically we know of four forces, of which we can explain some of their behaviors. (continues)

Moderator
Fermilab has a big audience that visits the lab for cultural events. On this page you can see what we offer: http://www.fnal.gov/pub/events/culture.html

Moderator
Kiram, I also recommend contacting the education office. That is the best place for high school students to get involved with Fermilab. http://www.fnal.gov/pub/education/index.html

Don Lincoln
(continued) We know of gravity of course, which is really pretty tricky to deal with at the quantum level (read that "we don't know how") although we understand it pretty well at the "big (i.e. not atomic)" level. But there are other forces, for instance the electromagnetic force, which causes static electricity and (I am sad to say), is responsible for MTV (although it also works for PBS, so it can't be all bad). The electromagnetic force keeps atoms together and is responsible for chemistry (continued)

buggblue
Do you know any experiments that have to do with plants or animals? If not that is okay.

Don Lincoln
You could drop a cat...but I don't want PETA to get mad at me. Regarding other stuff, I'm not a bio type. I always wanted to do a psychology experiment, where you train your dog to ring a bell or something. That would be pretty cool. It's been done before, but you could do it on several dogs and try to understand the differences. You could compare different animals too.

Moderator
The Birds at Fermilab site is at: http://www.fnal.gov/pub/about/campus/ecology/wildlife/birds.html

Moderator
This is a resource about the prairie at Fermilab: http://www-ed.fnal.gov/data/life_science.html

Don Lincoln
(continued) another force is the strong force, which keeps protons and neutrons in the nuclei of atoms. The next force is the weak force, which, even though its name is weak, powers the sun and causes volcanos. We are able to understand all of these forces. However, there are plenty of mysteries too and that's why we continue to explore. Does this help?

Matt
I have another question... have you ever heard of E.L.F. (extremely low frequency) waves? I read once that they were used by the soviets during the cold war to mess with our heads. I also heard that they cannot leave the earth's atmosphere like other waves because they are just too long. Do they dissapate, or are they still traveling around??

Jocelyn Monroe
I've never heard of E.L.F., but it is true that some waves cannot penetrate the earth's atmosphere. The absorbtion of radiation (waves) is frequency (or energy) dependent, For example, AM and FM radio waves have different frequencies, and so on a cloudy day, you may get more static in AM than in FM. This happens because the waves of a certain frequency may get partially absorbed and be reflected back towards the earth off the cloud layer.

Moderator
Speaking of E.L.F.s: http://www.fnal.gov/pub/inquiring/questions/elf.html

Moderator
Learn about audio waves and radio waves: http://www.fnal.gov/pub/inquiring/questions/waves.html

kiram9
I found plans for building a scanning tunneling microscope and I was wondering what effect atoms in the air would have in the images? Can you get an air molecule stuck between the probe and the test object?

Don Lincoln
Hi Kiram...Typically one builds a scanning tunneling microscope in a vacuum. Otherwise, too much electrical current would flow and the thing would self destruct.

Moderator
Learn about butterflies at Fermilab: http://www.fnal.gov/pub/about/campus/ecology/wildlife/butterflies.html

Matt
Hee! Hee! But three is such a powerful number! If you put them face to face, they make an eternal 8 (just kidding!) But for real, God comes in a 3 (the trinity). I worry that the other side will lead to nothing, don't you? I have an idea for Lederman's T-shirt.

Don Lincoln Matt...The road to perdition starts with a single number. You should probably stick to the left side of the decimal place.

Moderator
Here's a page of Frequently Asked Questions about Fermilab: http://www.fnal.gov/pub/about/faqs/index.html

Trish
why do radio waves sometimes go out when you are in tunnels? Is the cement able to stop the incoming waves?

Jocelyn Monroe
That's exactly right- if you are deep enough underground, or inside of a thick concrete tunnel, the radio waves can be absorbed. The distance that an electromagnetic wave (like a radio wave) can go in a material before it is stopped is related to the energy of the wave. So under enough shielding (like concrete or dirt if you are underground) all electromagnetic waves can be stopped.

Buggblue
What college did you go to Jocelyn?

Jocelyn Monroe
I went to Columbia University for my undergraduate degree. What colleges do you think you might want to go to? I highly recommend Columbia!

Matt
I understand that waves are sent and that they carry signals. Can they be sent without signals? Are the signals made of electricity? Are the waves seperate from the signals?

Don Lincoln
Waves, in this context, are variations in the electric field. You can certainly cause waves to go without sending information....just like you can make waves in water without sending information.

Elle
I sometimes ride my bike through Fermilab and have noticed a big blue piece of equipment along Batavia Rd. What is it?

Moderator
Elle, that big blue piece of equipment is the Harkins Cyclotron. It was used by Enrico Fermi and other physicists at the University of Chicago to study Neutron Diffusion. It was built by William D. Harkins with the help of some students in 1936.

Moderator
On this webpage you can see Live Events from the detectors of CDF and DZero. http://www.fnal.gov/pub/now/live_events/index.html

Moderator
Learn more about Jocelyn's experiment, MiniBooNE: http://www-boone.fnal.gov/

Guest
What has been discovered as the smallest particle? How can one prove it?

Don Lincoln
There are two types of particles that are so small that we don't know how small they are. These are the quarks and leptons. We try to measure their size and we find that they are smaller than we can measure. We know we can measure something ten to the minus 18 meters. So they're smaller than that. But I don't know their size. We do this by smashing atoms together. The more energy, the closer we can smash them. From that data we can infer the size.

Moderator
Learn more about Don's experiment, DZero: http://www-d0.fnal.gov/

Moderator
Curious about those small particles? http://www.fnal.gov/pub/inquiring/matter/smallest/index.html

Matt
You are very helpful, Don Lincoln. Thanks. Can electrical information get stuck on empty waves that are already floating around in the air?

Don Lincoln
Information is a tricky thing. In many ways, electrical waves are like voice waves. You can hum, which doesn't convey much information, unless you tell someone that if you're quiet it means one thing and if you hum, it means another. Speaking causes much more complex waves and can convey a correspondingly greater degree of information. Waves that are floating around can be generated from natural or man-made sources, so they may or may not convey information.

Moderator
Here are some discoveries that have been made at Fermilab: http://www.fnal.gov/pub/inquiring/physics/discoveries/index.html

Moderator
Here is a hot topic: Neutrino physics at Fermilab - http://www.fnal.gov/pub/inquiring/physics/neutrino/index.html

Beela
What are you working on recently at Fermilab?

Don Lincoln
Let me grab that one....I'm working on D0 (www-d0.fnal.gov), while Jocelyn is working on MiniBoone (a neutrino experiment). People at Fermilab work on many experiments. It's really an intellectually thriving place. Everyone here is trying to understand the world at the most fundamental level.

Beela
What proof is there that gravity really does exist?

Jocelyn Monroe
The proof that gravity exists is that you don't fly off the earth when you walk around! Newton had the idea for gravity because he watched an apple fall (or maybe it hit him in the head) and started to wonder why it went down and not up. More precise tests of the strength of gravity are being done all the time. Many of these experiments use an apparatus called a Cavendish Balance. A computerized version is shown at http://www.telatomic.com/attractive.html. There is an experiment called LIGO that is looking for gravity particles! They haven't found any yet though.

kiram9
http://www.geocities.com/spm_stm/Project.html This person seems to have a scanning tunneling microscope, which operates without a vaccum

Jocelyn Monroe
Hi Kiram9, that scanning tunneling microscope looks really neat! Thanks for sending the link.

Moderator
On this webpage we post accelerator updates: http://www.fnal.gov/pub/news02/update.html

Moderator
QuarkNet is a research collaboration between high school students, teachers and particle physicists. This is the QuarkNet website: http://quarknet.fnal.gov/

Matt
Also, is a circle exactly 360 degrees, or is there a little space left over in between the beginnng and the end of it? I heard once that there was a little bit left over in there. Is that true?

Jocelyn Monroe
By definition, 1 degree is 1/360th of a circle, so there have to be exactly 360 degrees in a circle. Nothing left over, at least in this dimension.

docv
Thanks for the high school resources. Last question for me, what do experimentalist do to minimize errors in collecting data from all the wires and multiplier tubes associated with particle detectors? I'm thinking about magnetic shielding, faraday cages, and even cooling down amplifiers to minimize electronic noise...any others??

Don Lincoln
Basically what you try to do is to get control of your equipment. If you know that electrical noise is a problem, you try to wrap your detector in conductive material to shield it. If there is a problem with noise because the detector is too hot, you cool it. One by one, you go try to fix every problem you find. There's a lot of possible sources of error...simple things like just making sure your detector is in the right place. If you had a stretchy ruler, you could measure things wrong. So there are lot's of things.

Moderator
What is the Tevatron doing right now? Check the Tevatron status: http://www-bd.fnal.gov/servlets/d11?project=outside

Matt
So from what you know, could telepathy be real?

Jocelyn Monroe
I'm going to go with no. But there are other opinions out there.

Moderator
Physics is our mission, but buffalo may be Fermilab's main attraction for visitors. What are buffalo doing at a physics laboratory? Here is the answer: http://www.fnal.gov/pub/about/campus/ecology/wildlife/bison.html

Moderator
Learn more about the Standard Model: http://www.fnal.gov/pub/inquiring/matter/ww_discoveries/index.html

Matt
Good answer regarding the circle, Jocelyn. I'd go with no on the telepathy also.

Don Lincoln
I knew you were thinking that.

Beela
How do you think knowing about things we can't even see helps us?

Don Lincoln
Well, let me turn that around...can you see a virus? (The answer is no, but it can still kill you.) You can't see an electron, but it allows your computer to work. There are many things that you can't see that are enormously useful.

Moderator
Reasons to support high-energy physics: http://www.fnal.gov/pub/inquiring/matter/whysupport/index.html

Bella
When will transcripts of this be available?

Moderator
Beela, transcripts of this session will be available sometime in the next couple of weeks. Check back at: http://www.fnal.gov/pub/inquiring/virtual/

Don Lincoln
Continuing on things that you can't see, you can't see air, yet you breath. You can't see atoms, yet the chemistry of eating is pretty cool...especially if someone bakes the right kind of cookies. I would say that in general, knowledge is power.

JonathanRoss
Actually it helps quite a bit, I'd heard the words standard model before but didn't know that was something particularly important (you don't hear it quite as often as Special/General Relativity or Quantum Mechanics). Also, agreed about MTV although I'm for Junk Wars on TLC (even if this season it's become a bit less building and a bit more racing). But this leads me to my second question which was going to be about gravity but first let me make sure I understand why I'd need to ask this question by a doing a little pre-question probing :) I'm having a conceptual problem, if a particle (subatomic) is only “likely” to be somewhere, then what is a molecule? Is it really a molecule or is it a hang out where one of it's subatomic particles is just likely to be? Sorry I took so long to follow up but I wanted to make sure my question made sense before I asked someone else (as we can't exactly read minds)it.

Jocelyn Monroe
Basically you are right- a molecule is kind of a hang-out where the atoms are likely to be found in the sense that most molecules are bound together by electromagnetic interactions between the electrons attached to the constituent atoms. And since you can never localize a particle (i.e. know its position and momentum to arbirary accuracy at the same time) you can't say exactly where any of those electrons are at any given time, you can only say that some locations are more probable than others. The protons are basically stationary, since they are so much heavier, but it is still true that you cannot pin them down exactly.

Moderator
Fermilab's art gallery has regular shows: http://www.fnal.gov/pub/Art_Gallery/

Moderator
Fermilab offers limited recreational access: http://www.fnal.gov/pub/news02/access.html

Beela
Don, Lincoln....That's true about the things we can't see. It's an interesting point.

Don Lincoln
Thanks...

Moderator
A recent Fermilab press release: http://www.fnal.gov/pub/presspass/press_releases/rocky.html

Moderator
Subscribe to FermiNews - http://www.fnal.gov/pub/ferminews/web_signup_fnews/sign_up.html

JonathanRoss
Ahhh, ok, so then I have one last precurser question to my final question (I'm glad English is a logic laden language or else I'd sound silly right now). I'm not sure about this, but I've heard that particles arn't always there, that some just appear out of no where (the small ones that decay), etc., etc. If this is true are the particles in a molecule always there or do they decay and get replenished?

Don Lincoln
What you're talking about is really a very cool consequence of quantum mechanics and something called the uncertainty principle. It allows for pairs of matter and antimatter particles to be created briefly, before they recombine back into energy. Thus at the subatomic level, the universe looks a bit like foam...particles are continuously being created and destroyed.

Moderator
Just what is the world made up of? http://www.fnal.gov/pub/inquiring/matter/madeof/index.html

Don Lincoln
Continuing on with Jonathan's question. In a molecule, there are particles that stay around on average...for instance the electrons and the nucleus of the atom. However, in addition there are these "virtual particles" that I described earlier. The world at the quantum level is a really lively place.

Janet
How many varieties of Quarks are there, and how are they named?

Jocelyn Monroe
Hi Janet, there are 6 quarks, and they are named up, down, strange, charm, bottom, and top, in order of lightest to heaviest. The bottom and top quarks were discovered at Fermilab! The last two were named truth and beauty before they were found, but somehow those names fell by the wayside. Too bad...

Moderator
Here's another great High Energy Physics site: http://particleadventure.org/particleadventure/

Moderator
Learn about accelerators at Fermilab: http://www.fnal.gov/pub/inquiring/physics/accelerators/index.html

Beela
Just out of curiousity, how do they work the atom smashing procedure you mentioned earlier?

Don Lincoln
You accelerate the particles using electric fields (your television is an electron accelerator). When the particles are moving quickly enough we aim that at one another...just like billiard balls. From how the particles react, we infer a lot of information about the nature of the particles and the forces that they feel.

Moderator
Here is some information about technology at Fermilab: http://www.fnal.gov/pub/inquiring/physics/technology/index.html

kiram9
I have another question. In the particle accelerator how are neutrons accelerated since they have no electrical charge?

Don Lincoln
Excellent question. Typically what one does is accelerate protons and aim them at a target. The protons knock out neutrons that then have high energy. Those accelerator physicists are pretty tricky...

Moderator
Ever want to accelerate a proton? This is how: http://www.fnal.gov/pub/inquiring/physics/accelerators/accelerate.html

Moderator
Interesting facts about Fermilab: http://www.fnal.gov/pub/about/faqs/index.html

Moderator
Here are some programs for graduate students at Fermilab: http://eddata.fnal.gov/lasso/program_search/grad.lasso

Janet
Why are electron orbitals given the designations s,p,d,f? What do they stand for?

Don Lincoln
I believe the designation spdf stands for spherical, polar, dipolar and beats the heck outta me. These reflect the shapes of how the orbits swarm around the atoms. A spherical distribution of electrons has (surprise) a spherical shape. Polar orbitals kind of look like a figure-eight. Dipolar, is like two figure eights. F I can't help you with.

Moderator
Luminosity in the Tevatron keeps going up,up,up...http://www.fnal.gov/pub/now/tevlum.html

Janet
If the nucleus of an atom is positive, and the electrons are negative, why don't they attract each other?

Jocelyn Monroe
They do attract each other, but the "repulsive forces of quantum mechanics" are stronger than the electromagnetic force of attraction. What I mean by "repulsive forces of quantum mechanics" is that Niels Bohr predicted that angular momentum (that is the momentum associated with rotating objects) comes in discrete units, called quanta. Like regular momentum, angular momentum is conserved. But since it only comes in discrete units, the electron cannot fall out of its orbit towards the proton. So, the electron has no where to go but up! And this can only happen if some other interaction occurs, since angular momentum has to be conserved. A classical example of this is the planets - they revolve around the sun and don't fall out of there orbits, although they are attracted by gravity. This is also due to conservation of angular momentum.

Matt
How do I get my T-shirt idea to Lederman? He said in his book that he wanted a way to explain everything simple enought to put on a T-shirt. I have one that's simple as pie. Don't try and steal it...

Don Lincoln
You could send it to the Fermilab Office of Public Affairs. I'm sure that they would give the idea the proper response.

buggblue
What other subjects do you like besides science?

Don Lincoln
I'll tell you, if you tell me how you get such cool icons....

buggblue
If you were not a scientist, what would you be?

Jocelyn Monroe
If I was not a scientist I would like to be a billionaire! Or a chef, or a violinist, or a journalist. What about you?

kiram9
Okay. Then how are they detected if there is no charge? (I understand that most particle detectors rely on electric charges) or do they just do the opposit of accelerating them (crash them into a plate and see what pops out?)

Don Lincoln
You are absolutely correct. Most particle detection relys on "ionization", which is an electrical interaction. But remember that there is also the "strong interaction" which a neutron actually feels. The neutron bumps into the nucleus of an atom and can do all sorts of things, from knocking out a proton (which we can detect using the electrical charge), or its energy can be converted into matter (good 'ol E=mc^2) and make lots of particles we can subsequently detect.

Moderator
Here is a reading list of high-energy physics books: http://www.fnal.gov/pub/ferminews/reading.html

Moderator
Learn about the architecture at Fermilab: http://www.fnal.gov/pub/about/campus/architecture.html

Beela
Hi! Is the electron cloud theory the best and last one on electron form or do you think that there may be a better theory that could be created, since we've moved on from the plum pudding theory and others in the past?

Don Lincoln
I don't know. That's why we do experiments. However, I can say that it works >>EXTREMELY<< well. But I can't guarantee that our next discovery (Nobel Prize, here I come) might show that it's wrong. But my best guess is it does a good job of explaining things, so it can't be too wrong.

Moderator
Director Michael Witherell's vision for the lab: http://www.fnal.gov/pub/about/directorsoffice/index.html

Moderator
Fermilab has a new lecture series about astrophysics called Starry Messages: http://www.fnal.gov/pub/events/starrymessages.html

buggblue
So what other subjects you like besides science?

Don Lincoln
I like lots of things. I'm interested in history, and anything that lets me better understand the world in which we live. History, for instance, explains a lot of current events. Seeing how people work (psychology) is also interesting. Basically, give me a mystery and I'm there....

Guest
It can create matter!!! Voila, just what I wanted. Now I can erect solar panels and build myself a car for free!! Heh, oh I need too much energy? Darn! Are there any other better ways to make matter (apart from fusion)?

Jocelyn Monroe
Fusion changes one kind of matter into another. You can take two atoms and smash them together to make a different kind of atom. Fission is a way to split one atom into different, smaller pieces. But I wouldn't say that fission is better, fission gave us Hiroshima and Nagasaki. But fission has also given us nuclear power plants, too, so it is useful ...

Beela
Okay. This is my last question before I gotta go. I've heard about the formation or possible formation of black holes in the lab, but is it a hazard? What is that about?

Don Lincoln
Here's a quick answer. No...it's not a danger. Cosmic rays from outer space of enormously greater energy hit the earth all the time. We're still here....ergo, no problem. But a lot of people worry about it. Luckily, the cosmic ray answer proves that this isn't a bit of a problem.

Moderator
Here is some information about black holes: http://www.fnal.gov/pub/inquiring/questions/blackholes_info.html

JonathanRoss
Ok, then my final question is... Gravity supposedly has no abberation, everything that does react to gravity reacts to the gravity of everything else instantly (or so close to instantly it can't be detected). If particles seem to pop in and out of existence and for some reason do so around a center of gravity. When you pluck a guitar string it looks like the entire thing is pulled up. If you plucked it at two points the two waves then overlap, it takes time for a wave to propagate on a string, but it takes almost no time for peaks to pop up. So why can't I say gravity emits particles rather than particles emit gravity, that particles are really just peaks of a really big wave?

Don Lincoln
To begin with, we believe that gravity does not affect everywhere instantly. In fact, if the sun were somehow to disappear (don't ask me how), we wouldn't know about it until 8 minutes later (the same amount of time it takes to notice the lights went out). (continued)

Moderator
Sign up for the Interactions high-energy physics news wire at : http://www.interactions.org

Moderator
Kiram, your last questions was answered while you were out. Be sure to check back for the transcript.

Don Lincoln
(continued) The thing about gravity is that we don't know how much about it (quantum mechanically). We only know of Einstein's theory (circa 1920 or so). We speculate about particles called gravitons, but they haven't been discovered. Regarding Einstein's theory, two particles both create a magnetic field and a person can feel the effects of both (for instance the earth, sun and moon). In that sense, the gravity can add like waves.

Janet
When will you offer another Ask-a-Scientist event? I want to tell my students.

Moderator
Janet, we will probably have chat sessions every month or so. Please check back at http://www.fnal.gov/pub/inquiring/virtual to find out when the next session will be.

Janet
Do particles more energetic than neutrinos exist?

Jocelyn Monroe
The most energetic particles ever detected are cosmic rays (this can be any kind of paricle, the name cosmic ray just means that it comes from space.) These cosmic rays have energies up to 100 million times as large as the most energetic proton beams at Fermilab! We don't know whether these cosmic rays are protons or neutrinos or some other kind of particle.

Moderator
We are wrapping up our chat session now. Please submit your last questions now.

Moderator
Please be sure to check out the Virtual Ask a Scientist website to find out when the next chat session will be!

Moderator
Read the latest issue of Ferminews: http://www.fnal.gov/pub/ferminews/ferminews02-10-04/index.html

kiram
Regarding the gravity detector, could a person use that to detect localized gravity disturbances from people or "antigravity devices"?

Jocelyn Monroe
The LIGO experiment is trying to do exactly this! They will be able to detect the gravity waves from a supernova (if one occurs.) So they are trying to detect a localized gravity disturbance. Their webpage is at http://www.ligo.caltech.edu. Check it out!

JonathanRoss
But does gravity arrive in packets, can it cancel out and amplify in alternation like electron or electro-magnetic waves? Or is it purly a wave? Also, if gravity has an abberation is it accounted for in astrophysical calculations or is it so much faster than the speed of light it can be ignored?

Don Lincoln
We don't know if gravity arrives in packets (although we collectively suspect that it does). However, unlike the electromagnetic force, gravity only attracts and that's an important difference. Two sources of gravity can cancel each other out, if they are on opposite sides of you, but that's it. Gravity travels, to the best of our knowledge, at the speed of light. That's why if the Sun disappeared, we'd find out that from the earth spinning off into space at the same time that the lights went out. Luckily, this is unlikely to occur, so it's only a theoretical experiment.

buggblue
Good by and thank you for your help.

Moderator
Thanks to everybody who joined our chat session! It's been a great a session. Please check back for the full transcript in about a week or so.

Jocelyn Monroe
Good night! Thanks for all your questions- come back next time!

Don Lincoln
I'd like to chat more, but the meany Chatmaster says we can't. It's been fun. Come back next time....

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last modified 10/25/2002   email Fermilab