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>The Wikipedia has a "computer bug" entry that lists some other "famous bugs" including the fictional HAL 9000 bug.

Yeah, it lists them, but doesn't really link to good stories -- so...

An error in a single FORTRAN statement resulted in the loss of the first American probe to Venus.

Software reboot during the Apollo 11 landing forced Armstrong to manually land the lunar lander.

An Iraqi Scud missile hit Dhahran barracks, leaving 28 dead and 98 wounded. The incoming missile was not detected by the Patriot defenses, whose clock had drifted .36 seconds during the 4-day continuous siege, the error increasing with elapsed time since the system was turned on. This software flaw prevented real-time tracking. The specifications called for aircraft speeds, not Mach 6 missiles, for 14-hour continuous performance, not 100. Patched software arrived via air one day later.

The Ariane 5 satellite launcher malfunction was caused by a faulty software exception routine resulting from a bad 64-bit floating point to 16-bit integer conversion.

lots more here and here.

A friend of mine is starting into what looks like a promising career in scriptwriting. He's been paying his dues writing kiddie movies, and now he's doing his first sci-fi horror flick. Having spent a lot of time hanging around engineers when he was at university (he wrote for their humour rag) he decided to put a good deal of thought into the script. Not only did he consult people to find out what they liked/disliked about the sci-fi horror genre, but he also did a bit of research to ensure that the "sci" part didn't take too far a backseat to the "fi" part. Within reason, of course, but he did make an effort. For his troubles? The producers congratulated him on bringing them a thoughtful, edgy, well researched script, and then immidiately asked him to have more stuff (like inert barrels) blow up real good so that the movie would be more "explosive." This would mean cutting out some of the neccessary "sci" background. It seems that most audiences don't mind checking their brains at the door, and producers want to sell tickets, not educations. Go figure.

C'mon up to Canada for your education. The tuition is about half (or less) of what it is in the states, if you're gay you can get married, and we're about to decriminalize marijuana.

Better yet, you don't have to pay to see our rankings:

1 Toronto
2 Queen's
*3 McGill
*3 Western
5 UBC
6 Montreal
7 Alberta
8 Sherbrooke
9 Ottawa
10 McMaster
11 Dalhousie
12 Saskatchewan
13 Laval
14 Calgary
15 Manitoba

Is this a stupid analogy or what? This can be said about any type of light detector. This is like saying a digital camera works like a light bulb in reverse... duh? So these "modules" are just simply really sensitive digital cameras networked together.

Not quite. These are photomultiplier tubes, designed to detect single photons. A photon strikes a photosensitive material, generating an electron. This electron is accelerated down a high-voltage tube, knocking additional electrons free from electrodes, creating an electron cascade that can be detected.

The electron cascade may or may not be detected using camera-like photosensors (using a phosphor screen to turn the electron cascade back into light) (nightvision goggles do something like this, photon-counting tubes may measure the charge transfer directly).

When I first read about these things I thought it had something to do with solid glass spheres that for some reason, in combination with the ice, had optical properties that allowed them to capture neutrinos.

Ice is used because it's reasonably transparent. That's about it. Neutrino detection in this detector seems to be purely based on scattering of neutrinos against other particles with enough energy to produce Cherenkov light as the other particles fly off. How they plan to focus exclusively on muons is beyond me. With electron neutrinos you'd mainly get electron scattering as opposed to direct synthesis of muons. While mu neutrinos could produce muons via Weak-force interactions, they'll have scattering interations as well, and you have plenty of electron neutrinos present too.

A good introduction to neutrino detection is at http://www.sno.phy.queensu.ca/sno/sno2.html (Sudbury Neutrino Observatory page).

No, they're just cameras. Why make it sound more complex than it really is?

Cameras produce images. Photomultiplier tubes don't (they just indicate that a photon hit the tube). Determination of the path of the neutrino is done by looking at the timing of photon events in many detectors in the array, and looking at which detectors registered events at all.

According to this site: Wikipedia, Cruithne is an asteroid that shares Earth's orbit about the Sun, but doesn't actually orbit Earth. This site has more technical information.

Mars has a co-orbital asteroid and Jupiter has 400 captured asteroids, but they aren't considered moons. They are just asteroids, as is this one.

So in my opinion, since this is just an asteroid of small size and it doesn't truly orbit our planet, it shouldn't be called a moon.

Actually, I heard that on the radio (NPR), so I just googled it and came up with 10 watts. I'll take neither of these answers as definitive ;)

can't believe no one brought this up yet. Recently some astronomers have been using hubble to look at the middle of galaxies and have discovered Supermassive Black Holes [thehubbletelescope.com] there. In fact, they've found a bunch of 'em, and there's a relationship between the size of the galaxy and the size of the singularity, and every galaxy seems to have one, even our own! And IIRC they figured this would account for the missing stuff.

Well, as far as I understand, that's some missing mass, but not nearly enough. More importantly, it's not the right distribution to explain the velocity curves. I did some googling (you can do some more if you like) and found this page. I'm sure theres better ones out there but it appears to be pretty accurate. This is not simply a problem of having enough mass in the galaxy, but having enough mass in the right places... The velocity curves of stars in different galaxies of the same mass provided that the mass is distributed differently. The curves we get are rather consistant with a spherical halo of dark matter (yes there's other theories but this is simple to imagine) which acts much different than a point mass at the center of the galaxy. This can be seen by the fact that anything inside a spherical shell of matter feels no net gravitational pull. for instance, if the earth was a perfect hollow sphere, on top of it you'd feel plenty of force, but go inside of it, and the forces from all directions cancel out. Same with a spherical halo of dark matter, stars only "feel" a force from the dark matter in the part of the halo that has a radius smaller than their orbital radius, the rest cancels itself out. This makes a significant difference in the measured velocity curves, and these curves do not point to dark matter simply being a point source in the center of the galaxy.

So I don't really think that discovery is that relevant to this discussion. Cool? Yes. But doesn't come close to explaining the mystery that is dark matter. (Yes, I'm aware of various modifications to gravity theory that could also explain this as well)

Cheers,
Justin

Disclaimer: I am not a physicist yet (still one more year to go before my degree). I do however have published research in astrophysics, as I do research with two respected astrophysicists here at Cornell University. If I've made a mistake anywhere in my reasoning here, someone please correct me :)

Russian Tea HOWTO
Linux and tea ... mmmmmm!

I've actually been working as an undergrad assistant in a lab at UT Austin that is very active in the MINOS consortium, so it's pretty cool to see the experiment getting some attention.

There are some neat photos of the detector; the steel scintillator modules weigh about 5,000 tons (!), and you can see one as it is lifted into place. The detector uses something like 2000 16 channel photomultiplier tubes (I don't remember the exact number of tubes) to detect the showers of particles that are created as neutrinos interact with the steel scintillator plates, and the data from those tubes is processed to reconstruct events. Did I mention that the whole thing is in a cavern about 1/2 mile underground to reduce background noise from cosmic rays?

The detector is supposed to come online and start collecting real data in 2004.

Another very interesting neutrino experiment is SNO, the Sudbury Neutrino Observatory, which is in an underground mine in Canada. SNO resolved the solar neutrino problem; people previously couldn't explain why we weren't seeing the right number of neutrinos coming from the sun - it turns out that they "oscillate" and change into other types of neutrinos, and SNO verified this. The neutrino oscillations also imply that they have a non-zero mass (explanation beyond the scope of this comment ;)

The point of MINOS is to observe neutrinos from a controlled high-energy accelerator beam, rather than whatever we get from the sun, to very accurately measure the oscillations.

I kid you not, when I was a T.A. in grad school, a student once handed in a paper where they said "foo foo foo, intern bar happens"! Yep, "intern", like Monica Lewinsky. This person had graduated from high school with decent enough grades to get into the biology program at one of Canada's top universities :-P

(Also an example of the perils of relying on spell check! Though I hope that would at least catch "insundry"...)

In high rez http://progressive.stream.aol.com/wb/gl/wbonline/p rogressive/thematrix/us/med/animatrixlgfinal_dl.mo v
or here http://engsoc.queensu.ca/jabela/filez/videos/anima trixlgfinal_dl.mov

Here, here, I second this motion (even though I'm on the outside looking in, as a Canadian). I always think of Freeman Dyson's book Eros to Gaia when it comes to politics and science; you can't try to fund just the "good" or "popular" science. Try and keep big politics out of science. Science has enough internal politics, it doesn't need any outside help!

So how much more dark matter must we account for to get the right Omega value?

Queen's University recently introduced a program in Biomedical Computing and has discovered a much better gender ratio of applicants than its regular Computing Science program. Obviously we believe this is due to the greater human involvement. Therefore: if you want women in CS, make it squishy!

(Checkout my expired domain search engine script at http://datacracker.com/expireddomain/)

(Checkout my expired domain search engine script at http://datacracker.com/expireddomain/)

Shouts outs to Jeff, Alex, Ryan, Changuk, Roel, and Edwin!

It is lucky that our URL does not appear in the body of the article or the cube would have been slashdotted! :-)

Wondering if this study could shape some ideas in driving Video Conferencing technology - I know from my experiences the most offputting aspect of participating in VCs is people not looking at you while talking, due to the locations of monitors and cameras not synching.

As an aside, why was the link from the main page to the ScienceDaily web site, when the article clearly has a link to the original from Queens University ????

It seems to me that since the cosmologists have been working hard since the Big Bang theory was first proposed to work out the manner in which this universe (lets start by not assuming its the only, or one of many, but just...here) came into being. This has worked out well with many other fields since both ends of the spectrum, quantum and astronomical, have been feeding back more solid information (be they constants or otherwise) to "keep the cosmologists on track". But it seems in just the last 5 or so years, the facts about what we *don't* know about the universe are begining to make the theories of cosmology a bit out of touch.

For example back in 1998 when studies of distant supernova gave thorough evidence of an increase in the speed of the universes expansion. Now, this one still seems to be giving headaches to most all the theorists, and it seems to me that working around, or flat out ignoring that fact when building the "big theory" leaves a bit to be desired. Now enter Dark Matter. The lack of a comprehensive understanding of either A) the particle composition of the universe in the order of about 88% or B) an understanding of gravity to a power of 10 gives us yet another piece of the puzzle we're basically clueless about. Now, I understand that the purpose of these kinds of theories is just that, to test out hypotheses against what we do have in terms of fact and go from there, but it seems like maybe we should shelve the Big Theory Of Everything and work a little harder on the Theory of Very Specific Things That We Know We Don't Know.

That being said, IANA(astromomer/cosmologist/physicist) so please, jump down my throat and tell me what *I* don't know because I for one am willing to admit that I don't have it all figured out quite yet.

I understand the difference between a satellite and a companion. However Cruithne and this body both follow spiral orbits in resonance with the Earth. Neither body orbits the Earth directly. I wanted to know why 2002 AA29 was described as the "first ever" companion object found when 3753 Cruithne was discovered in 1997, and given the discoveries of 1998 UP1 and 2000 PH5.

See Weigert for more information.

A Trojan asteroid is "any planetoidal body at the triangular Lagrangian point of any two bodies" named thus because the Trojan asteroids of the Sun - Jupiter system are named according to the Illiad.(Wikipedia). There's an interesting webpage on the Trojan asteroids in the Sun - Earth system here

Here is Paul Wiegert's information on Cruithne, which has much of the same characteristic as this current space body, but his explanation actually makes sense for what appears to be a horseshoe orbit, when in reality it's only a horseshoe orbit from Earth's perspective, and is relatively sane looking when viewed off of the solar system plane.

Here is Paul Wiegert's information on Cruithne, which has much of the same characteristic as this current space body, but his explanation actually makes sense for what appears to be a horseshoe orbit, when in reality it's only a horseshoe orbit from Earth's perspective, and is relatively sane looking when viewed off of the solar system plane.

It's known either as Planet X, or a name that starts with N [nemesis]

Try the astronomy pages for an explanation of why this is considered crap.

(p.s. More interestingly, read about our weird 'moon', Cruithne - stranger than fiction!

Specifically, there are two two more near-Earth asteroids known to be currently in resonant states similar to those of Cruithne.

Yes, but from a geocentric viewpoint, the moon's path describes a circle with the earth at the center. From that same POV, Cruithne follows a kind of horseshoe with the sun at the center.

Cruithne isn't really a moon - it's a coorbital companion. And if you look at the Cruithne FAQ fm6 linked to, you'll see that it's not the only one. So if these coorbital companions counted as moons, this new object (if it isn't just a spent rocket booster) really would be the fifth moon.

Does the Earth have any other companions or moons?

Yes, the Moon. But apart from that, there are no natural objects known to be in close dynamical relationships with the Earth. NEW! Asteroid 1998 UP1 and 2000 PH5 have been found to be in similar relationships with our planet. We are currently (18 Sept 2001) working on publishing these results. Look for more info here soon.

Satellites: 4
#1 Moon, average distance: 384,000 km (211,265 miles)
#2 Asteroid 3753 Cruithne
#3 Asteroid 1998 UP1
#4 Asteroid 2000 PH5

The Page of #2 Cruithne's Discover has details on the weird "resonant" orbit of #2. #3 and #4 are from same team, and are equally weird. Note that "Horseshoe orbit" is relative to the supposed primary (Earth) as opposed to the actual primary (Sun) around which the pair are mutually resonant. The previously referenced space.com article said it had a booster-like orbit, implying chaotic, but didn't indicate if it was a ?stable? chaotic orbit, a single-lagrange-point orbit, or a quasi-stable multi-lagrangian horseshoe orbit of a temporary (10kyears) or what.

We dont need no stinking .sigs

The discoverers of Earth's second moon, 3753 Cruithne, announced the discovery of "moons" three and four - 1998 UP1 and 2000 PH5 - almost exactly a year ago, September 18, 2001. See http: //www.astro.queensu.ca/~wiegert/3753/3753.html for more details.

Well, according to your definition of a moon, 3753 Cruithne is not a satellite of the Earth, because it does not orbit the Earth.

Earth's second one is called Cruithne. It was discovered in 1986 and it takes a convoluted horseshoe path around our planet as it is tossed about by the Earth's and the Moon's gravity.

Umm, Cruithne's orbit is a horseshoe around the SUN in Earths orbit. Not around Earth.
The following is taken from Near-Earth Asteroid 3753 Cruithne Frequently Asked Questions

Does asteroid 3753 Cruithne orbit the Earth like a moon or satellite?
No. The asteroid's behaviour is more complicated than that: it doesn't orbit the Earth, but rather it shares the Earth's orbit. The relationship of a moon to its planet is called a two-body because there are only two important players (ie. the moon and the planet). However, in the case of Cruithne, the Earth and the asteroid both share the same orbit about the Sun, but are choreographed in such a away as to remain stable and avoid colliding with each other. This is called a three-body relationship as there are three main players: the Earth, the asteroid and the Sun.

(Sept 18 2001) There are now two more near-Earth asteroids known to be currently in resonant states similar to those of Cruithne. These are 1998 UP1 and 2000 PH5. We are currently in the process of preparing these results for publishing. Look for more information on these fascinating new asteroids soon.

As mentioned above, Cruithe was reported on slashdot previously.

Matt

I'm missing something. I thought a moon was an object that orbited a planet. Cruithne's orbit is profoundly perturbed by the Earth's gravity, but it stil orbits the sun.

The CANDU reactor is NOT a breader/fast reactor.

The CANDU reactor does NOT consume its own plutonium
It is simply a different type of reactor for electricity generation.

References:

Atomic Energy of Canada Limited - Creators of the CANDU reactor design. Corperate homepage.

British Energy - Fact File on Reactor Types

Atomic Energy of Canada Limited - Press release regarding commissioning of new CANDU reactor in China (August 13, 2002)

Bruce Nuclear Power Facility - Tiverton, Ontario.

-legolas.

To the people who are suggesting some kind of calculator, please realize that mathematics does NOT equal +-*/=[0-9].

seven years? newbie! ha!

t.

I had to pick my university to next year, it was primarily between UofW and Queen's. The primary reason I decided to go toe Queen's instead of UW is the fact that UolfW has mandatory CO-OP for all engineering students. With the tech economy at the moment, that was more trouble than I was willing to gamble on.

Although both slung a pile of scholarships my way, but I know now that I made the right decision. Computer Engineering at Queen's is where I'm headed. M$ has yet to take them over.

Actually, Apple File Exchange came with System 6 and would let you transfer a file off of an MS-DOS floppy. PITA to use, but it was Apple Software.

I'd like to see Earth improve its moon count, as we have only one.

Actually, we sort of have two. There's an asteroid called Cruithne that has a curious orbit around the Earth and Sun...

Scientists at the SNO facililty have reported that their detector has sprung a leak!

*Yawn* We knew about it last week. Here's a snippet from the copy released by PR people at Laurentian University in Sudbury:

New scientific results from the Sudbury Neutrino Observatory to be announced

April 18, 2002

(Sudbury, Ontario) - Scientists from Canada, the United States and the United Kingdom, working at the Sudbury Neutrino Observatory (SNO), a unique underground laboratory built to provide insights into the properties of neutrinos and their emission from the core of the Sun, will submit a scientific paper with important new results later this week. They will announce these research findings in a scientific presentation by Dr. Andre Hamer on Saturday, April 20, at the Joint Meeting of the American Physical Society and the American Astronomical Society in Albuquerque, New Mexico. A copy of the first scientific paper and news release summarizing SNO's findings and their importance will be posted on the SNO website (www.sno.phy.queensu.ca) at 1:20 p.m EDT (10:20 a.m. PDT) on Saturday, April 20. A summary talk on the implications of these neutrino measurements will be presented by Dr. John Wilkerson on Monday, April 22, at the same conference.

"We look forward to this opportunity to share these new findings with the scientific community and the general public," says Dr. Art McDonald, SNO Project Director and member of the Department of Physics at Queen's University. "For the first time, we are reporting on an important neutrino reaction in the SNO detector - a reaction in which all known neutrinos participate, regardless of their type. The successful observation of these neutrino signals has been a chief goal of the years of intense work by a collaboration of close to 100 scientists at 11 universities and national laboratories in Canada, the United States and the United Kingdom, and we are very pleased with the quality of the data obtained."

In June 2001, the SNO scientific collaboration announced definitive results based on two other reactions seen in the SNO detector, and on measurements at the SuperKamiokande neutrino detector in Japan, establishing that neutrinos from the Sun change from their original electron neutrino type, to a mixture of electron and other (mu or tau) neutrino types. The new data from the Sudbury Neutrino Observatory to be announced on April 20, enables this question to be addressed accurately from data obtained entirely from SNO, and is expected to enhance significantly our understanding of these important properties of neutrinos from the Sun and of the Sun itself.

Additional information about the conference presentations, the SNO laboratory, the neutrino measurements being made and the participating institutions can be found at www.sno.phy.queensu.ca.

As an ex-member of SNO (my name (N. Tagg) is on the papers) as well as a current member of MINOS (the experiment you're reffering to at Fermilab) I can say that this is simply not true; the experiments are complimentary, not exclusionary.

In fact, there is a large quantity of work going on in this field. Current experiments include KamLAND, Borexino, Opera, NuMI-MINOS, Super-Kamiokande (when they finish their repairs in a year or so), K2K (KEK to Super-K), MiniBOONE the new JHF facility, plus a bunch more I'm forgettting.

There are several reasons for all this activity. First, there are at least two different types of oscillaitions. (The naive and over-simplified theory is that there is nu-electron to nu-mu oscillation, and nu-mu to nu-tau oscillation, the first of which is seen by SNO, the second of which is seen by atmosphereic neutrinos and by the beam experiments). There may be a third mode, which implies a new variety of neutrino (nicknamed 'sterile' for various reasons).

In addition, we're looking to prove that our theory about the oscillations is correct; that they really oscillate in the way we think they do (i.e. change back and forth between flavours on a given time scale that is dependent on energy and suchlike). We want to know the exact parameters in the theory, so the theorists have some hard numbers to much on to make better overarching theories. And, there's always the possibility that something entirely new will crop up in these studies.

(A note on that last: modern neutrino detectors were born out of eariler attempts to build proton decay experiments... but the neutrinos kept getting in the way! On the 'don't beat 'em, join 'em' approach, people started looking at the neutrinos themselves with more interest.)

--Nathaniel, prowling his favourite topic.

at SNO's website.

I have to say, I pity those students.

One of the most refreshing and enjoyable aspects of my university years was the opportunity to discuss what we were being taught with fellow students who actually wanted to learn. Anything less and it would have been mind-numbing highschool all over again.

The next supernova is not, of course, known; they are essentially unpredicatable events. The next 'close by' supernova (i.e. detectable with neutrino observatories like SNO ) is likely to be at 10 kilo-Parsecs.. the centre of the galaxy (where most stars in our galaxy are). That is, approximately 31 000 light years.

Time scales are varied, depending on who you ask, but numbers like 20-60 years are quite common. Note that these represent 'mean time to next event', not the real time or most likely time.

The thesis has been done for over a year. Since it was a M.Sc. thesis I used science journal style references (Smith et al., 1999) and an alphabetically-by-author listed literature cited section. Not a challenge, really. The worst thing about Word was its insistence on "autoformatting" my section headings, invariably the wrong way.

BTW, I don't know what print nazi school you were thinking of, but at mine nobody needed a "professional printing service" to produce a properly formatted thesis. That's why we have "desktop publishing", anybody with a computer more advanced than a Mac Classic can produce a thesis that's perfectly acceptable at Queen's. Good thing too, with tuition there, that's about all you can afford ;-)

1. Build it into the application. Numerical methods developers have been known to do this.
   Many people in the parallel discrete event simulation community do this, sometimes using
   compiler assisted tools.
   
2. Build it into a middleware layer --- this is the approach typically taken by many database management systems, in parallel discrete event simulation toolkits , and in distributed process migration toolkits such as Condor and BSP
   
3. Build it into the kernel --- this was done by keykos and the eros group. If the kernel has support for persistent objects and the application uses this support, process restart is well defined. I've seen limited forms of suspend and wakeup for mobile devices as well, but this requires an explicit suspend/restart rather than fast crash recovery like eros has.
   

Glad to see SC is making progress. Another one of my favorite SC spin offs is Quilt, a replacement for the dated make. Additionally, SCons is a similar program which won the SC build competition in August 2000. Although I personally haven't used Quilt nor SCons, they appear to be well-designed pieces of software. Hopefully Software Carpentry will act as a catalyst allowing the creative juices of progammers around the world to create the most well-designed software possible. So far, I'd say it succeeded.

Hi,

Neutrinos interact with matter only through the weak nuclear force (and probably the gravitational force; whether they have mass or not is still kind of open, although it seems increasingly more likely that they have a non-zero mass). You are correct that the neutrino reaction does not directly produce a gamma ray photon.

The collision of a neutrino with a chlorine atom changes one of the chlorine atom's neutrons into a proton (note: a weak nuclear reaction), thus transforming the Chlorine atom to an Argon atom (atomic numbers 17 and 18, respectively). The reaction also produces an electron (charge must be conserved).

The particular isotope of argon produced (Ar-37) is unstable to radioactive decay. In a few days it spontaneously reverts back to Chlorine-37, producing an anti-electron in the process:

Ar(37) -> Cl(37) + neutrino + e(+)

The anti-electron immediately finds its way to the nearest electron, and they annihilate, producing a pair of gamma rays, which lead to a cascade of optical photons, which are detected by the experiment.

Whew.

Note that Super-K (the Japanese experiment that was damaged recently) doesn't actually use this chlorine setup, it uses something similar using ultra-pure water as the reactant. Also, I believe the water-based detectors rely on the kinetic energy of the electron in the first reaction to produce cerenkov radiation, rather than a subsequent beta decay/annihilation of anti-electron.

Here are some links on neutrino detector experiments. Google has all these and more.

The Solar Neutrino Problem

Review of all experiments

Sudbury Neutrino Observatory uses deuterium (a/k/a heavy water)

Super-Kamiokande

AMANDA uses Antarctic Ice as the reactant.

I recommend the first link for a detailed overview of solar neutrinos.

enjoy,
Jason

Just what is the SuperK?

A detector for neutrinos. Have a look at their web page.

I attended a talk last night by one of the scientists from the Sudbury neutrino detector. One of their Big Issues at the moment is figuring out why all the best neutrino detectors only pick up a fraction of the neutrinos predicted by all the best theories on the innards of stars.

...laura

Here is the link to the site in Canada...

http://www.sno.phy.queensu.ca