Domain: polytechnique.fr
Stories and comments across the archive that link to polytechnique.fr.
Comments · 7
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Run Community Projects
BOINC, Tor, Freenet and/or I2P are good examples of things you can put your extra resources to some use. Here are the BOINC projects I would run if I had 100's of system's at my disposal.
Artificial Intelligence System, NanoHive@Home, Predictor@Home, Project TANPAKU, Spinhenge@Home, The Lattice Project, World Community Grid, SIMAP, Malaria Control, Proteins@Home and Rosetta@Home. -
If students are plagarizing solutions...
...then it's a sign that you're not teaching an obscure enough programming language. Using C++ is like asking the students to cheat. You want to require all answers in Unicon, or Lambda Prolog, or (worst of all) POPLOG-11.
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Speed of Gravitational attraction ?
Last I heard there was some question as to the speed of gravitational attraction. IE if the effect of gravity is only as fast as that of light then the earth is being acted on by the gravity from the point the sun was at 8 minutes ago or some such while the sun is similarly being affected by the earths poistion from 8 minutes ago.
As these mass points get further and further apart this would have a huge effect on the results. Unless of course Gravity is instentaneous across any distance opening the door to some interesting possibilities. Namely the ability to communicate across large distances without delay. Perhaps even FTL travel.
While I find this excercise interesting I also find it a tad ridiculose. So many simplifications have to be made to even attempt it and the whole thing is based on some assumptions that are not necesarrily cold hard fact... such as the mass of the universe. Theory says one thing, observation says another. Dark matter was invented to close the gap. Don't get me wrong, there are a lot of smart people that have come up with an awful lot of observation which seems to confirm its existence, but it could be that our point of veiw is insufficient. After all by all observations the Ptolemaic model of the movement of the heavens was accurate and it had all sorts of added rules for handling what was observed.
Also there is the issue of the N body problem where N is greater than 2. Did you know we cannot accurately model our solar system just using keplers laws ? We have to create stabilising factors in the system to keep the planets paths from becoming unstable in their orbits. And yet here they are attempting to simulate an N body problem where N = 10 billion.
http://www.lactamme.polytechnique.fr/Mosaic/images /NCOR.11.16.D/display.html
That link shows what happens with a pure Keplerian system of equations for 9 bodies.
Thus introducing such things as mass simplification for objects farther away ( creating groupings etc ) and the tree approach for close objects all creates an introduction of error into the equation. Further more they have to use some means of stabilizing the equations similar to solar system models which is a value based on observation but with no understanding for what really controls it ( if they don't do this then the system of equations can't model our own solar system much less 10 billion mass points expanding since 380k years after the big bang ). This is all chance for more error to creep into the equation. Then with all of this they run a simulation for a simplified mass points using simplified interactions with an unkown stabilizing force over the course of billions of years and then expect people to believe that what they wind up with has any significant correlation to reality.
Do not be decieved by impressive things like 4 teraflops and 20 terabytes of information. To me this seems an interesting intellectual excercise, but the chances of the results being meaningful are pretty slim. -
Re:"hazards and risks are poorly understood"C-60 may be a large molecule but it's still small on the quantum scale, and hence has atomic-like states.
But don't just take my word for it. Why don't you check out this java applet . It shows the time-dependent Hamiltonian, diagonalizes it for you, and then shows what the energy eigenstate wavefunctions for the C-60 molecule look like.
Hint, at low energies (large wavelengths) they look just like the spherical harmonics. In other words there is no sense of the 'structure' of the C-60 molecule. At the larger energies, though, the wavefunctions and energy levels deviate from the spherical harmonics as they can now discern the hexagon/pentagon planes.
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Re:Municipal utilities are a double-edged sword
The first hurdle was trying to acquire the plastic box to put the meter in. We went to the Manx Electricity Authority shop and asked for one. We were told to fill in a confetti-like shower of forms, and we'd have to wait a couple of weeks for it to show up. The guy behind the desk wouldn't budge. He had them in stock, and available, but no, he couldn't give us one. He terminated the argument by announcing, "Well, we ARE the government, you know".
That's because you are in England. England, you know, is populated by english people, and english people have that collective neurosis about the State being bad (this comes directly from the Magna Carta). It's a vicious circle: people believe that the State is bad, so no one wants to be associated with the State, so smart people don't go work for the State, and the State does stupid things, which reinforces the perception.By contrast, look at France where people TRUST the State. Working for the State is not demeaned, and people see it as an honour, and there are those prestigious Grandes Écoles (great schools) who turn-out nothing but extremely competent bureaucrats (those schools skim the cream of the crop of each schools in France - they accept only the best of the best students). The result is extremely efficient and well-run public corporations and utilities, say like the SNCF which operates the largest network of the fastests trains in the known universe.
Instead of whining against filling forms, why don't you do something positive like trying to fix those problems by, say, bringing more smartness to their process???
As long as the anglo-saxons will have that shit-for-brains attitude against the State, you will get the shitty public service you rightfully deserve.
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avoiding runtime checks
Static analysis methods may remove as much as 90% of runtime checks.
For instance, such techniques may, on reading code such as:
for(int i=0; ia.length; i++)
{
x = a[i]; ...
}
derive the fact that the check on a[i] is unnecessary because 0=ia.length. -
Re:Change or Delete the Data?
As long as no one tries to decree the number of pi to be 3.2 again...