Unfortunately for the poor crackpot - there are quite a few problems with his physics.
1) Photons _do_ interact. (Maxwells equations are linear - but theses are only an approximation of reality.) If you use relativistic quantum mechanics - you will find that there is a fourth order diagram where two photons can interact via the exchange of electron / positron pairs. This means that his parameter U is not zero as he claims.
2) Photons do have zero rest mass - however photons contain energy (E=hf) This means that they contribute to the Stress-Energy Tensor T_ab
Now G_ab = 8Pi T_ab Where G_ab describes the curvature of space-time. This means that if you have alot of photons - you can curve space. This means that his approximation of zero graviational mass for photons is also wrong.
3) For his machine to work - it needs to radiate photons. Now this costs energy. I don't think he has calculated the amount required;-). (Light sails accelerate extremely slowly - and this guy wants to make something accelerate at 9.8m/s^2) Oops.
There is one final hint that something is wrong. At the bottom of the page are the plans for a perpetual motion machine - always a tip off....
This result is interesting because previously this problem has been treated by using approximations. The many different "solutions" given by wildly differing methods did not agree - and the errors introduced by the approximations also were impossible to find.
Numerical methods are very good in that you know the degree of error. Increase the number of grid points, and the error will decrease... (but the computation time will increase accordingly.) This one fact means that the results produced are meaningful - they can be compared with experiment.
Now why are these scattering events interesting? Well there is a slightly more complicated collision where the incoming electron knocks out an electron - leaving the atom in an excited state. The excited atom then de-excites itself by emitting yet another electron. (Auger emission.) You can't do this with hydrogen (not enough electrons.) - However, the nobel gases work well...
This second type of collision is very interesting, in that the distribution of outgoing electrons is related to the Fourier transform of the wavefunctions of the electrons in the atom... You can "map" the distribution of an electron in an orbital with this technique. This in turn provides tests on the quantum theory...
This also happens in ionisation events that form Aurora.
It is "illegal" in very few countrys. The web is world wide - so they are just threatening everyone elsewhere with lawsuits to keep this under wraps. These are just threats though - in Austrailia for example, reverse enginering for interoperability is explicitly allowed - so any files there are "safe". This won't stop them trying of course. However cutting off heads of an exponentially growing hydra is a very boring (and expensive) task...
The problem with building things at the nanometer scale is putting them together. We can make individual wires, transistors, bearings, shafts etc. out of atoms, but we can't put them together...
You really can't get out some tweasers and squint a bit to make a machine that will fit inside a cells nucleus.
These biotech guys have one way of organising the construction process. It is much easier to use DNA to drag prefabricated components together than to use pure chemistry to build them on site. (You need selectivity to make sure this bit gets made or put here, and not there.)
Unfortunately, I don't think this will work. DNA is just too big for the parts they are making at the moment. (The parts are made chemically - so they can only be a few hundred atoms or so before the yield drops off.) The way around this is to make successively smaller machines that can build yet smaller machines, and so on. The problem is that I don't see anyone with the blueprints for a universal constructor.
"But what about dust and scratches from which we all suffer with the current CDs? "
CD's currently have error protection such that if 600 bits in a row are miss-read the corrected stream is still correct. (If I recall correctly.) This is why radial scratches on a CD do not harm the data. (They tell you to clean them by rubbing from the hub outwards with a soft cloth.) However, scratches going the other way destroy data.
By using higher order codes you can make the biggest corrected miss-read sequences longer. However, this drops the effective storage density. You could still have an external disc based on this technology - but most of the data on the disc will have to be there to remove the errors produced by dust on the surface...
Floppy discs originally had the same problem - but when they are put into self-cleaning jackets it went away.
These new discs will probably have to be protected inside some form of cartridge if they will be removable.
Data storage density is going up and up...
on
Penny-Sized CDs
·
· Score: 2
I wonder how many DVD's you would fit on these micro-mini-ultra-compact discs? The days of having every episode of every TV program ever made on a piece of silicon are close...
That is if they agree to some format with "copy protection"...
Slashdot Mirror
Unfortunately for the poor crackpot - there are quite a few problems with his physics.
;-). (Light sails accelerate extremely slowly - and this guy wants to make something accelerate at 9.8m/s^2) Oops.
1) Photons _do_ interact. (Maxwells equations are linear - but theses are only an approximation of reality.) If you use relativistic quantum mechanics - you will find that there is a fourth order diagram where two photons can interact via the exchange of electron / positron pairs. This means that his parameter U is not zero as he claims.
2) Photons do have zero rest mass - however photons contain energy (E=hf) This means that they contribute to the Stress-Energy Tensor T_ab
Now G_ab = 8Pi T_ab Where G_ab describes the curvature of space-time. This means that if you have alot of photons - you can curve space. This means that his approximation of zero graviational mass for photons is also wrong.
3) For his machine to work - it needs to radiate photons. Now this costs energy. I don't think he has calculated the amount required
There is one final hint that something is wrong. At the bottom of the page are the plans for a perpetual motion machine - always a tip off....
As Terry Pratchett says:
"Million to one chances happen nine times out of ten."
This result is interesting because previously this problem has been treated by using approximations. The many different "solutions" given by wildly differing methods did not agree - and the errors introduced by the approximations also were impossible to find.
Numerical methods are very good in that you know the degree of error. Increase the number of grid points, and the error will decrease... (but the computation time will increase accordingly.) This one fact means that the results produced are meaningful - they can be compared with experiment.
Now why are these scattering events interesting? Well there is a slightly more complicated collision where the incoming electron knocks out an electron - leaving the atom in an excited state. The excited atom then de-excites itself by emitting yet another electron. (Auger emission.) You can't do this with hydrogen (not enough electrons.) - However, the nobel gases work well...
This second type of collision is very interesting, in that the distribution of outgoing electrons is related to the Fourier transform of the wavefunctions of the electrons in the atom... You can "map" the distribution of an electron in an orbital with this technique. This in turn provides tests on the quantum theory...
This also happens in ionisation events that form Aurora.
It is "illegal" in very few countrys. The web is world wide - so they are just threatening everyone elsewhere with lawsuits to keep this under wraps. These are just threats though - in Austrailia for example, reverse enginering for interoperability is explicitly allowed - so any files there are "safe". This won't stop them trying of course. However cutting off heads of an exponentially growing hydra is a very boring (and expensive) task...
The problem with building things at the nanometer scale is putting them together. We can make individual wires, transistors, bearings, shafts etc. out of atoms, but we can't put them together...
You really can't get out some tweasers and squint a bit to make a machine that will fit inside a cells nucleus.
These biotech guys have one way of organising the construction process. It is much easier to use DNA to drag prefabricated components together than to use pure chemistry to build them on site. (You need selectivity to make sure this bit gets made or put here, and not there.)
Unfortunately, I don't think this will work. DNA is just too big for the parts they are making at the moment. (The parts are made chemically - so they can only be a few hundred atoms or so before the yield drops off.) The way around this is to make successively smaller machines that can build yet smaller machines, and so on. The problem is that I don't see anyone with the blueprints for a universal constructor.
"But what about dust and scratches from which we all suffer with the current CDs? "
CD's currently have error protection such that if 600 bits in a row are miss-read the corrected stream is still correct. (If I recall correctly.) This is why radial scratches on a CD do not harm the data. (They tell you to clean them by rubbing from the hub outwards with a soft cloth.) However, scratches going the other way destroy data.
By using higher order codes you can make the biggest corrected miss-read sequences longer. However, this drops the effective storage density. You could still have an external disc based on this technology - but most of the data on the disc will have to be there to remove the errors produced by dust on the surface...
Floppy discs originally had the same problem - but when they are put into self-cleaning jackets it went away.
These new discs will probably have to be protected inside some form of cartridge if they will be removable.
I wonder how many DVD's you would fit on these micro-mini-ultra-compact discs? The days of having every episode of every TV program ever made on a piece of silicon are close...
That is if they agree to some format with "copy protection"...