Home |
Search |
Today's Posts |
#1
|
|||
|
|||
A question about speed and size.
Big Bill wrote:
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 A recurring thought has been keeping me awake of late and that is whether someone without your private key and without your passphrase can decrypt a message encrypted with your public key. Often, the argument revolves around applying greater and greater computer power to the task as key lengths become longer and longer. But it seems to me that there is an ultimate limit to the power of computers beyond which no technological breakthrough can reach. The imagination. Bear with me whilst I explain.If we reduce the size of a byte of memory to an atom of oxygen (which has eight electrons, one for each bit in the byte), it still takes a non-zero amount of time to flip the spin-state of each electron. This defines the ultimate speed of both a memory chip and a processor. Note that it takes the same amount of time to flip the spin-state of the one electron in an atom of hydrogen, so we don't gain anything by changing atoms. Use smaller particles. If we pack the atoms of our megacomputer as dense as possible without creating a neutron star, there is still a non-zero distance between atoms. It takes a finite amount of time for a signal to travel that distance. That defines the overall speed of the computer. Quantum mechanics. If we take all the atoms in the universe (oxygen, hydrogen, and all the others), that defines the ultimate size of a computer. We can allocate the atoms between memory and processor. Just remember, the number of atoms is finite; and we must reserve some for the nuclear power plant that will run this infernal device. Thus, the memory of our megacomputer is limited. Use two universes. I saw this concept in some very old technical periodical where the capacity and speed of an ultimate computer were quantified. The article was published just before the dawn of PCs, when minicomputers and microcomputers were being installed with faster capabilities at far less cost than mainframes. The point is that we can conceive of finite problems to be solved on a computer that exceed the capacity of any computer that could ever exist. Mine still won't make a cup of tea. As there is indeed a limit to computer power before conjecturing about a future super-computer cracking a PGP-encrypted message, we should consider whether that computer could fit into the universe. Perhaps we're inside that computer. Your thoughts on this would be very welcome. I have run out avenues to explore and worse still my GP will not increase my dose of Nembies. Re above: read something somewhere a bit back about time travel. If... one had enough resources, one could simulate all possibilities of past events. Throw away all the invalid scenarios and you're left with a snapshot of what happened in the past. Ergo time travel. There's a nasty caveat ;-) Should one subscribe to this view then it follows that of all possible simulations only one is the real one (running the simulations). It also follows each simulation must be accurate, is real to its inhabitants, & thus is a universe in its own right. One is forced to conclude that the chances of ourselves being the real "in charge" universe is bugger all. Sleep tight! g |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Hayter Double 3 mower - speed control unit question | United Kingdom | |||
Reactor size VS Tank Size? | Freshwater Aquaria Plants | |||
Self-Propelled mowers -- Single speed vs. Variable speed? | Lawns | |||
Roller Drums for tissue culture; a question of rotation speed | Orchids | |||
Roller Drums for tissue culture; a question of rotation speed | Orchids |