Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Storing data into crystals?

  1. May 9, 2007 #1
    First i want to say hello, since i am new here.

    ok, I dont know tons about physics, so the following is an idea that i have, and would like to know if it was possible.

    my idea is:
    Why not use a laser to write 0's and 1's inside a glass or stone crystal? we can already use such lasers to make a picture at a specific point inside the crystal; whether it be glass or stone.

    reading should be easy, just use another laser ( probably combination CD-ROM laser & specific point laser), to send the data back to the CPU.

    Transferring data through glass (fiber optic tubes) has proven to have near unlimited bandwidth plus huge speed difference from copper. Over in Russia, i have heard that they were able to shove 1Tb worth of data per second through a single thread of fiber over 500miles.

    Is this idea possible? please don't ridicule the idea.
    btw, i hope i am posting in the right forum.
     
  2. jcsd
  3. May 9, 2007 #2

    chroot

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

  4. May 9, 2007 #3
    wow, fast reply :D

    anyway, wow, didn't know that. finally, something to get off our dependency of magnetic disk storage (HDD). I first saw this in the TV series, Stargate SG-1 (which btw i love :D ). I was thinking of a way to make this a reality because with the increase in access time of super high density 1Tb HDD's, its becoming "stupid" (for lack of better word). I finally came up with a solution today and wanted to share it with the Physics world.
     
  5. May 9, 2007 #4
  6. May 9, 2007 #5
    woah :surprised nice... but gotta have a big pocket to buy that. but 80mb transfer rate is slow. the limiter is the computer. if today's computers had fiberoptic cables in them, the transfer rates would skyrocket.

    re stargate: its in on of the episode where Earth receives the Asguard technology (beam tech etc). Thor hands Carter a crystal that she uses to control the new Asguard computer interface. the crystal stores data on it as well.

    also, the crystal elec panels and crystal points to the central computer Hub. gotta look close but they resemble today's circuits, but set in crystals.

    Also, one episode where they travel to a world where SG1 finds a field of crystals which turn out to be containing superficial beings (still consisdered data) . Oneal gets trapped in one.
     
  7. May 9, 2007 #6

    chroot

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Just a note: this is a gross oversimplification. The overall speed of any computer system is dependent upon many, many design choices. The bandwidth of interconnects is not necessarily the limiting factor in many computer architectures. Often, latency is a bigger handicap than bandwidth.

    For example, look into the node-to-node interconnect fabrics used in very large single-system image computers, like CrayLink/NUMALink.

    http://en.wikipedia.org/wiki/CrayLink

    - Warren
     
  8. May 9, 2007 #7
    yup thats what i was implying.
    <my understanding > You can only pass so much info through copper wiring tho. its like PVC piping, you can only pump X amount of gallons through an X inch diameter. but with light, it travels much faster so it doesnt take as long to go through the pipe, allowing more stuff to flow through :D </ my understanding>
     
  9. May 9, 2007 #8

    chroot

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Sorry, but I can't even begin to tell you how wrong that understanding is. It's complete BS. I mean, complete, 100% fantasy.

    - Warren
     
  10. May 9, 2007 #9
    I remember now, asgard and the ancients used alot of crystal tech.

    Crystal are highly ordered arrays of atoms,that's why it makes sense to use them as storage devices. It's just a matter of altering the properties of the crystal lattice, 0's and 1's.

    There was actually an experiment, where you could record your voice on a crystal when applied electric field. The atoms would align themselves in a line to a sound wave. When the electric field was changed, the sound pattern would be released.
     
  11. May 9, 2007 #10
    really.... ok then i guess i am wrong then, or you dont understand what i am talking about as I have a hard time explaining things. however, you don't have to put in a mean way... :frown:
     
  12. May 9, 2007 #11

    chroot

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Sorry, I didn't intend to be mean, but I can understand why it seemed mean. We just have a problem on this site with new members trying to spread their (incorrect) personal theories about physics, so I'm a little sensitive. Let me explain why your understanding is wrong...

    It's true that you can only shove a limited number of electrons per second through a wire before it melts. It's also true that you can send an (essentially) unlimited number of photons through a fiber optic cable simultaneously.

    On the surface, this would appear to mean that fiber optic cables can carry an immensely larger "volume" of data per unit time.

    The problem with that conclusion is that it assumes that information occupies space, or that the quantity of information is somehow directly related to the number of electrons or the number of photons used in transmission. This is what's wrong with your understanding -- sending more information does not imply pushing more electrons through a wire, or more photons through a fiber optic cable.

    Consider a signal that's just a clean, pure sine wave of a specific frequency. If you pass this signal through a wire, the electrons just oscillate back and forth inside the wire; if we ignore thermal motion, the electrons don't actually move from one end of the wire to the other at all. Passing this same signal through a fiber optic cable just means sending light of one specific frequency.

    Now, consider sending two signals at once. You add another sine wave to your existing one, the new one of a different frequency. When you pass this signal through the wire, the net movement of the electrons is still zero. Their oscillations are now more complex, but they still do not move any more energetically. Passing the signal through the fiber optic cable might mean just passing two light beams through it at once (assuming it's multi-mode and all that), but there are other ways of accomplishing it, too.

    The bottom line is that you can stuff as many different sine waves of different frequencies as you want through a copper wire, as long as your sine waves are all of frequencies less than some tens of gigahertz. You can continue to stuff the sine waves in with frequencies that get closer and closer, ad infinitum. In that sense, the "information bandwidth" of a copper wire is infinite.

    The only problem is that your receiver has to become more and more sophisticated in order to distinguish all these sine waves of very very slightly different frequencies, and unfortunately it'll have to start looking at the signal for a longer and longer period of time to distinguish a sine wave of one frequency from one with a very close neighboring frequency. This effect works against you, so you'll have to make some trade-offs between how you use bandwidth and how you design your receiver. The conclusion of all this is that it's the practical concerns about designing a receiver that limit how much data you can practically send over a copper wire. You could theoretically send an infinite amout of information over a copper wire, but you could not build a receiver to capture it all.

    The exact same argument applies to signals sent over fiber optic media. In other words, the "theoretical information capacity" of fiber is also infinite, since nothing's stopping you from sending many many many trillions of different wavelengths through it at once. On the oither hand, you'll never be able to develop a receiver which can decipher the resulting signal.

    The speed of propagation, by the way, is not so much of a concern. Light travels at about one foot per nanosecond, and electric signals propagate through wires at about half that. It's true that the light signal propagates more quickly to its destination. However, if you're sending a continuous stream of data from one place to another -- say, from a broadcasting station to a bunch of different TVs -- it doesn't really matter if the data gets there a bit earlier, or a bit later. It still comes in the same quantity of data per second.

    - Warren
     
  13. May 9, 2007 #12
    Why do you think light travels so much faster than an electric current in a copper wire?
    -
    Edit: Question directed to skiesofbordom, not chroot.
     
    Last edited: May 9, 2007
  14. May 9, 2007 #13
    @ chroot: thank you for explaining. it made me understand the technicalities better.

    I realized that alot of people may post things they think to be true when they are not so i use the <my understanding> bracket to signify that it was mine, not an actual fact in case i am wrong.

    but anyway, correct me if i am wrong, aren't fiber optic receivers capable of sorting & interpreting the waves alot better than copper??

    @ Averagesupernova: hmmm to be honest, i dont know tons about light, in this case i just remember from textbooks that it DID in fact travel faster than electrons through copper wire.

    i am going back to college to learn more about physics, ultimately theoretical stuff. ( i hope ) . if not, architecture or computer programming.
     
  15. May 9, 2007 #14

    chroot

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Nope, receivers of all types are subject to the same limitations. The main reason people use fiber is NOT because its propagation speed is faster, but because it is a less dispersive medium, which means it preserves waveforms from one end to the other better than wires. Wires have non-linear frequency response, which means that high frequencies get attenuated more than low frequencies.

    If you suspend a wire in vacuum, a signal will propagate through it at the speed of light. If you encase the wire in a piece of fiberglass, like on a circuit board, you cut the signal propagation speed roughly in half.

    - Warren
     
  16. May 9, 2007 #15
    :bugeye: hmm... well i ment under normal un-vaccuum'ed environments.

    hmm then i am guessing it has something to do with the resistance in the wire?
     
  17. May 9, 2007 #16

    chroot

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    The signal propagation in a wire has nothing to do with the wire itself -- it has everything to do with the material surrounding the wire. Specifically, it has to do with the dieletric constant of that material. As a signal propagates down the wire, the magnetic field around the wire must change accordingly. The material around the wire determines how quickly that can happen, and thus how quickly the signal can propagate.

    You can build circuit boards out of different materials specifically to choose whatever propagation velocity you want.

    - Warren
     
  18. May 9, 2007 #17
    Chroot, I'm not sure what you said is correct (unless I misunderstood you, which I may have). The information bandwidth of a copper wire isn't infinite, theoretically or practically. If you're modulating a signal with some bandwidth B, you can only space your carrier frequencies B apart, lest you begin to mix your signals. Since the best, most expensive, coaxial cable can only transmit signals up to the 100 GHz range, if you wanted to have channels with a bandwidth of 1 GHz, you'd be able to have 100 channels, tops.
     
  19. May 9, 2007 #18

    chroot

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Consider a form of keying where you represent a bit of data by the presence or absence of a carrier. Theoretically, each carrier has zero channel width, and thus you can pack an infinite number of channels into any finite bandwidth. As I've said, this is neither physically realizable or useful, so it doesn't really matter.

    - Warren
     
  20. May 10, 2007 #19
    That would be a crazy modulation scheme. Well, then, I'm going to save the validity of my statement by claiming that the time-energy uncertainty principle of QM limits your linewidth to a finite value. :biggrin:
     
  21. May 12, 2007 #20
    chroot's right its not the resistance in the wire, its the capacitance and inductance, which is the root cause for a velocity factor of less than 1 and greater attenuation at higher frequencies.
     
    Last edited: May 12, 2007
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Storing data into crystals?
  1. Crystal Radio (Replies: 2)

Loading...