## Saturday, November 26, 2005 ... //

### Holographic 300 GB disks

What is the capacity of optical disks? If they're DVDs, you can squeeze up to 4.7 GB of information on them. Imagine a very similar disk with 300 GB on it. Yes, it is more than the magnetic hard disks you have ever seen.

Amazingly enough, some readers found the opportunity to argue about the previous sentence to be more interesting than the new fascinating technology described below - very sad.

And it would read the information 10 times as fast as the DVDs. Impossible? No!

has developed a commercially acceptable version of the holographic disks. It could be sold as early as in 2006. The required physics was discovered by Dennis Gabor in the 1950s using the methods of anticipation plagiarism. More concretely, Gabor stole the insights about the holographic principle in quantum gravity from 't Hooft and Susskind and applied them in optics 40 years before 't Hooft and Susskind published it and 60 years before string theory was confirmed experimentally.

Unfortunately, 300 GB is still 50 orders of magnitude less than what the area should be able to store according to the holographic principle ;-), but it is progress nevertheless. See other articles via news.google.com or the company's web. If you're interested, you should certainly see the WMV video or another exciting QuickTime video.

PDF introductions:

Paradoxically, the holographic disks are the first ones in which not only the two-dimensional surface but also the three-dimensional bulk of the medium is used. One can record thousands of holograms on the same medium by changing the angles or frequencies. Many bits are read simultaneously. The hologram is written down by adjusting many bits in a semi-transparent two-dimensional "checkerboard" which is really called "spatial light modulator" or LSM (also known as the "linear sigma-model") and letting two parts of a split laser beam to interfere with each other to create a three-dimensional pattern within the optically sensitive plastic medium. The LSM does not differ much from some modern types of displays.

When you read the data, you only use the reference beam that deflects off the medium and reconstructs a similar checkerboard image in a "detector".

The disks are slightly thicker than the DVDs but have the same area. The optimists predict that these disks could eventually store up to 1,600 gigabytes of data that could be read as quickly as 15 megabytes per second. Of course, technology will only be pushed to the limits if the modest versions of the disk turn out to be reliable.

Although the idea of the holographic storage disks has been around since 1963, people could not find a good enough medium for 40 years. The two-chemistry "TapestryTM" disks have suddenly solved these problems. The lesson - one that even the string theorists should learn - is that even if you have a great idea deeply connected with an obviously important physical principle such as holography, it may take 40 years - years of listening to obnoxious Peterwoits - before the details are refined so that you may celebrate the final success. Fourty years? String theory was born in 1968. You can do the math.

Incidentally, the readers who think that this posting - about a fascinating technology that has become a reality - should ignite discussions about the capacity of conventional magnetic hard disks are considered to be retarded and uncultural intellectual equivalents of dogs by The Reference Frame. But feel free to write whatever you want.

Haf haf. (That was in the Czech dogs' language. Not sure how the American dogs translate it.)