Storage at the Speed of Light

Light moves at a speed of 299,792.458 kilometers a second (km/s) or 186,282.397 miles per second (MPS) [Gibbs 1997]. What if we could use the speed of light and the vasts distances of space as a storage medium? In this post I propose the basic premise to do just that, to have storage at the speed of light.

I think it’s best to start out with what this is and what it is not.

This isn’t going to make storage faster. In fact this is a linear sequential storage platform like tape storage, it has to be read in the order it is transmitted. There is no jumping ahead or back to pickup additional bits.

Storage only flows in one direction. Because we are dealing with massive distances storage can only flow in one direction at a time. This becomes important later on.

Now lets get into the details of this proposal. Einstein proposed that the speed of light is a constant in his famous and simple formula E=MC². In this formula C is a constant for the speed of light. The fastest moving thing known to humans.

Latency

On earth we experience latency, for example when we make a phone call half way around the world. This is caused by how fast we can transmit data from point A to point B. In my proposal latency is the storage medium. (Really it’s space.)

The simple formula for storage using the speed of light is distance (d) equals transmission time (t) multiplied by the speed of light (C) divided by 2. This of course assumes that the receiver (r) is capably of receiving data at the same speed as the transmitter, processing times at each end are 0, and as soon as data comes in it is sent back out in the opposite direction. This also doesn’t account for the addition of new data into the stream.

You might be asking why is this divided by 2. This is because you must have two satellites. The one nearest the earth that transmits and one d distance away from the first satellite that receives the signal and then sends it back to original satellite. If there wasn’t the second satellite it would just be broadcasted in to space never to be seen again. This is shown in the diagram below:

Example of Latency for Storage

Lets walk through an example of this. Let’s say I can transmit and receive at 3 Mb a Second and I need to transmit 180Mb of data (including protocols). How far apart do the two satellites need to be? First we need to see how long we will transmit for. That works out to 60 seconds (180/3). We know that light travels at 299,792.458 km/s. We multiply by 60 and find that the distance is ‭17,987,547.48‬ km or one light minute (the distance light travels in one minute in a vacuum). We then need to divide that by two since it will be 30 seconds out and 30 seconds back. So our satellites would at a minimum need to be ‭8,993,773.74‬ km apart.

In the above scenario it would take 1 minute to get the data back once it was put in the loop. Why? Because we are using latency (and space/time) as the storage medium. Space time becomes a tape cartridge and our satellites the read heads. We can only read the data when it comes around to a read head. In this case the one closest to Earth otherwise we have to wait for the data.

Adding Data to the Stream

Now what if we want to continue adding data to this stream, how is that done? We can accomplish this by moving the satellites further apart. So lets say we wanted to add an additional 180Mb of data to the stream in the above example. How far do we need to move the satellites apart? That’s fairly simple we just need to double their distance.

The how fast we double their distance is the hard part. Since our satellite can’t reach the speed of light the amount of data we can add to the stream is dependent on how fast the satellite is moving away from the other satellite. This can be figured out…

Let’s assume our satellite is moving at 692,017.92 km/h (430,000 MPH). Which will be the speed of the Parker Solar Probe later in its journey, “making it the fastest human-made object relative to the sun” (Parker 2018). That means, if our satellite were to travel at the same speed it would be going ‭11,533.632‬ km/m. Know that we can figure out how fast we can add data to our latency based storage.

To figure this out we will restate our original equation as the distance (11,533.632 km/m) times 2. We then divide by the speed of light (‭17,987,547.48‬ km/m). That will provide us with the time. Or about an additional 0.00128240 minutes (‭0.0769441 seconds) of transmission time per minute. This of course assume that the speed is constant.

Knowing that and that we can transmit at 3 Mbps, we could add about 0.230832331 Mb to the stream every second (‭0.0769441 * 3 = 0.230832331).

There are obviously faster long term storage methods than this. It’s still a very interesting way to use time and space to retain data for extended periods of time.

Limitations

There are obvious limitations to this that should be called out here.

• Hardware speed is not taken into account. Once a satellite revives data it must then process it and transmit it. This takes time and would increase the amount of time and reduce the amount of data stored in the time/space medium.
• Because of hardware speeds a loop could never be filled to maximum capacity and each half of the loop would need to maintain a given amount of “slack” space to accommodate the time it takes for hardware to re-transmit data.
• The formula’s don’t account for jitter. If a satellite were to speed up or slow down it would change the capacity of the system.
• Data would need to be encrypted. Because data would be transmitted in open space and would presumably be transmitted beyond just the two satellites, data encryption methods would need to be used.
• This does not take into account a reasonable transmission time. IE if it takes two weeks for data to make a round trip is that too long.
• This also doesn’t account for maximum transmission distances where the rest of the cosmic noise would drown out the data transmission. (Which would necessitate the need for a checksum system being added to the protocol.)
• It might be possible to gain higher amounts of data using multiple transmit frequencies, effectively increasing storage without increasing distances.

For the longest time most have seen latency as an issue or delay to be dealt with. It looks like it can be a very powerful storage method given enough space and time. If you think of the research being done to slow the speed of light (see Physicists Slow Speed of Light) it could be very interesting in the years to come.

This whole storage notion is just a random idea I had while volunteering at a Kansas 4-H SpaceTech Experience at the Kansas Cosmosphere. We had the youth doing an activity that mimicked satellites flying past Pluto. The youth could only go so fast relaying messages to the space craft. It reminded me of packets being pulled off a tape by a tape head. It made me think, why not use this as a storage medium.

I hope you enjoyed the read. May your servers keep running and your data center always be chilled.

Works Cited:

• Gibbs, Philip “How is the speed of light measured?” http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/measure_c.html; August, 5 2019; originally published 1997
• “Parker Solar Probe; The fastest, hottest mission under the sun” October, 31 2018; https://hub.jhu.edu/2018/10/31/parker-solar-probe-record-breaking-speed-distance/; August, 5 2019