Tom Lee wonders about a question that Ed has pondered in the past: how much bandwidth does one human being need?
I’m suspicious of estimates of exploding per capita bandwidth consumption. Yes, our bandwidth needs will continue to increase. But the human nervous system has its own bandwidth limits, too. Maybe there’ll be one more video resolution revolution — HDTV2, let’s say (pending the invention of a more confusing acronym). But to go beyond that will require video walls — they look cool in Total Recall, but why would you pay for something larger than your field of view? — or three-dimensional holo-whatnots. I’m sure the latter will be popularized eventually, but I’ll probably be pretty old and confused by then.
The human fovea has a finite number of neurons, and we’re already pretty good at keeping them busy. Personally, I think that household bandwidth use is likely to level off sometime in the next decade or two — there’s only so much data that a human body can use. Our bandwidth expenses as a percentage of income will then start to fall, both because the growth in demand has slowed and because income continues to rise, but also because the resource itself will continue to get cheaper as technology improves.
When thinking about this question, I think it’s important to remember that engineering is all about trade-offs. It’s often possible to substitute one kind of computing resource for another. For example, compression replaces bandwidth or storage with increased computation. Similarly, caching substitutes storage for bandwidth. We recently had a talk by Vivek Pai, a researcher here at Princeton who has been using aggressive caching algorithms to improve the quality of Internet access in parts of Africa where bandwidth is scarce.
So even if we reach the point where our broadband connections are fat enough to bring in as much information as the human nervous system can process, that doesn’t mean that more bandwidth wouldn’t continue to be valuable. Higher bandwidth means more flexibility in the design of online applications. In some cases, it might make more sense to bring raw data into the home and do calculations locally. In other cases, it might make more sense to pre-render data on a server farm and bring the finished image into the home.
One key issue is latency. People with cable or satellite TV service are used to near-instantaneous, flawless video content, which is difficult to stream reliably over a packet-switched network. So the television of the future is likely to be a peer-to-peer client that downloads anything it thinks its owner might want to see and caches it for later viewing. This isn’t strictly necessary, but it would improve the user experience. Likewise, there may be circumstances where users want to quickly load up their portable devices with several gigabytes of data for later offline viewing.
Finally, and probably most importantly, higher bandwidth allows us to economize on the time of the engineers building online applications. One of the consistent trends in the computer industry has been towards greater abstraction. There was a time when everyone wrote software in machine language. Now, a lot of software is written in high-level languages like Java, Perl, or Python that run slower but make life a lot easier for programmers. A decade ago, people trying to build rich web applications had to waste a lot of time optimizing their web applications to achieve acceptable performance on the slow hardware of the day. Today, computers are fast enough that developers can use high-level frameworks that are much more powerful but consume a lot more resources. Developers spend more time adding new features and less time trying to squeeze better performance out of the features they already have. Which means users get more and better applications.
The same principle is likely to apply to increased bandwidth, even beyond the point where we all have enough bandwidth to stream high-def video. Right now, web developers need to pay a fair amount of attention to whether data is stored on the client or the server and how to efficiently transmit it from one place to another. A world of abundant bandwidth will allow developers to do whatever makes the most sense computationally without worrying about the bandwidth constraints. Of course, I don’t know exactly what those frameworks will look like or what applications they will enable, but I don’t think it’s too much of a stretch to think that we’ll be able to continue finding uses for higher bandwidth for a long time.
