Products I Would Like To See

From time to time, I think of a product that I wish I could buy. The purpose of this page is to describe such products, in the hope that someone will either point out to me that they actually exist and where they can be found, or will start producing them. The only property right I claim for the ideas is the right to credit for having created them.

Programmable Tub

Redesigning Bathtub Plumbing

Exercise Video Game

Variable Stained Glass Window

Finding Books and Girlfriends

The Programmable, Thermostatic Tub

Those of us who like to soak in a bathtub face two serious problems:

1. Because of the way human temperature sensing works, a tub that will be hot enough once you are in it is uncomfortably hot to get into.

2. Bathtubs cool off over time. With conventional tub technology, keeping the water at a constant temperature requires you to continually drain off warm water in order to replace it with hot water. This is a nuisance--and an inefficient use of energy.

The solution is obvious. Make a bathtub that includes a programmable thermostatic heater. Set the heater with two temperatures--T1, the temperature that is comfortable to get into, and T2, the temperature that is comfortable to soak in. When the temperature reaches T1, a light goes on, telling you the bath is ready to get into. After you get in and press a button, the heater gradually raises the temperature to T2.

While some hot tubs have thermostatic heaters, I know of none that is programmable in this way, and none suitable for an ordinary bathtub.

And while we are on the subject of bathtubs ...

Getting Bathtub Plumbing Right

The standard bathtub design puts the controls, the faucet, the sprayer if there is one, and the drains at one end. In practice, that becomes the foot end. That means that if you want to add additional water once you are in the bath, you have to manipulate the controls with your feet--possible but a bit clumsy. And it puts the sprayer out of your reach unless you sit up in the bath.

A less common design groups everything in the middle of one side. That puts the controls and the sprayer within reach. But it means that if you want to add hot water in order to warm up the bath, you have to sit up--otherwise the hot water is coming in on top of you.

Both of these designs are fine for people who fill up the tub, get in, and add no more water until they get out. But they work badly for those who get in while the tub is filling and then adjust the temperature, or for bathers who like to soak in hot water, bringing the temperature back up from time to time by adding more. The obvious solution is to separate the faucet from the controls. Put the faucet at one end, the controls and sprayer on the side towards the other end. Now the hot water comes in at the foot end but controls and sprayer are within reach.

There is another problem that we can solve at the same time. With conventional designs, the water inlet is at the same end as the drain. So if the tub is full and you add more hot water to warm it out, most of the hot water goes right out again through the overflow drain. You can reduce the problem by first letting enough water out to lower the level below the overflow drain and then adding hot water, but that is a good deal of trouble, and you are still letting water out from the hotter end of the tub. The obvious solution is to move the drains to the opposite end of the tub from the faucet, perhaps putting the overflow drain at the side to reduce the chance that you will block it by leaning against it and flood the bathroom before you notice the problem--not unlikely for those of us who read in the bath.

All of these changes result in slightly increasing the amount of plumbing required for a bathtub. Presumably the standard designs are intended to keep that as simple as possible. But the additional cost should be small and the additional convenience, at least for those of us who like long baths, considerable.


The Exercise Video Game

The great advantage of sports over exercise machines is that you are too busy and excited trying to hit the ball, or throw your opponent over your shoulder, or parry a lunge, to notice that your muscles are complaining. A second advantage is that sports are less boring--although that can in part be dealt with by using your stepper or exercise cycle while reading a book or purusing the net.

The solution is to cross the exercise machine with the video game. Build something along the general lines of a fancy nautilus machine, where the moving parts provide the inputs to a video game. Think of it as a set of giant joysticks.

Imagine, for example, that the video game puts you in the role of an anti-aircraft gunner in the navy in WWII. Pushing your legs raises and lowers the point of aim of the gun, pulling with your hands swivels the gun right or left. The motions are the motions of an exercise machine--but while you are making them, you are too busy and excited trying to nail that Zero to notice how tired your muscles are getting.

The Mark II version of the game takes advantage of feedback to tune your exercise session to your precise needs. The computer judges how tired each group of muscles is by how hard you are pulling, how fast you are reacting. The objective is to get every muscle to the same point of exhaustion. If the computer concludes that your left arm has almost reached that point, it starts sending in almost all of the attacking planes on the right, forcing you to do most of the work with your right arm.

There exist rowing machines with a video screen simulating a race, and exercise cycles with a screen providing scenary. So far as I know, there is no exercise machine that is combined with a video game good enough so that anyone would play it for fun. But there should be.

[Since I wrote the above several correspondents have pointed out to me the existence of dancing games, originally from Japan, in which the player must move his feet from one area to another on instructions from the game.]

The Variable Stained Glass Window

an application of polarized light


There are materials in which right handed and left handed polarized light move at different velocities; one result is that if plane polarized light is passed through such a material, the plane of polarization is rotated, with the amount of rotation depending on the thickness of the material and the frequency of the light. One such material is, or at least used to be (I haven't played with polarizing filters for a long time), scotch tape.

If you put a sheet of such a material between two crossed polarizing filters, the result is striking. Wavelengths that are rotated by about 90° or about 270° pass through the second filter. Wavelengths rotated by about 0° or 280° do not. Different wavelengths correspond to different colors, so that material, viewed between the filters, is brilliantly colored. If you take a strip of scotch tape and fold it over itself, so that different parts have different numbers of layers hence different thicknesses, you get a pattern of colors.

This effect could be used artistically. Imagine a circular window which consists of three layers--an art work in scotch tape or something similar sandwiched between two layers of polarizing filters, at least one of which is free to be rotated. Arrange it with the filters crossed and the background to the work of art--the parts where there is nothing between them--are black. Arrange it with the filters parallel and the background is transparent. Colors vary as you vary the relative orientation of the filters.

Finding Books and Girlfriends


When I go into a bookstore, I look for books by a few authors I know I like. In a large bookstore, there are probably many more books that I would like, by authors I do not know. The problem is how to find them. A similar problem exists on the dating/sex/marriage market, where participants are trying to find mutually attractive partners--with long search times and a lot of frustration.

Imagine a book service that works as follows. Customers fill out a questionaire on what books they have liked or disliked. The service recommends additional books. Customers report on how they like them.

The service is based on the mathematics developed for multidimensional voting theory (I heard about this twenty years or so ago, and have no idea how it has gone since). Each voter has an ideal point in a multidimensional space of political preferences, as does each candidate. The voter votes for the candidate who comes closest to his ideal. The function of the mathematics is to start with the results of voting (who each voter voted for in each election) and reconstruct the space, presumably with a minimal number of dimensions.

Our candidates are books. Our voters are readers. When I report on what books I did or did not like, that provides two sorts of information. It locates my preferences more precisely in the space representing characteristics of books (given that you already have some information about where the books are located) and it locates each book more precisely, given that you already have some information about where I am located. As the picture of the space becomes more and more accurate with information from many readers, the recommendations--which consist of a list of the books whose estimated location is closest to my estimated location--become more and more likely to be books I will like.

A similar approach could be used for a computer dating service. In both cases, the essential idea is to start, not with a theory about what books or women I am likely to like, but with information about what books people like me (as judged by their taste in books) have liked. The picture of the space represents information on what books are similar to each other and what readers are similar to each other--or, in the dating case, what women are similar to each other (judged by their being liked or disliked by similar men) and what men are similar to each other (judged by the women they like or dislike).

In the dating case, since you have much larger numbers and much less information for each (a woman is dated by only a few men, a book read by a very large number of readers), you may have to use some other soource of information, say answers to a questionaire, to help identify similarities among men or among women. But here again, rather than starting with a theory about what questions matter, you should let the results tell you what questions matter. If there is no correlation between how two men answer a particular question and which women they like, that question doesn't matter.

I should add that I am told that something similar to what I have described is used online for music, but I have no experience with it. And it looks as though may now be employing something along the same lines for recommending books.

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