Hi,
I realize that when science started off we had no idea how much “everything’s relative”, but once it became known that there was a spectum in which you can pull light, heat, radiation or sound (not in that order) possible even speed, right? (CPU clock cycles?) … Why do we still use so many different units to measure such “similar” things? Couldn’t frequency designations be given to all of the above? Please try to limit your metric and English standard comparisons, I guess it makes sense that it would be hard to stop something many have already learned…I was just thinking eliminating so many different units would be about a newer simplicity to the way we measure so many phenonmena. Thanks in advance and God bless the wise ones:).
Mearurements are analytical tools. It makes sense to have many analytical tools.
Frequency alone is inadequate to describe the phenomena you mantion. There’s wavelength, amplitude, etc. For other real world phenomena, there are other measurements. Sometimes the simple act of attempting to measure things in non-customary measurements shows unexpected correlations between things, and leads to new or deeper understanding.
Speed is a thing? Far as I know, velocity is another analytical measurement. How did it get on the list?
It’s not as simple as elimnating units. Units are based on scale for the most part. We can standardize scales by using unitary systems. There are two basic systems that are in use today scientifically. One is SI the other is cgs. cgs is used mostly in astronomy and electrodynamics (where Gaussian units are handily normalized) but just about everyone else uses SI. The standardization is such that if you work solely within the system you there is no conversion back and forth required. You can just do your math and be confident your units will come out right in the wash as long as everything you input is starting out in the proper units.
Your bit about “frequency” is a tad misleading. Frequency can be measured any number of ways… it’s generally an oscillating function that has any number of “indicators” per “standard”. Most commonly, we use frequency to mean “complete wave” per “unit time”, but also common is angular frequency (complete cycle per unit time) or frequency in k-space (which is itself frequency!). Physical phenomena may have many repetitions in them, but that doesn’t mean that everything looks nice when we reduce it to its most basic fundamental parts. Sometimes things are easier to work with in a different unitary system simply because of the variables on which the system is dependent.
So to some extent, to ask us to limit our metric and English standard comparisons is to ask us to not answer your question. Today, people use the units that are generally most convenient for ease of communication and understanding. It may be completely arbitrary, but it serves a purpose. It might be nicer some for some areas of science if a meter were defined as how far light goes in a second, but then to measure the height of a human being would be in eight orders of magnitude smaller in those units, thus making it awkward to deal on that scale. In general, the systems we have right now are rigorously tested and well-measured by such folks as the NIST. This is why we stay with what we’ve got.
No, no, no, JS Princeton! Frequency dependent!
Photons can, at the most basic level, be described by a single number. It tells you what type of photon it is; for visible light, it tells you the color. The energy, wavelength, and frequency are all different ways of giving this one number. I always thought it was interesting that which one we use depends on the type of photon. For low-energy photons, like radio waves, we use frequency. For medium-energy, like visible light, we use wavelength. And for high-energy photons, like gamma rays, we use energy.
Remember that frequency is a scalar, and as yojimboguy points out is just one possible measurement. Right away this tells you that it is useless for vector quantities such as velocity, but it’s also not so useful for some of the things you mention:
Light, heat (IR radiation), and (gamma) radiation may all have frequencies, but that’s just the tip of the iceberg. The frequency is sufficient to tell you the energy in each photon, but it’s not sufficient to tell you how many photons there are. But, once we do know how many photons are coming from some source, is that good enough?
What do we want to know about light? How bright it is, what color it is, perhaps what it’s polarization is so that we can see it in our polarized sunglasses. Brightness may be useful to talk about in terms of something we’re familiar with, so there are units such as “candlepower” or “lumens”. Color is described by the frequency. Polarization can be given as a unit vector, or described as a time-varying angle for circular polarization.
What about heat? Well, are we talking only about infrared? If so, the frequency may not be all that important if we want to know how warm our toes are going to get by the fire, but may be very important if we want to know whether we can detect the signal from our remote control at the TV. Here again we may want to compare the strength of the signal to something we are familiar with, which could be a power rating (we may have 1000 Watt heaters in our bedrooms…)
But what if we aren’t talking about infrared radiation? Conducted heat doesn’t have the same frequency that infrared radiation does. The frequency of heat conducted in a metal is not a particularly useful thing to talk about - and what would we be talking about anyway? The frequency of vibrations in the lattice? Here the interesting aspects are conductivity of heat (a measure of the possible power conducted through the medium) and perhaps temperature, a measure of kinetic energy in the particles of some substance.
Sound is conducted in a different way than light is, so equivalent frequencies of sound and light are completely unrelated phenomena (without going into fun stuff like sonoluminescence.) If we didn’t specify that the things are different, we’d get confused.
I guess what I’m trying to say is that deciding to use “frequency” to measure as many things as possible regardless of utility is a bit like using color to describe all plants. Why not? All plants have a color. The problem is that you now can’t tell a red rose from a red geranium, or a green fir from a green elm or juniper. You can’t describe the smell of freshly mown hay, or of a rose. Think about how much we can’t describe with color.
Think about how much we can’t describe with words even =)… no this stuff is great. So doug, are you saying it’s possible to block and IR remote with a cranked up heater? or did I read that wrong. Thanks everyone, please keep it coming. Makes me regret never taking physics 
btw, your color analogy was quite effective thanks and Archernar, that’s pretty cool too. Thanks again. The SI units sound a bit more efficient than I had imagined, perhaps it’s how Einstein was such a great theorist and yet failed math. I’ve seen it many times were someone didn’t really know what they were doing and yet succeeded brilliantly be-cause of it. In receiving a formal education it closes some avenues of approach in your mind. Maybe there’s still hope me yet:)