A Tektronix oscilloscope that moved faster than light?

The science world is abuzz this week with an odd scientific discovery from Europe -- neutrinos that appear to travel faster than light.

That opens up all sorts of anomalous possibilities, like time machines, interstellar travel and the like. And it got onetime Oregonian (and Oregon Journal) science writer Jim Long thinking that he'd heard something similar out of Tektronix in the distant past.

It didn't ring a bell with me, nor (at first) with a couple Tek alums I queried.

But Oregonian environmental writer Scott Learn wouldn't let it rest. He dug around and came up with a 1986 research paper out of Princeton that hypothesizes "Radiation from a Superluminal Source" -- specifically, from a Tektronix 7104 oscilloscope.

So what's the deal? Was Tek bending time back in the Reagan era, using an oscilloscope instead of a DeLorean? ("Back to the Future" hit theaters in 1985.)

No, of course not. But we've come this far -- let's take this silly walk.

The paper by physicist Kirk T. McDonald hypothesizes that it might be possible to use an oscilloscope to generate radiation that might otherwise be associated with particles moving faster than light without actually pushing the electrons involved over the hump.

Here's the paper's abstract:

The sweep speed of an electron beam across the face of an oscilloscope can exceed the velocity of light, although of course the velocity of the electrons does not. Associated with this possibility there should be a kind of Cerenkov radiation, as if the oscilloscope trace were due to a charge moving with superluminal velocity.

Lost yet? I was. Fortunately, Tektronix alum John Addis worked on the 7104 and shared his thoughts:

There is nothing too mysterious about the spot moving faster than the speed of light. This is called "phase velocity" and does not come under the heading of something physically moving faster than the speed of light.

If you sweep a flashlight across the night sky, someplace far enough from the earth, the tip of that beam will describe a spot moving faster than the speed of light. No information is passed from one end of the sweep to the other. The only information, traveling at the speed of light, comes from the flashlight to the someplace distant.

That is what happens with the 7104 CRT "superluminal velocity". I doubt this has anything to do with Chrenkov radiation either, no matter what the paper argues. Chrenkov radiation is radiation (often visible) given off when a particle travels faster than the speed of light in that medium. The particle is still traveling slower than c (the scientific notation for the speed of light) but the speed of light in the medium (such as water) is less than c, so no laws of physics are broken.

I can see how the message got a little twisted that Tek had something to do with "superluminal velocity". We all knew about it when we were working on the 7104, but considered it interesting but trivial. What is astounding about the 7104 is that you can see with the naked eye a single event plotted out on the CRT which happens in a nanosecond or so. That is about 5,000 times "brighter" than you can see on any oscilloscope before the 7104. Only Tek made scopes that would do that.

Now the same information is obtained using digital techniques and displaying the result just like a TV screen would, at low speed.

Thanks for the memories.

-- Mike Rogoway; twitter: @rogoway; phone: 503-294-7699