Discussion Forum—A Way with Words, a fun radio show and podcast about language

On the topic of "clockwise" and "counterclockwise" there's two comments I want to respond to ...

Ron Draney said: Over twenty years ago, I came up with two examples of common expressions that I figured would be obsolete in a hundred years (eighty more to go!). One was clockwise, because I figured all clocks would be digital by that time.  

I thought the same thing, when I bought my first digital watch in the 80s. There's been a few threads on this forum about whether "clockwise" and "counterclockwise" would ever truly lose their meanings. You can get a widget for your desktop or smart phone that replaces the default digital display with something that looks and acts like an analog clock. In fact, you can buy (internally) digital watches that show the old analog display of rotating hands, but in pixels. I haven't seen many of those pseudo-analog devices in use though. I believe the consensus in all those other threads was that, as long as there were large analog clocks on city halls, church towers, monuments, etc., people would continue to understand the meaning of "clockwise" and "counterclockwise". I can't imagine Big Ben ever being swapped out for a digital display.

deaconB asked: If you were communicating by text to an alien living in a remote galaxy. how would you define clockwise or counterclockwise?  Or, for that matter, right and left?

Now that is a truly fascinating question I've pondered on many occasions. I'm a huge supporter of the SETI project, and interested in an obscure field of research called "anti-cryptography" (communicating in a way that enhances deciphering by a foreign intelligence). Disclaimer: I do believe there is other intelligent life somewhere in our galaxy. I do not believe we have been visited by them. Nor are we likely to be. That's a debate for a different forum ... just wanted to let you know where I was coming from.

Any conversation we have with an extraterrestrial civilization will be via radio waves (or, equivalently, laser light). This would not be an ordinary "conversation" since a question would take 4 years to reach just the nearest star. If they replied immediately, their answer would take another 4 years to return. So whatever the content of the message, it needs to be recognizable, decipherable, and have carefully selected clues to build a basis of communication (more about that below).

The answer to the question deaconB asked is a resounding YES. This specific problem (CW vs. CCW and L vs. R), is very important for scientific communication. And it was solved for us by the laws of physics. Here's the stages through which SETI experts expect communication to unfold:

1. Any communication with an extraterrestrial intelligence will begin with mathematics, using ideas that can be sent and received as a string of bits. For example, the universal constant pi (circumference/diameter ratio of a circle). Any such string of bits would be instantly recognized by a technologically advanced civilization. I believe SETI currently filters signals they receive in every base from binary to base 1000 (citation needed).
2. Once we establish a common mathematical base, we move to "graphics". The Arecibo Project was the first such attempt. By sending a string that was 1679 bits long, we sent a clue to decoding it (anti-cryptography). 1679 is the product of two prime numbers (23 x 73). If you arrange the bits into a 23 x 73 grid, it forms a crude image that conveys visual information. Follow that link and you'll see what the "picture" looked like.
3. Once graphic communication has been established, we can move into realm of geometry. The laws of geometry have a huge overlap with the laws of physics. This is where the real vocabulary begins to build, and true communication can begin. Plus, we're already at the point where we can define CW vs. CCW and L vs. R.

There are two laws of physics that would be well-known to any civilization capable of sending and receiving signals. Both involve 3D effects that allow for unambiguous definitions of rotation and direction. And we've been working (successfully so far) under the assumption that the laws of physics are the same everywhere in the Universe, since Newton's Principia. We really only need one of the two laws, since once you have CW vs. CCW sorted out, you get L vs. R as a bonus. And vice versa. Here's those two laws, expressed in words rather than equations. You can find the equations online if you want, but words should be sufficient to get the idea across.

1. When an electron enters a magnetic field perpendicular to the lines of magnetic force it deflects in a direction determined by what's called the right hand rule. Good image of that here. The magnetic direction of "north" can be defined by a related effect, shown here.
2. The direction a gyroscope precesses when perturbed by a force perpendicular to its plane of rotation provides a similarly effective 3D frame of reference. Good image of that effect here.

Apologize for the long post, but two good questions were asked. The concept of establishing a means of communication with an extraterrestrial civilization has fascinated me for ages. I've no doubt we could get to stage 3 as described above. And in the process, communicate anthropo-specific concepts like CW CCW L R. But how far could we get beyond that? Could abstract concepts like God, evil, love, hate, beauty, or art even be approached? Much has been written on this question, and there's not much agreement. It's hard enough right here on Earth, where some languages have words for things other languages don't.

It just occurred to me that, since "they" would be in our own galaxy, even at stage 3, we could tell them that "clockwise" is the direction our galaxy rotates as seen from that nearest big galaxy over thataway (the one we call Andromeda).

deaconB said: If you have a sequence of digits that is XY characters long, one can arrange the digits on a rectangle, but do you have X rows of Y or Y rows of X?  And do you go left to right, or right to left, up to down or down to up.  Maybe you go down one ro, up the next?  And what if there is a sequence that repeats every XYZ digits?  That now defines a rectangular prism.

Another good question. I haven't seen the actual code they use at SETI, but I've read most of what they've published on this topic. I'm pretty sure that if they got to stage 2, and received a string of bits that was the product of two primes in length, the code would run through every permutation ... 23x73, 73x23, bits applied left to right, right to left, top to bottom, etc. Since any grid formed by the product of two primes would have a center square, the code would probably look at filling in the bits on spiral paths, both outwards and inwards. Not really that much work given the fast computers they use. And trust me, they don't want to miss anything, especially if they know it's there (having reached stage 2). Simple visual inspection will then see all but one of the renderings as "noise" and one that appears to contain visual information. And so it goes.

If the length of the string of bits was the product of 3 primes, a similar algorithm would look at all the rectangular prism permutations.

If the length was the product of 4 primes, that would be a real puzzle. But we assume "they" would also be using anti-cryptographic methods.

deaconB said: But what about check digits?  If you’re sending packets on the internet, you have an error-detecting code every packet, and if there’s an error, the nodes ask for a resend of that packet.  How do you determine whether that’s data or a checkdigit?  Your 16 digit Visa card number is actually a 15-digit with a 16th digit that will catch errors (including transposed digits).

Normal error checking doesn't really apply to SETI, because of the long exchange times. Once that signal is on its way, it's a done deal. The only way real "error checking" could be done is by sending multiple copies of the signal separated by an appropriate interval. They didn't do that at Arecibo ... that was a one shot burst. The other type of error checking you mentioned with credit cards can be done, using what's called a parity check in the final packet, but all that tells you is that an error exists, not where it is ... and it's not like you can request a resending.

I never meant to imply this was an easy quest, but SETI has some of the best scientists and programmers working for them. The possibility that worries me most, is that "they" could be much farther advanced and the signal would be sent via neutrinos or gravitational waves. Those are a bitch to detect, so we probably wouldn't even get to stage 1. We've only been using radio for about a century now. What are the odds that "they" are at the same primitive technological level as us? Not likely, say the experts. Still ... you can't win if you don't play.

deaconB said: It’s unreasonable to expect a radio signal to travel light-years without encountering static.

A perfectly valid point. Even in "empty" interstellar space the signal will encounter one particle for every cubic centimeter of volume. That's pretty empty, but over the light years that adds up to a significant number of encounters. Fortunately, the SETI experts have a workaround. Most of the signals sent and looked for are around 1420 MHz, in a narrow band protected by the International Telecommunications Union. So it's a "quiet" part of the spectrum here on Earth. But it's also "quiet" out in space, because 1420 MHz is the natural absorption and emission frequency of neutral hydrogen. And most of what's out there is hydrogen ... maybe 90%, with the rest being other simple molecules or ions or dust grains.

But for this hydrogen to absorb or emit, it needs to interact with something. If it's floating around out there nowhere near a star, it's pretty happy just staying neutral. So this turns out to be a relatively quiet part of the radio spectrum out in space, and is one of the places SETI looks for signals. Don't think of a SETI signal as a serial string of bits flowing along a conductor (or fiber optic cable). A SETI signal moving through space is a wavefront of trillions of radio photons spreading out into a larger (and weaker) front the farther it travels. Further, it's sent in an extremely narrow frequency range.

For data corruption to occur, say, a 0-bit getting flipped into a 1-bit, that bit (actually being carried by trillions of photons) would have to encounter a concentration of hydrogen atoms that, for whatever reason, were triggered to emit radio photons in the direction of the SETI signal. Astronomers consider that highly unlikely, even over a distance of many light years. About half the SETI operations online today still use this strategy.

The newer operations are moving in two diverging directions. One is to use "spread-spectrum" analysis that broadcasts or receives over a wide range of frequencies simultaneously (which allows the same kind of error checking as sending repeated signals at the same frequency). The other approach is based on the assumption that laser light in the 1420 Mhz range (which is microwaves, not visible light) would be more effective and hold its signal-to-noise ratio over greater distances. Of course, that requires a different type of transmitter and receiver.

Your quip about old TV shows just now being watched by ET brings up another interesting point. Unless "they" have receivers far superior to ours (and have decoded those signals, which were never tempered with anti-cryptology), "they" haven't yet seen "You Bet Your Life" with Groucho. The first signals from Earth that have a good chance of being detected are the ones from high power military radar, which started broadcasting in the 50s. These high-power bursts, repeated at regular intervals, would be evidence of an intelligent source. They contain no info beyond that, of course. It's a stage 1 contact.

But those signals are now about 65 light years from Earth and still going. To date, they have passed quite a few stars. Maybe around 1500, most of which, as we now know, have at least some planets. If "they" heard our radar, we may expect an answer in another 65 years (or less). Whether we hear it depends on how carefully we're listening.

Enjoying this discussion deaconB, but I fear we have diverged too far from the original question and lost other readers. Might be just you and me from here on.