Faster Than The Wind

I was wrong. A year ago, my future son-in-law asked me if a sailboat could travel faster than the wind. I said no. If the sailboat were travelling faster than the wind, then, to a person on the boat, the wind would seem to be coming from the opposite direction. This applies to downwind sailing, not to tacking against the wind. My mistake was going with my intuition, not my analysis.

I have studied many websites explaining how a sailboat can go (at an upwind angle) faster than the wind. Most explanations are flawed. Many quote Bernoulli’s principle, which isn’t an explanation. In the same way, physicists have stopped using Bernoulli’s principle to explain why planes can fly. (Otherwise, how could they fly upside down?)

Some websites contain text or comments from readers linking the claim that a wind-propelled craft, on land or water, can travel faster than the wind to a claim of perpetual motion. This, of course, is faulty thinking. Such a vehicle is getting its energy from the wind, and the wind is losing energy to the craft. No wind, no motion. Nothing magic about that.

But, for those still worried about what pushes a boat faster than the wind, here’s a simple explanation. First, what pushes a tacking sailboat forward against the wind? The answer is, the water. The wind pushes the sail, which is attached to the boat. The sail pushes the boat, which includes the keel. The keel pushes the water back (at a slight angle) and the water pushes the boat forward [Newton's 3rd, action and reaction.] Remove the keel (e.g.. raise the centerboard on a tiny sailboat) and the wind shoves the boat back, no matter which direction the boat is facing.

The faster a tacking sailboat travels, the greater the force of the wind on the sail, the greater the force of the keel on the water, the greater the forward force of the water on the boat. The limiting factor is not the speed of the wind but the friction of the water on the hull.

Going downwind faster than the wind (DWFTTW) is a little more anti-intuitive. A great blog entry with videos that demonstrates that an object can move faster than the object (and wind is millions of “objects”, air molecules) that propels it is http://dwfttw.blogspot.com/.

Standard Accepted Knowledge

In my last article I commented on the differences in positions held by scientists and non-scientists on whether Earth had been visited in the past by intelligent extraterrestrials. I use the term scientists widely, not referring to an occupation but to a state of mind.

No matter what your occupation, I call you a scientist if you look for answers by studying the evidence; if you test to see if proposed explanations work; and if you assume that there are reasonable, physical explanations first, before resorting to magic or far-out justifications for an extraordinary claim.

I made a statement that there is near universal agreement among scientists on the big issues. Here is a list of what I consider those issues to be.

Earth is a speck in the cosmos. There are likely to be many small, rocky planets orbiting stars, some of which will be similar to our sun. There are so many stars, there are bound to me many Earth-like planets at suitable distances from their sun that conditions were similar to those on early Earth.

Earth is old and changing. Continents drift around and collide. Mountains rise. Rivers cut canyons. Lakes and oceans fill up with debris that eventually becomes sedimentary rock. As you dig down through layers you reach older and older rock.

Life processes follow the laws of chemistry and physics. There is no process that requires “magic”. We don’t know all the processes, but are confident that they are “knowable”. (Consider the opposite. If, for example, some magical process causes the heart to beat, then we might as well stop trying to understand how the heart works!)

Life evolves. Little changes in short periods add up to bigger changes over long periods.

The laws of mathematics and physics apply everywhere. The formula for a circle and value of pi is the same on Mars. Magicians don’t do true magic: they are still constrained by the laws of physics. (While watching a magic show, everytime you ask yourself, “How did he do that?” you are applying this concept. You feel that there was a physical explanation, a “trick”. You didn’t see true magic.)

Matter is particulate. Substances are made of atoms that join to become molecules. (Atoms themselves are made of particles.)

The properties an object possesses depend on the observer. (This claim, for which there is much evidence, arises from relativity and quantum physics. Relativity deals with the big concepts of time, space, gravity, matter and energy; quantum physics with the behaviour of matter and energy at the tiniest level.

I might as well mention the fringe items, too.

There are no ghosts, werewolves, vampires, living dead, mammoth spiders, King Kongs, Spidermen, invisible people, extraterrestrial aliens living amongst us.

Astrology is false.

There is no such thing as psychic ability. You can’t move objects by though alone. No one can actually read minds, see the future (rather than predict likelihoods), perceive present, past, or future events by other than the five senses.

Men HAVE landed on the moon (i.e. the landing in 1969 was not a hoax.)
Humans and dinosaurs did not inhabit the Earth at the same time.

I expect many to disagree with me on many of this last list. In particular, countless people will cite amazing occurrences, coincidences, anecdotes, and “facts”. I will leave it as this: I have seen no repeatable, non-controversial evidence that convinces me that, for example, ESP exists. A million dollar prize is available for ANY purported psychic who can demonstrate ANY psychic ability. No one has yet been able to do it.

As much as we, scientists included, might wish for exceptional abilities, extraordinary creatures, and assistance from the stars, there is just no good evidence for any of it.

ESP

I had a discussion recently with members of my writer’s club. A small group of us meet regularly to exchange critiques of our developing novels. Two involved forms of ESP. In one, a character had the ability to picture previous inhabitants of a house and, specifically, “feel” terrifying experiences that happened to others. Another novel featured a scene in which a character was awakened in the night at a crucial time via a “signal” from her distant mother.

I’m a physics teacher and sceptical of the these phenomena. No, I’ll be honest, I’m not just sceptical, I don’t believe ESP exists. I’m careful not to let this disbelief affect my critiques of the novels. After all, my novel-in-progress uses parallel universes, a concept no less dubius.

I made the mistake, at the end of the evening, of mentioning my scepticism. Jim, one of the authors, was incredulous. “You don’t believe in ESP?” he remarked.
Me: No. There’s no good evidence that ESP exists.
Jim: You don’t think people can read minds?”
Me: Of course not. Nobody has been able to demonstrate that ability when examined carefully.
Jim: How about Edgar Cayce?
Me: Are you kidding? Magicians can do that stuff.
By this time Jim was laughing. At first I thought he was just having fun. But he was laughing with disbelief that I could be so mistaken.
Jim: How about astral projection?
Me: For heaven’s sake. There’s no evidence for that.
Jim: [laughing harder] Uri Geller bending spoons?
Me: URI GELLER!!! He couldn’t do it on Johnny Carson. Magicians can bend spoons. They aren’t using any special powers.
Jim: Astrology?
Me: Jim, astrology and horoscopes are demonstrably false.
Jim: [laughing uproariously at my ignorance] Alien abductions?
Me: No way. There’s no evidence for that.
Jim: Have you read about Betty and Barney Hill.
Me: I’ve read about them, and am satisfied that alien abduction is not the explanation for Barney’s drawing.
Jim: Well, they’re my aunt and uncle. They believe it.

At this point, the teacher of our little group spoke up passionately.

Lynda: What about when a little girl at home sees her Dad in the doorway waving goodbye when he was actually in the hospital, and her Mom next to her in bed awakens and says “You just saw your Dad, didn’t you?” and the Mom telephones the hospital to find out that he just died?

I wanted to respond with some more old saws (like “when my grandmother died, her picture fell off the wall”) but bit my tongue, for Lynda was talking from personal experience.

Me: I accept that you experienced what you say, but my explanation might be different from yours.

Suffice it to say that I took quite a roasting for expressing strong doubts about ESP and its kin. There is not much you can say when honest, intelligent people give testimonials. When I related this story to my friend Bruce, he pointed out that my disbelief in ESP’s existence is a belief in its non-existence. So I’m expressing a belief just as ESP’s proponents are.

Me: But there’s evidence that supports my position.
Bruce: But believers consider anecdotal evidence to be of equal value to scientific testing.
Me: But it’s not.
Bruce: That’s your BELIEF. You believe that the scientific method is the only way to truth. They believe that there are other ways to truth for some phenomenon that science just can’t catch reliably.

Bruce was not necessarily defending ESP’s existence, only arguing for the equality of belief for and against, given different background beliefs in the validity of the scientific method for determining truth. Interesting.

More on that in the next article.

Blind Acceptance

I little while ago I attended a friend's church service. The pastor give an interesting sermon--they call the Message. At one point she said "Just as twins separated by great distances can feel each other's distress, so can ..."

I wrote her a letter. In it I explained that one of my goals as a physics teacher is to have students think, examine, and test hypotheses and claims before accepting them. Many students enter my classroom being firm believers that Earth has been visited by aliens, that we have not gone to the Moon, that ghosts exist, that mysterious disturbances happen in a Bermuda triangle, that people can read minds and move objects by pure thought, and so on. I try to persuade the students to look at these claims sceptically. And here she was talking pseudoscience.

I mentioned to the pastor that there was no reputable scientific evidence that separated twins can sense, for example, when the other breaks an ankle or has a bad dream. I requested that she refrain from stating dubious, unsupported claims as fact(and using them to support her argument).

But this brings up an interesting question: Where do I stop with my request? Obviously, I can't ask her to stop repeating untestable claims about the existence of God. To her God's existence is a fact. I'm trying to be fair to her, here. Regardless of whether I'm believer, agnostic, or atheist, I feel I have to let her state claims about God as facts as she sees them. But I want her to stop stating OTHER unsubstantiated claims as fact.

I think there's a line here that the pastor, priest, rabbi shouldn't cross, but it's a little tricky justifying it.

I am reminded of the requirements for good science fiction. We allow certain breaches of the laws of physics (warp drive; transporter beams; instant communication, perhaps). But having granted this limited latitude, we want consistency with the rest of the known laws of physics. I have a hard time explaining to my wife why I allow one "magic" device but not another. If you are a sci.fi. fan, though, I expect you know what I mean.

(I remember one episode of Star Trek, the Next Generation where Geordi and Ro were in a semi-dead state, or a different dimension, or something ("cloaked and phased", actually, they need the anyon beams to wipe out the chroniton fields!). Anyhow, they couldn't be seen by normal matter (i.e. everyone else). They could run through walls! My 10 year-old daughter saw the inconsistency: If they pass through the walls, she asked, why they didn't fall through the floors!)