I’m Not Listening

Why does a snorer never hear him or herself? The noise can be truly awesome, as any victim can attest, and I’m at a loss as to how anyone can sleep through the echoing thunder coming from the pillow next to our own. Why are we the only ones to hear it? Why can’t the snorers?

Dr. Meir Kryger, Professor of Medicine at the University of Manitoba and Director of the Sleep Disorders Centre at the St. Boniface Hospital Research Centre in Winnipeg:

This listener is going through something that many people go through, and it can certainly seem mystifying that a snorer can sleep through the tremendous racket they make. The explanation lies, of course, in our brains. Our brain basically ignores information that it doesn’t consider important. The snorer’s brain just decides that the noise from its own snoring is not going to wake it up.

We used to think that the sleeping brain was basically in neutral, idling and not doing much. All sorts of experiments have proved that this isn’t the case, that the brain is extremely active during sleep. We know that it is “hearing,” but that it does a lot of filtering and signal processing, so that it will only respond to the kinds of sounds it knows are important. Mothers, for example, become sensitive to the softest cries of their babies when they need to be fed, but will ignore the louder noise of an airplane flying overhead at four in the morning.

A lot of this filtering is going on in a region of the brain called the thalamus. We don’t understand the mechanism, though, and we certainly don’t understand how the brain decides what’s important and what’s not important. It is a quite amazing ability. Snorers can reach eighty decibels, louder than a barking dog, and sleep through the whole thing. When you play them a tape of themselves snoring, they can’t believe they are able to sleep through it.

Of course, an interesting question is, if the snorer’s brain can ignore the noise, then why can’t the brain of the person lying next to them do the same thing? The answer is that it can and often does. Snoring is very common, especially in Canada, it seems. In a study done in Toronto several years ago, about 80 per cent of wives claimed that their husbands snored. Other studies from around the world have found that about 30 per cent of adult men and about 15 per cent of women snore. There would be a lot of sleep-deprived women and men out there if they could not adapt to their partner’s snoring. Studies have shown that if the bed partner can fall asleep before the snorer, she or he will very often sleep through the snoring. However, the bed partner who doesn’t fall asleep before the snoring spouse may be doomed for the night, since the unconscious mind seems to be better than the conscious mind at filtering out that infernal racket.

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Sticky Feet

Why don’t flies fall off the ceiling?

Dr. Hugh Danks, Entomologist with the Canadian Museum of Nature in Ottawa:

The first thing to note is that flies are light in weight and they’re small in size. They have an external skeleton that is relatively light, and, in contrast, humans have a heavy internal skeleton made of bones. If we were to try to hang from the ceiling, we would need some pretty sophisticated hardware. But flies are light, so they don’t need the hardware. They are light enough that they aren’t really fighting much gravity to stay suspended.

Flies use tiny pads on their feet to hang from the ceiling. Each foot has a couple of claws, mainly used for hanging on to rough surfaces, and two tiny pads that allow them to attach themselves to smooth surfaces. We are not certain how these pads work, but there are very minute hairs on the pads and an oily secretion. It seems that, when the pad is applied to a surface, molecular forces, in effect, stick the fly to the surface and keep it there. There are really micro suction pads on the bottom of their feet.

Staying on the ceiling is a balancing act between the pads being so sticky that the fly can’t release from the surface, and not sticky enough to hold the fly up. But luckily for the fly, it is light enough not to need a very strong glue, and, along with the action of the pads, its walking and flying strength can break the bonds with the ceiling when it wants to move its feet. The system works well enough that many insects use it. It is a pretty common strategy.

As well as walking on the ceiling, a fly has to get there in the first place. How it does that is an interesting question that was solved a number of years ago using high-speed photography. Flying upside down is a bit of a trick. You might think that flies would do a barrel roll like an airplane, so they would first turn upside down and then land on the ceiling. But if they’re upside down, both their wing action and gravity are pulling them down, so flies have developed a different strategy. As a fly gets close to the ceiling, it flies in at an upward angle, and then touches its front feet to the surface. When the front feet touch down, the fly’s momentum pivots it over its front feet and it flips over to land upside down. It is like a trapeze artist with his hands on the bar, whose feet flip up at the highest point in the arc.

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Lost at “c”

If one were to travel vast interstellar distances at a rate faster than the speed of light, would we be able to see much along the way?

Dr. Ann Gower, Professor of Physics and Astronomy at the University of Victoria:

According to the laws of physics, as we understand them, it is not possible for us to travel at the speed of light, let alone faster, so there isn’t really an answer to this question. What can be answered is what you would see if you travelled through the galaxy at very close to the speed of light.

First of all, looking out the front window, any light from stars in front of you would be shifted to shorter wavelengths, or blue-shifted, because you’re moving so fast. If you were going very fast indeed, really close to the speed of light, the light would be shifted out of the visible range completely, into the X-ray or gamma-ray wavelengths. Very high energy radiation would be hitting you very hard from straight ahead. It would be really dangerous, and you would likely be baked!

But whereas the light from stars in front of the ship would be blue-shifted, the opposite would happen behind you. The light from those stars would be red-shifted to longer wavelengths. These would be below our visible range, right down into radio wavelengths, so they would be invisible to the naked eye. This means the sky behind us would be dark, without much to see.

When you looked out the sides of the ship, you would also see very little. There is a very dramatic effect on the geometry of space, due to relativity, when you travel close to light speed. If you’re going very fast, the stars will appear to be bunched close together in front of you. Everything will be compressed into a cone ahead of you, in the direction you’re moving. It is rather like driving in a shower of rain. When you drive through a rainstorm, it looks as though all the drops are coming from the front. The same effect would happen in a spaceship as you approached the speed of light, but it would be much more extreme. All the stars would appear to be in front of you. So you’re not going to see much out of the side windows.

Light waves aren’t the only thing affected by travelling close to the speed of light. The universe is filled with cosmic background radiation, left over from the Big Bang. Like the light, the energy from the cosmic radiation would appear blue-shifted in front of the ship, making it much hotter and more energetic. It would become another source of X-rays raining down on the ship. Added to the light from the stars, it would create a very high energy situation!

Another form of energy, which we know must exist throughout the universe, is gravity waves. We haven’t yet detected them, but we know they are there. These will also be intensified. As you travel closer to the speed of light, you would feel them as stronger and stronger bumps. So, even if you survive being baked by the shifted starlight and background radiation, you are liable also to be shaken violently by intensified gravity waves. Perhaps we could call it “shake and bake” travel!