The mountains and the sea, Part 1

Rummaging through my closet, I came upon my old professor hat.  Thought I’d put it on, and write a bit about sea level.

If you’re a hiker, you’re familiar with those USGS topo sheets showing, among other things, terrain relief.  You probably also know those numbers you see on the elevation lines are all measurements of the vertical distance to sea level.  Even if you’re not into hiking, you might know the elevation of some mountain, or the highest point in your state, or the levee down by the river; same thing for them, measured above sea level.

You probably also know that the sea level is rising.  What does that do to all those numbers?

Well, nothing, actually.

It might seem that the level of the sea used to be constant, and any change is pretty recent, but there have always been fluctuations, both on a local and a global scale.

Think about something as seemingly simple as determining sea level at any given point on a shoreline.  Do you measure it during high tide or low?  Full moon or new?  What about those little ripples  of waves lapping the shore; is your measurement going to be taken at the maximum encroachment or the minimum?

Okay, fine, you say, measure all those points and use the average.  That, in fact, was originally what was done, which is why the official elevation was always given as distance above mean sea level.  Unfortunately, that doesn’t fix things.  Because, you see, you have to ask yourself, mean sea level exactly where?  The solution was to take means at various points, and average those, and so on.

What developed was a convention in which a statistical mean was taken as sea level, which didn’t correspond to actual sea level anywhere in particular.  At this point, sea level was already an abstraction, but some respect was still given to the original concept, and means were kept as close as possible to actual sea levels.  But it turned out that if you used a global mean, the numbers were too far off.  In the end, we got elevations taken with respect to various regional reference points, or datums, around the world: the North American datum, the European datum, and so on.

Confused?  How can sea level differ so much around the world?

First of all, the earth is not a sphere; it’s more like a lumpy egg.  As a result, early suggestions to use the center of the earth as a reference were useless.  Furthermore, water is not even level with respect to local elevations.  Lake Huron, for example, is 5 centimeters higher at the south end than at the north end.  This is partly due to the direction of water flow, but also in the difference in composition of what’s under it.  The iron-rich substrates in the north are denser, and therefore exert a greater gravitational pull.  These effects are compounded globally.

The result is the so-called equipotential system of sea level.  Rather than using the physical measurement of the distance from a point above another point, mean sea level is now defined as an imaginary surface on which every point measures the same gravitational pull.  The only concession to the actual level of the sea is in the name.

Of course, that used to be a very hard thing to measure.  Thank goodness for GPS satellites.

(to be continued)

Time and the swelling tide

I was just out walking in the town I live in.  An unseasonably nice day, warm and breezy, like the best days of early fall.  Then it hit me: my generation may very well be the last to experience habitable climates on most of Earth.

It is almost certainly too late to adopt enough changes to avoid disaster.  As for our social preoccupations, they are vexing, for sure, but not nearly on an order of magnitude comparable to environmental issues.  No matter how our current crises play out, how sordid or how sublime our responses to the xenophobia raging across the planet, it will all take its place in history, alongside all the ages, dark, golden, or forgotten.

If there still is history.  If the effluent we keep pumping into the air leaves us with a future, let alone history.

In a way, it’s a self-correcting problem.  Either we correct our course, which seems increasingly unlikely, or we render our planet inhospitable.  In either case, our cultures will change, and our sheer numbers will decrease, in the former case by intelligent design, in the latter by brute force.  The earth will return to its inanthropic cycles, none the worse for wear, to whatever state counts as normal.

We are far too young a species to grasp what that is.  Earth has passed through phases as diverse as completely covered with ice, an atmosphere poisonous to virtually any life, and desiccation more severe and universal than anything since we crawled out from our ancestral apes into the brave new world.  Through most of it, life had yet to occur, much less evolve, and even when it had, it clung tenuously to existence.  At least five times since it’s emergence, life has been almost wiped out.  Even our own species was squeezed through a fine and narrow filter some 60,000 years ago, when genetics point to a breeding population of Homo sapiens of less than 2,000.  Some scholars speculate that it was during this period that our evolving intelligence was given a swift kick to accelerate it, in response to the demographic crisis.

Given how that is turning out, I’m not very optimistic.  I hope I’m wrong.

C

I don’t get it. C, that is. The speed of light.

I get that it’s supposed to be constant, and I get that the idea enables us to have GPS and all kinds of other wonderments, and I don’t even wonder why, since the universe gets to have any rules it wants, as far as I’m concerned. I just don’t get what it means that the speed of light is constant. Not light itself, mind you, but its speed. An attribute trumps the thing it’s attached to.

When you’re talking about speed, the first question that pops up is, relative to what? With light, it doesn’t matter, it’s the same regardless of what it’s measured against. If I’m standing still, and you’re moving, we will still get the same reading on our cosmic radar guns. As if that weren’t enough boggle for one topic, yours would arrive a little bluer or redder than mine, because, of course, the frequency, which I would have thought had some relation to speed, is not constant.

What exactly was Einstein on about when he was talking about the speed of light? Clearly, velocity, almost by definition, is what relates time to space, so I get why it should have a central place in a theory that regards space-time as a continuum. But velocity is an attribute, dammit! It has no existence outside of the thing it is a characteristic of. How can it possibly be the root phenomenon of reality as we know it?

Then again, I still don’t understand airline pricing, so maybe such things are just beyond my grasp.

Wilderness revisited

It’s a crazy world.  The other day, I decided to go for a walk; it was the first gorgeous day after a period of rain, and utterly irresistible.  I ended up at the city library, one of those Carnegie structures so ubiquitous in small and medium towns across America, a millionaire’s atonement for ravaging society, back when such people even cared.  This particular one sits in a little park with a bandstand and a monument to a parents’ grief for their soldier son, killed in action.  It has the added virtue of offering coffee from one of those Keurig pod machines for fifty cents.  Pretty good coffee, too, and you get entertained by the myriad characters that hang around such places.

It was, as I said, a beautiful day, so I took my coffee outside, to sit by the fountain donated by another benefactor to the glory of his family.  It was windy, so it was just as well the fountain was off.

Just as I settled in, I heard an animal running somewhere behind me, a large dog, I thought.  As it passed in front of me, though, I was startled to see a young deer bounding headlong toward the midday traffic.  It’s not a huge town, but the streets along the park run to four lanes, and I worried that the deer wouldn’t make it without getting pancaked against a cement truck.  No problem.  In a flash, it cleared six lanes, including a side street, and disappeared into an adjacent church parking lot.

Now, those with a mystical bent might see an omen of some kind here.  Me, I just reflected on the fact that our town, these days essentially just a suburb of St. Louis, has grown very rapidly, outstripping its sleepy county seat days, and leaving nearby wildlife precious little room for, well, wild life.  Ironically, as habitat shrinks, so does the taste for hunting among the minions of the town, now pretty much gentrified and unused to killing their own food.  Canada geese, which used to pass here twice a year during migration, now stay year round in the many ponds dug for all the wilderness-sounding suburbs (Iron Mountain Lake, Notting Hills Forest, etc.).  People complain about the scat, but eating the birds is illegal, so they thrive.  As do wild turkeys, of all things, frightening toddlers in their own yards.

This is happening all over the country, as demographic studies continue to show the increasing urbanization of America.  At least we don’t have bears where I live; that would, indeed, be a portentous omen.

I suppose the upshot is that wherever you might find omens, there is usually a practical element involved as well.  I’m reminded of a student I had while doing archaeology on the island of Ithaka, in Greece.  It was, of course, the home of Odysseus, and we were at the foot of Mount Aetos.  My student, who was supposed to be paying attention to a prism pole he was holding, looked up and cried, “Hey, what kind of bird is that?”

I looked where he was pointing, to his left.  “It’s an eagle,” I said, “and it’s to your left.  According to Homer, that’s a bad omen.”

“Oh,” he said, and turned around until it was on his right.

 

Damn that Galileo!

I find myself thinking about Galileo, for no apparent reason, and his famous Tower of Pisa experiment, which he may or may not have actually performed.  You know the one: dropping two balls of unequal mass simultaneously to show that acceleration due to gravity is independent of mass.  In short, the two unequal balls arrive at the earth at the same time.  In physics, this is an example of what is known as the Weak Equivalence Principle (WEP), which I point out only for the pleasure of using such a silly term.

Despite being undeniably true, this is, to me, counterintuitive.  Think of the implications.  Suppose you are in the vacuum of space, maybe took a wrong turn on the way to the coffee shop, or something.  About ten feet away is a softball.  According to the WEP, you and the softball will move towards each other at exactly the same rate as you and the earth, if it were ten feet away.  Lucky for you, though, the damage inflicted by the softball will be considerably less than that inflicted by the earth in a similar situation.  Okay, the softball is much smaller and has much less mass than the earth, so what’s my point?

Let’s substitute something else for the softball, say, the moon.  By the magic of imagination, retracing your steps to see how you missed the coffee shop, you find yourself ten feet from the moon.  Once again, you and the moon move together at that same rate, independent of mass.  This time, though, you will definitely feel something when you finally make contact, because the moon is much, much bigger than a softball.  (Never thought you’d see that phrase in print, did you?)

We’ve all seen that footage of Neil Armstrong bouncing about on the moon.  I love that little tune that he sings, by the way.  Anyhow, it’s apparent that jumping that high on earth would result in much more jarring to the body.  But the moon, though smaller than the earth, is easily sufficiently massive to stop you cold when you hit it.  Remember, starting at ten feet away, you will strike the surface of the moon at exactly the same speed as you would on earth, coming to a full and immediate stop in both cases, or as close to full and immediate as measurable.  So why is there more damage to your poor, unsuspecting body when you do it on earth?

I remember reading a variation on this question years ago, in some “Ask the Scientist” thingie: if two cars of identical mass collide, how is the force different from one of those cars hitting a stationary wall?  Mr. Scientist, no doubt sighing inwardly, patiently explained that it had to do with the momentum of both masses.  To get the same force with just the one car, it would have to be going twice as fast, and even the thickest of us can see the difference there.  But what if you substitute a mountain for the wall?  Or drop the car from a sufficient height so that it’s going the same speed at impact as in the collision with the wall?  Even double the speed, to take account of the second car?

Or jump off a ten foot platform on the moon?

Don’t mind me; I still can’t see why levers work; and don’t even bring up pulleys.

Saints preserve us!

Pope Francis has put two of his predecessors, John XXIII and John Paul II, on the fast track to sainthood.  Well, alright, for all I know, they were fine people, and maybe deserve some recognition.  Setting aside for the moment the question of all the millions of other fine people who were their contemporaries, but not popes or even Catholics, I have a major quibble with the reasoning here.

According to the ancient rules of such things, to even get this far (beatitude) there has to have been an attested miracle.  This can vary widely, from healing the sick to simply not rotting in the casket.  In the case of John Paul II, there have been two alleged miracles, both involving inexplicable cures from incurable medical conditions after praying to him (while dead, of course) to intercede with God on behalf of the plaintiffs.

Here’s what’s weird.  Presumably, had JP II not been in heaven, all those pleas for intercession would have been for nothing, and the women involved would still be sick today, if they hadn’t died first.  But according to the Church, God is perfectly just.  The whole thing seems to resemble a lottery, in which your health depends not on medicine, or even on your personal faith or the extent of your prayers, but on whether you guessed right as to the eternal disposition of some dead person.

Of course, this is just a minor quibble, in the face of the idea that God, presumably the creator of the universe and hence all of the laws of physics, will suspend those laws on the request of someone from earth.  And not do it for anyone who doesn’t ask nicely, or even for the vast, vast majority of those who do.

Mysterious ways, indeed.

Into the wild

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Today, while wandering through the beautiful campus of Southern Illinois University – Edwardsville, I had the rare privilege of stumbling upon a herd of bicycle, gamboling on a hillside.  I quickly snapped a photo; I apologize for the focus, they were gone in a flash.  Still, I was able to notice a few thing that might be of interest.

As you can see, unlike their domesticated cousins, wild bicycles all have the same distinctive markings; I didn’t see any exceptions.  In addition, there was no size differentiation, such as we are used to seeing.  This is not really surprising; compare dogs and wolves, for example.

But the most notable thing was their joyful abandon, capering through the campus.  I wish we could re-instill that feeling in the domestic bicycles we all love!