Exploring Nature’s rarest phase

(Photo by Umberto Salvagnin)

(Photo by Umberto Salvagnin)

With streams freezing up, we’re temporarily losing something very special – something incredibly rare in the universe: an environment with liquids!

The wonderful-but-often-colorized images from Hubble, and the striking stuff viewed through a backyard telescope, are always solids like the Moon or gases like nebulas. The Sun and stars are sort of gaseous, too: a special kind called plasma where their atoms are broken to pieces.

But liquid? That’s matter’s most unusual state, discounting the odd Bose Condensate that only happens near absolute zero in earthly labs. Liquid’s rarity is not immediately obvious because of our bias: We live on a world with a mostly liquid surface, and use brains made largely of fluids. We feel our hearts pumping liquid throughout our bodies. We’re comfortable with it.

But liquid is actually very unusual. First off, you can’t even have liquid in space. When a comet, a ball of dirty ice, comes close to the Sun, that ice doesn’t melt but instead sublimates – changes directly from solid to gas.

That’s because liquids can only exist under pressure. And they need a very narrow temperature range, too. By contrast, solids and gases survive anywhere: where it’s hot, cold or even in the vacuum of space.

That you need a pressurized environment to see fluids at all means that none could exist on the Moon. Here on Earth, a thick atmosphere supplies this pressure, as does the ice sheet on Jupiter’s moon Europa, allowing deep oceans there.

As Lava Lamps have proven since 1965, liquids are psychedelic and fascinating in a way that solids can never match. That whole flowy thing is a kingdom all its own. But what exactly are liquids?

Believe it or not, there is still some mystery to this. We can say for sure that a substance whose atoms make a crystalline pattern, or one that retains its shape against gravity, is a solid. By contrast, substances whose individual atoms or molecules are free to float independently are gases. We know that liquids are somewhere in between, and generally define liquid as something that can and will change shape completely. Tip an open container on its side and a liquid will sooner or later flow out.

But this is a descriptive definition rather than a scientific one. The problem is that there are so many exceptions and odd cases. Are gels solid or liquid? What about liquid crystals and foams? Silly Putty? What about glass? The latter acts like a solid, but doesn’t have either a crystalline structure or a precise melting point where you can say that it’s now precisely changed from a solid to a liquid. (Cold glass does not flow or change shape over centuries, contrary to myth.)

One further reason why liquids fascinate us is that there are so few of them around us in nature. Disregarding things like milk that are simply water containing dissolved or undissolved solids, we don’t stroll through the woods and encounter pools of disparate liquids. Water is it. We’ve all seen or handled alcohol, oil, kerosene and mercury, but they come packaged in man-made containers. They’re not naturally dripping into pools around us, and there’s not a great variety like the myriad of diverse solids and even gases that make up the natural world.

This leads to the Cassini lander’s surface pictures of Saturn’s moon Titan. There, methane or natural gas takes a liquid form on its cold pressurized surface. It’s the first and only surface liquid that we’ve seen in the entire universe, beyond Earth.


Answers to last week’s puzzles

Note: These puzzles’ solutions each revolve around an absence of information, as in Sherlock Holmes’s reasoning regarding “the dog that didn’t bark.” The fun is figuring them out. So don’t just read the answers if you haven’t tried the puzzles. In case you missed the last edition of Almanac Weekly, you can find the puzzles on our website here: https://www.hudsonvalleyalmanacweekly.com/2016/01/17/the-adoration-of-the-unknown/.

Puzzle One:

Her hat is black. She’d heard the rearmost woman say that she didn’t know which hat she was wearing. This means that she couldn’t be seeing both women in front of her wearing white hats, because then she’d have known that hers must be black, since there were only two white hats altogether. She was thus seeing those women wearing either two blacks or some combination of one black and one white.

The middle woman, hearing this and now knowing that she and the woman in front of her couldn’t both be wearing white hats, now must be seeing the one in front of her in a black hat. After all, if she saw a white hat, she’d know that hers must be black. But since she now says out loud that “I cannot tell what color hat I’m wearing,” the woman in the front – the only one who can see no hats at all – realizes that the woman behind her must be seeing her wearing a black one. That would be the only reason she can now say, “I can tell what color hat I’m wearing!”

Puzzle Two:

This one’s tougher. Both women know what number apartment they once shared, and thus they both know the sum of the children’s ages. But we, the readers, do not. We do know that the product of their ages is 36. However, working it out, we see that there are eight possibilities for their ages – for example: 18, 2 and 1; 3 and 3 (twins) and 4; and 12, 3 and 1. How can we narrow down which of these eight is the reality? We cannot. But the second woman, who knows the sum of their ages, should be able to.

The sums adds up to various integers; in just the three choices just cited, the sums are 21, 10 and 16. Which of the eight is correct? We don’t know, but the second woman should know, since she knows the sum, and hence the correct choice among the eight possibilities. Yet she says, “That’s still not enough information.”

That single line, expressing a lack of information, is the key to solving the puzzle. The key is to ask yourself: “Why doesn’t she know? She ought to have enough information!”

So the next step is looking over the eight possibilities, and then one sees that the sums variously are 38, 16, 21, 12, 13, 11, 10 and 13. Those are the three-way choices whose product is 36. But look: Two of the choices have an identical sum – 13. These are 6, 6, 1 and 9, 2, 2. Since she now says that she still doesn’t have enough information, the only possible explanation is that the answer must still be ambiguous, which means that it must be one of those two. But she has no way to decide between them.

So her friend now says, “The oldest one has brown eyes.” In the two choices, only one of them involves an “oldest one,” since the other choice contains older twins. The age of the three children is thus known: 9, 2 and 2.


Want to know more? To read Bob’s previous “Night Sky” columns, visit our Almanac Weekly website at HudsonValleyAlmanacWeekly.com.

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