Today’s factismal: There is not “a hidden ocean in the Earth’s mantle”.
One of the problems with the internet is that nobody knows you’re a dog; the information provided by experts is given the same weighting as the nonsense spewed out by “experts”. And because those who know nothing about a topic are frequently the ones who say the most (witness the arguments over settled science such as evolution or climate change), good information is frequently overwhelmed by bad or misleading memes. One of the most egregious sites for these erroneous ideas is IFL Science (in general, any site that uses curse words in its title is unlikely to provide actual information) which is attempting to be the Discovery Channel of the internet (this is not a compliment).
As an example of the quality of IFL Science’s contributions, consider this one: Found! Hidden Ocean Locked Up Deep in Earth’s Mantle. This particular piece of wretched journalistic excess first appeared nearly a year ago but it has been resurrected as all things are on the internet. In the author’s deathless prose, he gushes about the search for a “deep reservoir for water” in a part of the mantle known as the transition zone. Though the author does eventually point out that the “water” is actually hydrogen and hydoxyl ions that are chemically bound to the mantle material, that only happens after he makes the misleading claim that there could be three ocean’s worth of water in the mantle.
Why is the claim so misleading? Because he provides absolutely no context for the statement and it gives people the idea that the water is in some huge, interior ocean. Yes, there could be enough “water” in the deep mantle to fill the oceans three times over. But what is left out is that the mantle is so large that the water makes up just 0.0001% of the mantle’s mass and it is spread out rather than being concentrated as a specific reservoir. To put it another way, if you were to fill up an Olympic swimming pool with dry sand and then pour a two liter bottle of water over the top, that is how “wet” the mantle would be and about how concentrated it would be.
And the problem with the hyperbole is that it distracts from the important part of the research. You see, the mantle is almost completely solid. The upper-most 7% of the mantle, known as the aesthenosphere, is the most molten part with up to 5% melt (about the same as in a chocolate-chip cookie fresh out of the oven). But the rest of the mantle is almost completely solid. However, over long time frames, the mantle will flow. To understand how a solid can flow, consider ice cream or fudge; both of them are solid but will flow under enough pressure and heat. And if there is water in the mix, it can change the amount of pressure or heat needed to make the mantle flow. And that’s what the scientists discovered. Just having a touch of water in the mantle allows it to partially melt (remember that cookie?) and lets it flow more easily.
So the next time that you see a science meme, look to see where it comes from. And if it is from a site that doesn’t know the difference between discourse and dis curse, just ignore it. Trust me – you’ll be happier and better informed!