By measuring the speed of the waves at different depths, the team could figure out which types of rocks the waves were passing through. The water layer revealed itself because the waves slowed down, as it takes them longer to get through soggy rock than dry rock.
Jacobsen worked out in advance what would happen to the waves if water-containing ringwoodite was present. He grew ringwoodite in his lab, and exposed samples of it to massive pressures and temperatures matching those at 700 kilometres down.
To me, as someone who knows not that much about all this, that sounds like it could well be hooey. It could be voodoo. It could be a Tall Tale.
Can anyone explain to me (like I am 5 years old) how such things get vetted or taken seriously or whatever?
Suppose you have an earthquake at a known location, or you set off a large underground explosion at a known location. This causes several different kinds of waves to radiate out from that location.
Seismometers can detect those waves. How fast the waves of a given type move depends on the kind of rock or soil they are moving through. When we measure how long the wave took to go from the point of origin to a given seismometer, that tells us a little bit about the kind of rock or soil on that wave's path. The wave might have passed through many different kinds of rock or soil, so just looking at one wave doesn't tell much--just that the path had some mix of rock and soil overall that gave that speed.
We aren't limited to one wave, fortunately. Every time something generates detectable waves, we get a little more data on the composition of the rock and soil on the paths between that source and every seismometer that measures those waves.
The more data we get, the more constraints that puts on what kind of rock and soil can be where and still be consistent with all of the observations.
For things reasonably near the surface the deductions from seismic wave analysis can be checked against observation from tunnels and wells to verify that the methods work.
Observing how waves travel through planetary bodies is one of the most useful methods for looking into the interior of these objects. On a fundamental level, it's an advanced version of knocking against a large metal silo to determine if it's empty or full.
However, detailed findings can be tricky sometimes. In this case, the geologist calculated beforehand what the frequency absorption fingerprint of "rock containing water" would be, and then he found a matching signature in the measurements he took.
Indeed there are several things that could have gone wrong: the signature of the substance might be different than previously assumed, or the seismic measurements themselves could be faulty.
Over time we'll get more measurement opportunities and we'll refine our models as more scientists will work on this. There might be more evidence from other sources available if we know how to look for it, too. So the confidence level in this finding will be modified in the future.
Right now it's just an intriguing but singular result that deserves further study.
Right now it's just an intriguing but singular result that deserves further study.
See, I guess that is my issue here: The article talks like we KNOW this for sure, not like "preliminary results suggest..." when no one has sampled anything that deep to verify it etc.
What are you asking to have explained, the science? Like, how seismic waves propagate at different speeds through materials of different densities? Or how the observed propagation of seismic waves through the planet after multiple earthquakes had anomalies that matched those predicted in the presence of "wet" (hydrous) ringwoodite? Or how they created ringwoodite in the lab and subjected it to temperatures and pressures like those that might be found in the mantle?
Have you ever seen the beginning of the movie The Core? Just about the only real bit of science in it is that sound travels differently through different materials in the mantle.
To be vetted, an experiment will be peer reviewed by others for obvious mistakes, compared to existing results and mathematical models, and duplicated by others.
I don't mean to be demeaning, but in situations like this, admitting your ignorance on a subject is a great first step, but the next is learning how to best phrase questions.
Here, you would be better off asking about the parts you don't understand such as how they came to their conclusion, or how their reasoning considering the article works.
By measuring the speed of the waves at different depths, the team could figure out which types of rocks the waves were passing through. The water layer revealed itself because the waves slowed down, as it takes them longer to get through soggy rock than dry rock.
Jacobsen worked out in advance what would happen to the waves if water-containing ringwoodite was present. He grew ringwoodite in his lab, and exposed samples of it to massive pressures and temperatures matching those at 700 kilometres down.
To me, as someone who knows not that much about all this, that sounds like it could well be hooey. It could be voodoo. It could be a Tall Tale.
Can anyone explain to me (like I am 5 years old) how such things get vetted or taken seriously or whatever?
No, I am not trolling.
Thanks.