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I'm a geologist. This press release is pure BS. We've known beyond reasonable doubt that the inner core is solid for more than a decade - for instance: http://s

I'm a geologist. This press release is pure BS. We've known beyond reasonable doubt that the inner core is solid for more than a decade - for instance: http://science.sciencemag.org/content/early/2005/04/14/science.1109134 http://science.sciencemag.org/content/early/2005/04/14/scien... We even know the elastic modulus of the solid inner core: http://advances.sciencemag.org/content/4/6/eaar2538 http://advances.sciencemag.org/content/4/6/eaar2538

fouc 8y ago
As a geologist, your favorite movie is still "The Core" right?
- cbkeller 8y ago
  Ya, it's a perennial at "bad geoscience movie night"
cbkeller 8y ago
The new study by Tkalčić and Phạm is cool work, but it's not even the first observation of PKJKP, so this press coverage is irresponsible. The "perspective" by Irving accompanying the Tkalčić and Phạm paper is pretty readable and BS-free: http://science.sciencemag.org/content/362/6412/294 http://science.sciencemag.org/content/362/6412/294
wrycoder 8y ago
Thanks. As a general rule, sciencealert isn't worth reading.
- cbkeller 8y ago
  There's a whole interesting dynamic that leads to this sort of press release: whenever someone publishes a high-profile Nature or Science paper, they usually have a chance to work with the university communications department to make a press release which goes to out sites like sciencealert. The writer from the communications department usually wants to hype your paper beyond belief, so it falls to you to talk them down (sometimes repeatedly). But if you talk it down too much, then maybe they won't want to do a press release for your next paper, so less press coverage to cite in your tenure case :/ It's a vicious cycle
marktangotango 8y ago
So why is the earth so old and still incredibly geologically active? Is it simply because of the moon and tidal effects? If the crust is thin relative to other planets why hasn’t the earth cooled more by now?
- nwallin 8y ago
  Radioactive decay of long lived elements in the core. There's a square cube relation between surface area and volume. Smaller planets have much more surface area compared to volume than larger planets. So it takes a lot longer for heat to escape the core. While smaller planets can radiate their heat away relatively quickly, in the Earth it just builds up. Venus is of comparable size to Earth. But we don't know very much about Venus' geology. We know that there isn't any active vulcanism on Venus, its crust is all approximately the same age, and is (in geologic and astronomical terms) relatively young. The speculation is that the hot blanket of Venus' atmosphere actually keeps something of a lid on things. The magna isn't so much hotter than the atmosphere that vulcanism is an efficient means of letting off heat. So it just builds up for millennia (hundreds of millions of years? I do not recall the timescale.) until it reaches a critical temperature where most of the entire surface begins melting/venting/erupting. We can't prove it to any significant extent, but it's the model that best fits the evidence.
- cbkeller 8y ago
  Two reasons: (1) the earth has really huge thermal inertia (2) radiogenic heat production. (2) often gets a lot of the credit (who doesn't like radioactivity), but (1) is probably doing more of the heavy lifting At present day, Earth is losing heat at a rate of about 40 terawatts. This 40 terawatts drives mantle convection, plate tectonics, and every volcano out there. As best we know, about 35% of that 40TW is radiogenic (decay of Th-232 with a half-life of 14 bilion years, U-238 with a half life of 4.5 billion years and K-40 with a half life of 1.25 billion years, among others). A fair amount of the decay energy is actually lost to neutrinos, but the rest is converted to heat and eventually lost by convection or conduction. The other 65% or so is primordial -- essentially, gravitational potential energy from the accretion of the Earth, converted to heat and slowly lost over the past ~4.51 billion years since the moon-forming impact. Earth's bulk thermal inertia (heat capacity times mass) is about 5.6E27 J/K. In other words, cooling the earth by one degree C releases 5.6E27 joules. That's a lot of joules! Even so, there's a bit of a problem because geochemical evidence suggests that the mantle (which makes up most of the earth by volume) has probably not cooled by more than about 150C over the past 3.5 billion years, which means either one of our estimates is wrong, or the core is cooling pretty fast -- this would actually mean that the inner core might be pretty young, like < 1 billion years.
dang 8y ago
Thanks. We've taken that first-time business out of the title above.
Asking4AFriend 8y ago
Let me guess. You also think the world is round and not flat! But seriously, thanks for the additional links and confirming some suspicions.

fouc 8y ago

As a geologist, your favorite movie is still "The Core" right?

cbkeller 8y ago
Ya, it's a perennial at "bad geoscience movie night"

cbkeller 8y ago

The new study by Tkalčić and Phạm is cool work, but it's not even the first observation of PKJKP, so this press coverage is irresponsible. The "perspective" by Irving accompanying the Tkalčić and Phạm paper is pretty readable and BS-free: http://science.sciencemag.org/content/362/6412/294 http://science.sciencemag.org/content/362/6412/294

wrycoder 8y ago

Thanks. As a general rule, sciencealert isn't worth reading.

cbkeller 8y ago
There's a whole interesting dynamic that leads to this sort of press release: whenever someone publishes a high-profile Nature or Science paper, they usually have a chance to work with the university communications department to make a press release which goes to out sites like sciencealert. The writer from the communications department usually wants to hype your paper beyond belief, so it falls to you to talk them down (sometimes repeatedly). But if you talk it down too much, then maybe they won't want to do a press release for your next paper, so less press coverage to cite in your tenure case :/ It's a vicious cycle

marktangotango 8y ago

So why is the earth so old and still incredibly geologically active? Is it simply because of the moon and tidal effects? If the crust is thin relative to other planets why hasn’t the earth cooled more by now?

nwallin 8y ago
Radioactive decay of long lived elements in the core. There's a square cube relation between surface area and volume. Smaller planets have much more surface area compared to volume than larger planets. So it takes a lot longer for heat to escape the core. While smaller planets can radiate their heat away relatively quickly, in the Earth it just builds up. Venus is of comparable size to Earth. But we don't know very much about Venus' geology. We know that there isn't any active vulcanism on Venus, its crust is all approximately the same age, and is (in geologic and astronomical terms) relatively young. The speculation is that the hot blanket of Venus' atmosphere actually keeps something of a lid on things. The magna isn't so much hotter than the atmosphere that vulcanism is an efficient means of letting off heat. So it just builds up for millennia (hundreds of millions of years? I do not recall the timescale.) until it reaches a critical temperature where most of the entire surface begins melting/venting/erupting. We can't prove it to any significant extent, but it's the model that best fits the evidence.
cbkeller 8y ago
Two reasons: (1) the earth has really huge thermal inertia (2) radiogenic heat production. (2) often gets a lot of the credit (who doesn't like radioactivity), but (1) is probably doing more of the heavy lifting At present day, Earth is losing heat at a rate of about 40 terawatts. This 40 terawatts drives mantle convection, plate tectonics, and every volcano out there. As best we know, about 35% of that 40TW is radiogenic (decay of Th-232 with a half-life of 14 bilion years, U-238 with a half life of 4.5 billion years and K-40 with a half life of 1.25 billion years, among others). A fair amount of the decay energy is actually lost to neutrinos, but the rest is converted to heat and eventually lost by convection or conduction. The other 65% or so is primordial -- essentially, gravitational potential energy from the accretion of the Earth, converted to heat and slowly lost over the past ~4.51 billion years since the moon-forming impact. Earth's bulk thermal inertia (heat capacity times mass) is about 5.6E27 J/K. In other words, cooling the earth by one degree C releases 5.6E27 joules. That's a lot of joules! Even so, there's a bit of a problem because geochemical evidence suggests that the mantle (which makes up most of the earth by volume) has probably not cooled by more than about 150C over the past 3.5 billion years, which means either one of our estimates is wrong, or the core is cooling pretty fast -- this would actually mean that the inner core might be pretty young, like < 1 billion years.

dang 8y ago

Thanks. We've taken that first-time business out of the title above.

Asking4AFriend 8y ago

Let me guess. You also think the world is round and not flat! But seriously, thanks for the additional links and confirming some suspicions.