The Morning After: Scientists confirm a fifth layer inside the Earth's core:
[...] A team at Australian National University (ANU) has found evidence of a new" fifth layer to the planet, an iron-nickel alloy ball in the inner core. The scientists found the hidden core by studying seismic waves that travel up to five times across the Earth's diameter – previous studies only looked at single bounces. The earthquake waves probed places near the center at angles that suggested a different crystalline structure deep inside.
The ANU researchers also believe the innermost inner core hints at a major event in Earth's past that had a "significant" impact on the planet's heart. As researchers told The Washington Post, it could also help explain the formation of the Earth's magnetic field. The field plays a major role in supporting life as it shields the Earth from harmful radiation and keeps water from drifting into space.
Bouncing Seismic Waves Reveal Secrets of the Planet's Inner Core
Data captured from seismic waves caused by earthquakes has shed new light on the deepest parts of Earth's inner core, according to seismologists from The Australian National University (ANU).
By measuring the different speeds at which these waves penetrate and pass through the Earth's inner core, the researchers believe they've documented evidence of a distinct layer inside Earth known as the innermost inner core – a solid "metallic ball" that sits within the center of the inner core.
Not long ago it was thought Earth's structure was comprised of four distinct layers: the crust, the mantle, the outer core, and the inner core. The findings, published in Nature Communications, confirm there is a fifth layer.
"The existence of an internal metallic ball within the inner core, the innermost inner core, was hypothesized about 20 years ago. We now provide another line of evidence to prove the hypothesis," Dr. Thanh-Son Phạm, from the ANU Research School of Earth Sciences, said.
Professor Hrvoje Tkalčić, also from ANU, said studying the deep interior of Earth's inner core can tell us more about our planet's past and evolution.
"This inner core is like a time capsule of Earth's evolutionary history – it's a fossilized record that serves as a gateway into the events of our planet's past. Events that happened on Earth hundreds of millions to billions of years ago," he said.
The researchers analyzed seismic waves that travel directly through the Earth's center and "spit out" at the opposite side of the globe to where the earthquake was triggered, also known as the antipode. The waves then travel back to the source of the quake.
(Score: 2) by Mojibake Tengu on Tuesday February 28, @11:55AM (9 children)
As the vector of gravity at the center of gravity of whole Earth body is limit-computable as zero, total pressure over there must zero too, and material density must be distributed (by gravity of said material itself) around it, the "core" is hollow, by centrifugal force overcoming zero gravity.
The same logic applies to stars. Stars are hollow too.
Both Geophysics and Astrophysics are completely wrong.
The edge of 太玄 cannot be defined, for it is beyond every aspect of design
(Score: 2, Insightful) by khallow on Tuesday February 28, @02:01PM
Two things: first, it's non-zero once you deviate even slightly from the center of gravity, and second, there's 6000 km of stuff on top of that center point, all pressing in. So it's the highest pressure point not the lowest.
Good thing you're there to set things straight. Have another beer.
(Score: 3, Interesting) by RS3 on Tuesday February 28, @02:58PM (1 child)
Interesting hypothesis, I've never heard that before. So are earth's total mass calculations wrong? Like maybe all planets and stars are hollow and all astrophysical calculations are just plain wrong?
Or earth's density? Like maybe there's more tungsten or some other more dense metal in the sphere outside of the hollow core?
Inside of the hollow sphere is what? Pure vacuum? Some gasses? Vapor??
I would think this could be modeled mathematically. I'm not up for it, but I used to know some physicists... oh, I do know a physics / astrophysics prof. I'll get in touch with him. I know he'll have an answer. I'll post back when I hear from him...
(Score: 2) by RS3 on Tuesday February 28, @03:08PM
I'm going to think / sleep on this before I write to physics prof. When doing thought experiments, I usually like to take things from one extreme to the other. Imagine the smallest free-floating ball of "stuff" floating in space. No matter how small, the molecules attract each other. Even a water droplet falling in a vacuum stays together, no hollowness. No time for this now...
(Score: 3, Insightful) by sjames on Tuesday February 28, @04:05PM
It's an interesting thought, but further analysis should show it to be a dead end.
The centrifugal force near the center will be insignificant since it's still rotating at about 0.0007 RPM (1 revolution per day). That leaves the pressure of all the matter above practically unopposed. Actually, the micro-gravity in that region is enough to oppose the micro-centrifugal force such that if the bulk of the earth was magic-ed away it would still form a solid sphere.
(Score: 2) by istartedi on Wednesday March 01, @12:05AM (2 children)
Imagine two balls, half the diameter of the Earth, and you're positioned right between them. You'd be crushed between them due to gravitation. The balance of the material that would make up Earth doesn't help you either. In fact, it hurts quite a bit since it can be approximated as huge wedges with you pinched between the sharp edges at the bottom.
Or another way of thinking about it, you're at the bottom of the gravity well and it's crushing.
Yes, there is some counter-balance due to rotation but it's negligible. Gravity dominates, and the core is every bit as solid as we think.
You could work through this all as a calculus problem too, and find that the maximum is in the center. As a thought exercise, consider a descent in to the depths of the ocean where we know pressure increases the deeper you go. If the Earth were nothing but water, at what point would the pressure start to decrease, and why? Calculate it. Show us how you set up that equation and what the result is.
Appended to the end of comments you post. Max: 120 chars.
(Score: 2, Funny) by Anonymous Coward on Wednesday March 01, @02:27AM (1 child)
Screw all that homework you suggest, I just asked ChatGPT like any student should:
So there.
(Score: 2) by istartedi on Wednesday March 01, @03:11AM
At this depth, the pressure would reach zero and then start to decrease again.
Literal LOL. Thank-you so much.
Appended to the end of comments you post. Max: 120 chars.
(Score: 2) by maxwell demon on Wednesday March 01, @04:26AM
And I guess all high-pressure containers are actually empty, too, because there's no way their gravity can sustain the large pressure, right?
The pressure at the core is caused by all the surrounding matter pressing inwards. If there were zero pressure at the core, that would mean material from surrounding the center, which clearly is under pressure, would flow in, until the pressure is actually the same as the surrounding pressure. Indeed, even the air pressure adds to the pressure in the center, although that is negligible compared to the pressure from all the rock.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 2) by RS3 on Tuesday March 07, @04:27AM
I did cross paths with aforementioned physics professor (dept. head, smallish Uni). I asked him, sheepishly, about the hollow core idea and he immediately poo-pooed it. We didn't have time to talk further, but a bit later I asked one of the smartest people I know, who is pretty good with all things physics, and he instantly said if the earth were spinning fast enough to create a core vacuum, we'd all have been flung off long ago.
Remember, the closer you are to the rotation axis, the less the apparent "centrifugal" force on you, so gravitational attraction keeps everything together. Stated another way, the farther you are from the axis, the greater the "centrifugal" force.
In fact, earth is a bit fatter around the equator. "Earth's equatorial bulge is about 43 kilometers." So, not a lot, but makes sense (to me anyway) considering the very slow rotation speed.
It might be a frame of reference thing. If you're talking about your weight as measured by the force of gravity in one direction, pulling you downward, then I understand the confusion. Yes, the further you go into the center of the earth, if you could do such a thing, the less your apparent weight would be if you were standing on a scale. But, you'd be under more and more pressure as everything around you is gravitationally attracted to everything around you. So at the center you'd be pulled in all directions, but you'd be under enough pressure to keep you intact. Maybe a bit too intact.