Freshly made plutonium from outer space found on ocean floor
npr.org
npr.org
https://en.m.wikipedia.org/wiki/Silurian_hypothesis
Granted it is just a hypothesis but it is an interesting idea.
There is a nice curious droid video on the topic whether a humans if they went extinct tomorrow, wouldn't create a fossil record similar to dinosaurs, simply because we've been on planet earth for a too short period. https://youtu.be/8xDK2LgSeyk
> What we have to remember is that they existed for over 165 million years, 3300 times longer than modern humans have been around and the number of creatures that lived in that time frame alone, not including very small insect-sized ones must be in the trillions. However, only a tiny number of those would have been in the right conditions to be quickly covered in sediment and then fossilized. Then millions of years later they happen to be exposed on the surface at just the right time before they are eroded away for us to find them. The latest estimate is that the total number of modern humans to have ever existed over the 50,000 years we have been around is about 107 billion. But 50,000 years is a very small slice of geological time and all of our 5000 years of recorded history would be a fraction of that, and the last 200 years or so since the industrial revolution, a tiny fraction of that again, maybe a razor-thin sliver of a darkened layer somewhere in the dozens of kilometers of limestone, siltstone, and shale of the future earth's crust. Depending on where we look, there are gaps covering millions of years in the fossil records, if we were to slip into one of those, we too would be lost in time.
They just have a very different take on some things, because their way of looking at the universe is different from how we look at earth.
Sure, the table has mostly metals but there are a lot of gases.
Maybe metal was not the best word for that, but having word for "all elements except hydrogen and helium" is useful in astronomy
Astronomers presumably mostly think about matter in the form of a star, in which presumably all the hydrogen and helium would be in some sort of plasma state, and perhaps all the “metals” would be too.
I think it would be “absurd” for astronomers to change this because people who aren’t scientists get confused.
The reason astronomers use “metallicity” this way is largely historical: (chemical) metals are not as prevalent in stars as non-metallic elements like carbon and nitrogen, but they are much easier to detect in spectral analysis. So historically the “metallicity” of a star really did refer to the heavy metal content (generally Fe), and considering the physical processes involved it’s not unreasonable to extend this to all non-H/He elements in the star. I think it would be “absurd” for astronomers to change this because people who aren’t scientists get confused.
My bad yo. Please accept my humble apology in not knowing the historical signifacance of something. I'll be doing my masters in 2022/23, biochemistry/microbiology.
I really should have been a bird watcher instead.
Who cares about plant proteins anyway? That's not science at all.
So, really hydrogen, helium, and everything else is a perfectly reasonable classification as everything else acts the same outside of fusion.
At low pressures, it looks like as little as 15 Kelvin is enough to make Neon a gas.
The electronic structure of an element greatly influences its chemical behavior, so elements in the same group tend to be chemically similar. However, hydrogen is a bit of an odd-ball as group 1 elements go.
Jargon will always exist.
Scientists could count Pu244 in these cores to see how many nearby supernovae there were.
(A book recommendation along these lines: Echoes of Life: What Fossil Molecules Reveal about Earth History, by Susan M. Gaines, Geoffrey Eglinton and Jurgen Rullkotter. If you already know a bit of chemistry, it’s a wonderful introduction to the techniques used to analyse rocks in organic geochemistry.)
https://en.wikipedia.org/wiki/Homestake_experiment is perhaps the most-famous, but GALLEX and SAGE use a similar approach.
https://en.wikipedia.org/wiki/SAGE_(Soviet%E2%80%93American_...
The tech behind it is fascinating too.
Radionucleotide contamination is an issue though. Apparently carbon dating will be useless to date anything since the 1950s in the future due to carbon isotope emissions from nuclear testing. So they must have taken care to ensure they were examining clean samples.
Among the primordial element isotopes, a large number are radioactive, including e.g. certain isotopes of the potassium and calcium of our body.
All the radioactive primordial element isotopes have partially decayed since the formation of the Earth, so they can be found now in smaller quantities than in the beginning.
Among the isotopes that can still be found in large quantities, U235 has the smallest half-life and it has decreased about one hundred times.
The next isotopes with the longest half-life, but lower than U235 are plutonium 244 and one isotope of samarium, which have half-time close to one hundred million years.
So these 2 have decreased about 2^45 times. This is a lot so you would not be able to extract a visible quantity of plutonium from a terrestrial rock, but due to the huge number of atoms that existed in the entire Earth, there are still a few atoms of plutonium 244 that have survived from the formation of the Earth.
A few years ago, it was announced that a team succeeded to detect some atoms of primordial plutonium 244 in some rocks, so the primordiality of plutonium can be considered as proven, even if that does not matter from a practical point of view, as there is too little primordial plutonium left, to be useful.
Earth may have been a cooling tank for spent fuel rods used by an alien civilization. Ocean water levels depleted as a result of the cooling process which exposed the land masses. Radiation from the spent rods did radiating things to the surrounding organisms.
IPSO FACTO, we're a result of the super powers bestowed to our watery ancestors.
*edit /fiction ... because some people took this as super serious
As an exercise in creative writing, I think a fun story could be made.
Either that, or the dolphins are done putting up with our shit.
I'm somewhat curious if modern human civilization happened to emerge in the last ~10ky simply because all other time periods since modern humans evolved were too unstable to support civilization.
You mean United Nuclear, which brokers[1] radio isotopes to the general public? https://unitednuclear.com/index.php?main_page=index&cPath=2_... I don't see any Plutonium for sale, but that's not as interesting or useful as Cesium-137 or Polonium-210. They also sell Uranium ore, and do so directly, not brokered, so they have to be careful to vent Radon from their storage room.
[1] IIRC, the Polonium-210 I received was sent directly from Oak Ridge National Laboratory.
EDIT: The sample was actually sent by Spectrum Techniques (https://www.spectrumtechniques.com/). They must be ORNL adjacent or something.
It's not just planes though. Some sailboats have been made with DU keels. Usually lead is used, but DU would presumably allow for a smaller (thinner?) keel.
https://www.theguardian.com/world/2014/jun/19/us-depleted-ur...
And by them, I mean Bob Lazar,.. United Nuclear is his operation. (UFO guy who is likely viewed in a polarized fashion here, I myself am not into the conspiracies)
Now that is fresh. NPR's article fails to tell us how we can tell 'space' Pu from 'test' Pu. It further confounds the issue by calling it 'freshly Made Plutonium From Outer Space' then stating that fresh means 'arrived on Earth within the last 10 million years'. Bad science article.