I love this type of articles where we can reconstruct what happened so long ago just based on careful observations.
Some other instances I've come across:
* The K-Pg extinction event that wiped off dinosaurs had the impact it did because the asteroid happened to impact a shallow water region. This kicked up a lot of sulfur (in gypsum) that further affected global climate: https://en.wikipedia.org/wiki/Chicxulub_crater#Effects
* Earth likely had rings ~466M years ago. We deduced this by looking at impact craters from that time period, and seeing that they all lie near the equator (accounting for continental drift): https://www.sciencedirect.com/science/article/pii/S0012821X2...
* Earth's rotation period was probably frozen at 21h, ~600M years ago, likely due to interaction between lunar and solar tides. This resonance could have been broken by ice ages (!!!). Amazing to think that global climate affects earth's rotation: https://en.wikipedia.org/wiki/Earth%27s_rotation#Resonant_st...
> reconstruct what happened so long ago just based on careful observations.
Me too! My book is filled with them. Like how minerals in lava, affected by Earth's magnetic field, lock into place while cooling, which provides us with yet another cross-check for radiometric dating. See page 23:
To the best of my knowledge not everyone agrees to that hypothesis. One of the strongest arguments against it is that paleontological evidence is always incomplete. Holes in it that are treated in favor of the hypothesis are actually smaller or comparable to holes that appear just due to incompleteness.
Read the article. That's the subplot. We get to see just how non-scientific science really is. The true and current evidence points to an asteroid being the final blow to an already declining environment. But the status quo narrative so strong that egos and biases override facts.
The dinosaurs were not “wiped off”, by which I mean they are not extinct. This is an extremely widespread misconception that popular science articles like this one keep perpetuating. We should do better and help people understand that (some) dinosaurs survived and evolved into modern birds. Birds are dinosaurs. Dinosaurs are alive today.
I get that, but most people don't know that birds evolved from dinosaurs that survived the asteroid (which I think is both interesting and important to know) and I think it's the responsibility of science communicators to... communicate that.
If PETM was due to large scale use of hydrocarbons, there should be evidence of depletion in the strata, right? For example, currently not all sources are uniformly exploited -- some coal seams and oilfields are all but depleted, others are currently being extracted, and others are yet to be found/exploited.
We should have seen signs of similar non-uniform usage in the strata from before that time period. I wonder if any research has been done on this.
> If PETM was due to large scale use of hydrocarbons, there should be evidence of depletion in the strata, right?
And all the byproducts of this use. We are leaving abundant traces of our existence basically everywhere. We can see it in the ground, in the seas, in the ice caps. Our existence will be very obvious to anything caring to just dig for quite a long time.
The content of the atmosphere gets washed out by rainfall and does end up in the sedimentary record. Similarly, we can follow the oceans’ acidity from sediments. Large chemical changes would also show up in isotope ratios.
The ice caps are only about 30 million years old, and the land and oceans are similarly transformed over long time scales. The only techno signature I'm aware of that would be clearly detectable 50 million years after our civilization is gone is reinforced concrete, which should produce a worldwide layer of a limestone-like mineral with iron inclusions that would be both unique in the geologic record and difficult to explain by any natural process. If a civilization did not use reinforced concrete nor some other such material that would leave a similar signature, it would be quite difficult to detect at that timescale.
We get bones and feathers from animals living 10 million years before that. We can find the traces from the Chicxulub impact across the whole world. Same for large volcanic eruptions. Burning enough stuff to cause this kind of global warming would leave plenty of chemical traces. It’s just not serious.
I'm not sure if that's a safe assumption. Do we know what the sources we are exploiting right now are going to look like in tens of millions of years? Our models of the evolution of hydrocarbon reserves are based on those we've found, and we simply assume the differences between different deposits are natural in origin. It's easily possible that places where we didn't find hydrocarbons did in fact have them at a previous point in time, or that there was more in a given reserve in the past.
> How many of them have liquid water without being super saturated with salts? What is the level of confidence we have?
We don't know the composition yet, just that a salty ocean supports the evidence we've seen. For example, Europa interacts with Jupiter's magnetic field in such a way that makes sense only if there is a large amount of electrically conducive material inside Europa. Given what we know about its formation, metallic stuff is unlikely. A salty subsurface ocean is a more suitable explanation. We'll know once Europa Clipper gets there (one of its missions is to 'taste' the ocean by flying past really close).
There are other reasons to suspect a subsurface ocean, such as signs of a geologically active body (like Enceladus), which in turn implies there is enough heat inside to have an ocean.
> Which are most likely to bear life given our current hypotheses around the origins of life?
Europa, maybe Enceladus. Note that our search for life is heavily guided (biased?) by our understanding of how we think life started here on Earth.
Specifically, we needed these ingredients (non-exhaustive):
* a liquid medium to act as shelter and transport medium (liquid water ocean)
* a source of energy, something that life can 'eat' (hydrothermal vents in the beginning, sunlight later)
* protection from space-borne threats (atmosphere, magnetic field)
* a home that isn't geologically dead (like the Moon, or Mercury), but also isn't too active (like Io)
Europa checks most of the requirements:
* suspected subsurface ocean
* geologically active. This is important because Europa and other moons are too far away for sunlight to be a big source of energy. There has to be another source. Radiogenic heating (released by radioactive isotopes) and primordial heating (left over from its formation) aren't enough for moons to sustain liquid water (especially 4.5 B years after formation). This means tidal flexing is what we should be looking for -- something we know Europa has.
* Europa's thick icy crust blocks pretty much all radiation. Barring a thick atmosphere (which only Titan has), a subsurface ocean underneath an icy crust is the best life can hope for out there, for protection against radiation.
* We don't know much about what goes on underneath the surface. If the bottom of the ocean contains geothermal vents, then that could harbor earth-like life.
Saturn's moon Enceladus checks many of these same boxes (tidal heating, abundant water, signs of a young surface indicative of geological activity).
JUICE and Europa Clipper missions should fill in many of these gaps, and help confirm our understanding.
The wikipedia entry about oceanography may be outdated on Ceres, at least from my watching episode 2 of the 2024 BBC Solar System series. The NASA Dawn probe found the salt there is very short lived in vacuum so it has to be continually replenished so from that it is hypothesized there must be a salt water ocean underneath the surface which sounds more definitive. The wikipedia entry references a 2005 paper and 2007 paper, and the Dawn probe did the Ceres survey in 2015.
Largest ocean in our solar system isn't even on Earth, apparently:
> ... Ganymede’s ocean is even bigger than Europa’s—and might be the largest in the entire solar system. “The Ganymede ocean is believed to contain more water than the Europan one,” he says. “Six times more water in Ganymede’s ocean than in Earth's ocean, and three times more than Europa.”
The largest ocean in the solar system actually is on Jupiter [1]. The gas planet has an absolute massive amount of liquid hydrogen on its "surface". But yeah, liquid hydrogen isn't water, so it might be the biggest ocean, but not the biggest ocean made out of water in our solar system :).
It would make Mars warmer. It would melt all the ice and CO2. It would give Mars an ocean. Of liquid rock. This is assuming that it doesn't destroy Mars completely. There might be enough fragments to make Solar System dangerous place and destroy life on Earth.
Europa is the size of our Moon. Colliding it with Mars would be similar to the collision that formed our Moon.
At some point I saw a design for a machine you could park at the Lagrange point between Mars and the Sun that would collect solar power and spit out a magnetic field strong enough to deflect enough of the solar winds that we wouldn't need to worry about that.
If we had the technology allowing us to move a full satellite through the solar system, we could probably do it in a way that would just make Mars a bit closer to the sun so that the weather gets nicer (sure, if it gets too close to earth it's going to mess up with both orbits, but we can as well correct it when it happens, right?)
It doesn't have to be near the sun to have heat or be warmed by the Sun. It is still currently in the goldilocks zone, same with Venus. The difference is how well each planet traps heat. No atmosphere no heat for mars, highest peak surface temperature is 70 fehrenheit or 20 celsius. Not much but enough green house gas and you could raise it by 20 degrees or more. Other thing to consider is that you don't need to move Mars, you could create artificial magnetospheres.
Absolutely. Imagine you are saving a text file to NAS with a super-secret password to your Bitcoin wallet, for example "password". While it was in memory before it reached disk, one bit was flipped and the file contents became "pastword" which OS happily saved on your RAID. And now you've lost your Bitcoins forever.
Consider all the RAM along a network transmission. Maybe you’re using authenticated encryption, maybe your transfer has an internal or out of band checksum. Maybe not.
These AI assistants (Rabbit R1, Humane AI Pin), as they exist now, probably can be replaced by apps. However, if you give them the benefit of the doubt and think about what they're supposed to be (or eventually will be), owning the platform is a must.
An example: Google/Apple doesn't allow third-party apps access to call audio. So you couldn't implement live translation/transcription, by just being an app.
Google/Apple will jealously guard their turf in their ecosystems (to make space for their own AI assistants probably), so this level of third-party access is unlikely to be forthcoming.
I agree as someone who's wanted to develop an iOS app for years but can't get over the App Store monopoly risk.
But, from a business sense, doesn't it seem like they're doing it backwards? Why not make a best-in-class AI assistant app, build a big userbase, and take the money to research hardware and harass Apple concurrently? Why start with hardware first?
