I seem to recall that in my childhood (1980s, Canadian elementary schools) it was still treated as only one of several competing explanations, but now it’s pretty much an accepted fact.
Which makes sense given all the evidence, but I still have this odd sensation making me feel like I missed the memo! Am I the only one who feels this way?
So I guess it was indeed proposed around the time I was born and “proven” by the time I had outgrown dinosaurs as an interest/hobby...
I wish we could unite and start forming a plan to survive the next one. I wonder what that would entail?
See: https://en.m.wikipedia.org/wiki/Asteroid_impact_avoidance
Being an interstellar object though, it moves faster than the escape velocity to the sun, so it would pack a higher energy per unit of mass than a regular comet or asteroid. Fortunately such objects are also somewhat rare.
Couldn't we detect such things with radar? Given the right frequencies, rocks and dirt will reflect - that's how terrain-following radar works.
So yes, I think we could, but there are some significant problems.
1. 1/r^2 power loss, in both directions. We would need a massive radiator, and very sensitive detectors.
2. The detectors are in the wrong place. You send out your signal, and several hours later the response comes back, by which time the earth has rotated. So where your detector has to be depends on the distance to the object, but you don't know the distance to the object!
So we'd need a bunch of detectors at various points around the globe. And we'd need a huge power source.
Which brings me to solar flares. They emit radio waves. Do they emit enough power at the right frequencies to be useful for this?
Even nukes have a surprisingly small effect, unless they are buried. We have landed on on an asteroid, but have yet to embed a nuke in one.
The trick about nukes is you have the risk of just making an harder to stop by making a cloud, like say comet levy which turned into 21 pieces, but delivered the same total energy when hitting the atmosphere.
The nice thing about the paint is that it's not that hard, even asteroids have gravity, and we have orbited (very slowly) asteroids before. It doesn't cause the astroid (which might just be a loose collection of rocks) to break up, and you get a huge win per pound of delivered mass, granted it takes months or years to accumulate into a large orbital change.
However there would be more surface area to burn up in the atmosphere, and if you do it far enough out and I'd think it would require very little nudging to move pieces out of the way
Generally if it's a planet killer you want to take no chances. The earlier the detection the better, and changing the albedo will work if it's a sand up to a solid rock.
I've heard similar proposals with a "gravity tug", but it's not clear to me that it would work with a significantly larger change in velocity than just using the fuel directly. Keep in mind that the asteroid that killed the dinosaurs was approximately 10km (some sources) to 15km (other sources) across, and we have no reason to think that future asteroids might not be bigger.
The largest atomic crater I could find was from a 104 kiloton bomb that created a 400m wide and 100M deep. Both the USA and Russia has similar tests, and that would be just a small dent in a 15km across asteroid. Both were from 100-200m deep explosion, and it's not clear if deeper would necessarily be better. Sure you might crack a 15km long asteroid into two pieces, but it wouldn't help much. Vaporizing a 15km asteroid is going to take WAY more than 100 kiloton.
What might work is some kind of nuclear engine that melts stone/sand/ice and ejects it at high velocity, working it's way into the center of the asteroid. It would need a throttle to only fire when it helps and idles when it doesn't.
We've actually got a fairly decent handle on asteroid protection right now with the cataloging work that's been done in the last couple of decades. Comet impacts, supervolcanos, and possibly a nuclear winter are really the biggest threats of this sort
In the impulsive category, the use of a nuclear device was found to be the most effective means to deflect a PHO [Potentially Hazardous Object]. Because of the large amount of energy delivered, nuclear devices would require the least amount of detailed information about the threatening object, reducing the need for detailed characterization. While detonation of a nuclear device on or below the surface of a threatening object was found to be 10-100 times more efficient than detonating a nuclear device above the surface, the standoff detonation would be less likely to fragment the target. A nuclear standoff mission could be designed knowing only the orbit and approximate mass of the threat, and missions could be carried out incrementally to reach the required amount of deflection.
[0]https://www.nasa.gov/pdf/171331main_NEO_report_march07.pdf
Neil deGrasse Tyson has made many similar comments, one quote “Dinosaurs are extinct today because they lacked opposable thumbs and the brainpower to build a space program.”
https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_e...
I think was around when consensus shifted from "Yeah this is probably what happened" to "This is it"
Found it!
https://www.theatlantic.com/magazine/archive/2018/09/dinosau...
That said, if you look at the patterns of extinction, survivors seem limited to things that could hide in burrows or in deep water and then survive for an extended period exclusively on scavenging, as if everything that happened to be on the surface was suddenly killed and then photosynthesis stopped working for a few years. Notably, species that would normally be very sensitive to climate change like small amphibians survive whereas generalists capable of long distance migration die out. There may have been ecological stress beforehand but a singular cataclysmic event turned it into a mass extinction.
Do we know for sure that the volcanism in the Deccan traps wasn't caused/triggered by the asteroid impact? I know they're pretty much located at the opposite ends of the world, so could the shockwaves from the initial impact have created an amplified node at the other side?
(edit: wikipedia[0] says it's inconclusive:
> Although the Deccan Traps began erupting well before the impact, [..] the impact may have caused an increase in permeability that allowed magma to reach the surface and produced the most voluminous flows, accounting for around 70% of the volume
[0] https://en.wikipedia.org/wiki/Deccan_traps#Chicxulub_crater )
The Great Dying you speak of happened to coincide with an asteroid crater off the coast of Antarctica [0]. I haven't been able to find an accurate globe of the continents at that time ([1] doesn't show the poles in great detail), but it does look like eastern Siberia was at the antipode of the Australia/Antarctica boundary. So the theory seems to hold up -- at least from the confines of my armchair, that is.
[0] https://www.universetoday.com/8221/huge-asteroid-crater-in-a...
[1] https://resize.hswstatic.com/w_907/gif/cretaceous-map.jpg
Case in point, a pandemic could have wiped out all the dinosaurs 1 million years before the asteroid hit and we would have no fossil evidence of that.
The asteroid theory is still just a theory and for anyone to be arrogant enough to say that it is fact doesn’t deserve to teach science in any capacity.
https://en.wikipedia.org/wiki/Extinction_event#Other_hypothe...
There are potentially dozens of conceivable events that could have caused extinction level events and taking a single theory and selling it as fact is wrong.
We should be teaching it as a theory with pretty decent evidence but not much more than that because it’s impossible to say what really happened. Anything more than “this is a plausible idea with some pretty good evidence behind it” is science fiction, not science.
Your previous comment included questionable phrases such as "any degree of certainty", "absurd", "just a theory".
To think we can come to any conclusion with the tiny amounts of evidence that remains or to clue together all the remaining bits and pieces of residual evidence is extremely arrogant.
It makes for a decent story and hypothesis, and it sounds plausible. But to teach people that this is basically fact is absurd, which is my point. It should be taught as a theory.
Much of the research into geology has been funded by the oil industry, who are enormously interested in knowing these kinds of processes, in the hopes it will help them locate it.
The evidences that remains after 70 million years is orders of magnitude less than the evidence that has been destroyed over the last 70 million years.
To take the morsels of evidence we have and think that paints a definitive answer is the height of human arrogance.
Everything we are told or taught is a simplification, or a model.
The distinction between "fact" and "theory" is not always as clear as you imply.
The ability to doubt a proposition while simultaneously believing that it may indeed be true is a core psychological skill for any scientist. We ought not treat every theory that we believe to be true as "fact."
It creates massive groupthink and stifles discussion on the topic which is worse, because it becomes politicized especially in this day and age.
Some theories, ranked by the strength of their supporting evidence, e.g. and IMO:
0 Baby-eating lizard aliens run the US government
1 ..
2 String theory
3 ..
4 ..
5 ..
6 ..
7 Asteroid extinction event
8 Relativity
9 Evolution
So we'd need a new word, that means "very well-supported theory, based on all available evidence, with no strong competing explanations". Open to suggestions here!
But for non-specialists, at what score is it reasonable to treat a theory as "fact"? I'll vote for 7.5. :)
Obligatory: Colloquially, "fact" as "true idea" -- not "quantum of isolated information which can be knowable". The latter definition is lovely, but has little application in the world of people.
Regardless I’ll say the same thing I tell my kid which is the same as what you said. Everything that isn’t a fact is a theory with various levels of evidence. The stronger the evidence, the more likely the theory is correct. But a theory will weak evidence could suddenly improve if a new piece of strong evidence comes to light. And a strong theory could become weak if a piece of evidence disproves the entire thing. So keep an open mind and don’t mistake theories for facts.
Fair point. It was crowded up there, and my physics is less than current.
I think we agree, really. I'm just not as strict on the semantics of the word "fact".
I agree that laziness on the margins of fact is lazy, esp for specialists. I don't think we can authoritatively say that anything is an absolute truth. But there are some really useful models.
The extinction event model serves a purpose for paleontologists, and it's pretty good for most of them. It serves a different purpose for non-specialists.
There are few facts, only conjectures that your sensorium fails to reject to various degrees. We then overload 'fact' to mean more things than logical truisms constructed from axioms and to extend to conjectures that we have collectively failed to reject despite strong attempts.
The asteroid extinction hypothesis is fact in this (mainstream) terminology.
> In the deposit, the team discovered an ancient freshwater pond whose occupants had been quickly cemented together by waves of sediment and debris. The fossils include sturgeon and six-foot-long paddlefish, their scales intact but their bodies ripped and smashed; marine mollusks; leaves and tree fronds, and the burned trunks of trees. The fish carcasses were not bloated, decayed, or scavenged, suggesting that they were buried quickly — and that few animals were left alive after the cataclysm to come digging.
> The fossil deposit also teems with tektites, tiny glass beads that are the telltale fallout of planetary-scale impacts. Fifty percent of the fossilized fish were found with tektites in their gills, as if the fish had inhaled the material. Also recovered were tektites trapped in amber. Their chemical composition was unchanged in 66 million years, and it closely matched the unique chemical signature of other tektites associated with the Chicxulub event.
[1] https://www.nytimes.com/2019/03/29/science/dinosaurs-extinct...