While our lives are fragile, our numbers few, and our ability to destroy each other great, the capabilities that our technology gives us to survive and spread shouldn't be underestimated.
> For an asteroid to deposit that much energy into the ocean, it would need a mass of at least 1.7 quintillion kilograms. Of all the asteroids in the solar system, only 19 fit the bill. (By way of comparison, the asteroid that finished the dinosaurs was six miles across; an asteroid called Vesta that is one of the potential ocean killers has a diameter of 326 miles.)
A mile of diameter weights 7 * 10^8 * density_of_the_asteroid kilograms.
(mass equals volume of the body * density. Volume of the sphere is 4/3radius^3. Hence 4/3(1/2mile)^3 = 4/3*(1609.344/2)^3 = about 694696971 cubic meters.
The ^3 takes care of that. His answer is for 1 mile, but you can easily substitute 37.23 or whatever miles in the formula. 4/3(x 1609.344/2)^3 = cubic meters.
No, I didn't misread it; the formula he gave was for calculating the mass of a sphere, then he calculated the mass of a sphere with a mile diameter. My point was that was the wrong conclusion to come to for finding a conversion from miles to mass: because each additional mile doesn't add the same amount of mass.
That is, he used the right formula to draw the wrong conclusion. The conclusion, which is what I quoted, is flatly incorrect for each mile beyond the first (and in fact it's only correct for the first mile, exactly, and will be wrong for any other fraction of a mile, if not corrected for using a squared factor of the radius).
But, he is answering a question about a single mile, making it reasonable to actually answer that question. I mean if I say what's a cubic mile of the ocean's mass, I don't want a formula for a cube of arbitrary size I want you know an actual answer.
Not that they are going to actually be perfect spheres, but yada yada.
PS: I accept you really want to feel superior about this, but more often than not people actually know what they are taking about so using the reasonable interpretation is probably correct.
It's not about feeling superior - it's more about correcting people being Wrong on the Internet!
> A mile of diameter weights 7 * 10^8 * density_of_the_asteroid kilograms
This sentence, in so far as it can be understood in English, makes a wrong assertion. Only the first mile of diameter approximates to that; "the" mile, not "a" mile. In the context of the conversation - long lost in this subthread - it's the wrong answer without further clarification. It was in reply to the question "How much does a mile weigh?" - again, note "a", not any specific mile. Someone who takes the reply as an answer to that question would be even more misled, irrespective of how well rimliu understands the problem.
To be really specific: I think 90+% of people would think that an asteroid with a diameter of two miles would weigh 14e8 * density, given this answer - and they'd be wrong, and increasingly wrong the larger and larger an asteroid they're calculating for. Because mathematical intuition is not common.
I added the clarification. Then you came in with your intervention, for reasons that aren't yet clear to me.
'I think 90+% of people would think that an asteroid with a diameter of two miles would weigh 14e8 * density'
If this where YouTube then you might be right, but I would assume the vast majority of people here understand the r^3 part of the formula for a sphere especially when it was included in the same comment. Though they may forget about the 4/3.
And again, it's perfectly valid English to say a mile when you mean exactly 1 mile. AKA "> How much does a mile weigh?" replace that with "How many feet are in a mile." and someone saying 5280 is being reasonable by answering the question.
PS: Now if the original question was per mile then I would agree with you.
> To annihilate tardigrades on Earth we require a mass over ∼1.7E18 kg. The largest observed asteroids in the Solar System are Vesta and Pallas, with masses of 2.7E20 kg and 2.2E20 kg respectively.
That gives you abut 2.7E20kg/326miles ≈ 8.3E17 kg/mile. Funny that WP would give the sizes in miles instead of mass.
Most Americans know roughly how long 326 miles is. Most people don't have any idea how much 2.7E20kg weighs, and changing that to pounds or tons won't help at all.
If you try to make the figure more accessible by comparing it to the weight of some very large object on Earth, most people will still think of it in terms of length rather than weight. For example, 2.7E20kg turns out to be in the same ballpark as the weight of Alaska assuming a continental thickness of 50km and a mean density of 2.7 (granite). But now we're imagining the length of Alaska, which is very misleading because the state is nowhere near spherical.
Assuming these neigh-invulnerable wonders can survive the g-forces, we could mass-manufacture containers to store tardigrades and launch them blindly into space with railguns. The containers would be designed so the g-forces of impact would crack them open.
When the very rare occasion happens where a container impacts a planet or moon, the tardigrades would be exposed to the environment. If it could support the basics of life, after a few thousand years, they would be present enough in the environment that any alien life that exists there or might develop there will eventually notice them.
If the tardigrade DNA contains a message from Earth, it might be discovered and decoded.
It could be the best way to ensure that our existence won't be forgotten in the scale of billions of years.
The message is a chain letter: Your best bet for long term DNA survival is to put all your resources into encoding your civilization into tardigrade DNA and launching it into deep interstellar space, no matter if the effort collapses your civilization.
The problem is that they evolve, and eventually they will lose whatever data we encode into them because it costs resources for them to generate and reproduce it. A random mutation that erases our data would be a slight gain in efficiency.
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[ 3.4 ms ] story [ 91.7 ms ] thread(5 times apocalypse champion)
How much does a mile weigh?
(mass equals volume of the body * density. Volume of the sphere is 4/3radius^3. Hence 4/3(1/2mile)^3 = 4/3*(1609.344/2)^3 = about 694696971 cubic meters.
694696970,906763
> A mile of diameter weights 7 * 10^8 * density_of_the_asteroid kilograms.
You can convert that into a formula aka x mile diameter = x ^ 3 * f(density), but it's just a solution not every solution.
That is, he used the right formula to draw the wrong conclusion. The conclusion, which is what I quoted, is flatly incorrect for each mile beyond the first (and in fact it's only correct for the first mile, exactly, and will be wrong for any other fraction of a mile, if not corrected for using a squared factor of the radius).
Not that they are going to actually be perfect spheres, but yada yada.
PS: I accept you really want to feel superior about this, but more often than not people actually know what they are taking about so using the reasonable interpretation is probably correct.
> A mile of diameter weights 7 * 10^8 * density_of_the_asteroid kilograms
This sentence, in so far as it can be understood in English, makes a wrong assertion. Only the first mile of diameter approximates to that; "the" mile, not "a" mile. In the context of the conversation - long lost in this subthread - it's the wrong answer without further clarification. It was in reply to the question "How much does a mile weigh?" - again, note "a", not any specific mile. Someone who takes the reply as an answer to that question would be even more misled, irrespective of how well rimliu understands the problem.
To be really specific: I think 90+% of people would think that an asteroid with a diameter of two miles would weigh 14e8 * density, given this answer - and they'd be wrong, and increasingly wrong the larger and larger an asteroid they're calculating for. Because mathematical intuition is not common.
I added the clarification. Then you came in with your intervention, for reasons that aren't yet clear to me.
If this where YouTube then you might be right, but I would assume the vast majority of people here understand the r^3 part of the formula for a sphere especially when it was included in the same comment. Though they may forget about the 4/3.
And again, it's perfectly valid English to say a mile when you mean exactly 1 mile. AKA "> How much does a mile weigh?" replace that with "How many feet are in a mile." and someone saying 5280 is being reasonable by answering the question.
PS: Now if the original question was per mile then I would agree with you.
> To annihilate tardigrades on Earth we require a mass over ∼1.7E18 kg. The largest observed asteroids in the Solar System are Vesta and Pallas, with masses of 2.7E20 kg and 2.2E20 kg respectively.
That gives you abut 2.7E20kg/326miles ≈ 8.3E17 kg/mile. Funny that WP would give the sizes in miles instead of mass.
[1] https://www.nature.com/articles/s41598-017-05796-x
If you try to make the figure more accessible by comparing it to the weight of some very large object on Earth, most people will still think of it in terms of length rather than weight. For example, 2.7E20kg turns out to be in the same ballpark as the weight of Alaska assuming a continental thickness of 50km and a mean density of 2.7 (granite). But now we're imagining the length of Alaska, which is very misleading because the state is nowhere near spherical.
It's about the same time as a farthing.
Assuming these neigh-invulnerable wonders can survive the g-forces, we could mass-manufacture containers to store tardigrades and launch them blindly into space with railguns. The containers would be designed so the g-forces of impact would crack them open.
When the very rare occasion happens where a container impacts a planet or moon, the tardigrades would be exposed to the environment. If it could support the basics of life, after a few thousand years, they would be present enough in the environment that any alien life that exists there or might develop there will eventually notice them.
If the tardigrade DNA contains a message from Earth, it might be discovered and decoded.
It could be the best way to ensure that our existence won't be forgotten in the scale of billions of years.
[1] https://www.youtube.com/watch?v=Kh0Y2hVe_bw