The untold story of the world’s biggest nuclear bomb
thebulletin.org
thebulletin.org
(via https://news.ycombinator.com/item?id=29039900, but there's no real thread there)
However, a study from 1963 suggested that, if detonated 28 miles
(45 kilometers) above the surface of the Earth, a 10,000-megaton
weapon could set fires over an area 500 miles (800 kilometers)
in diameter. Which is to say, an area about the size of France.
http://blog.nuclearsecrecy.com/2012/09/12/in-search-of-a-big...
The scientist Edward Teller, according to one account, kept a blackboard in his office at Los Alamos during World War II with a list of hypothetical nuclear weapons on it. The last item on his list was the largest one he could imagine. The method of “delivery” — weapon-designer jargon for how you get your bomb from here to there, the target — was listed as “Backyard.” As the scientist who related this anecdote explained, “since that particular design would probably kill everyone on Earth, there was no use carting it anywhere.”
The 10GT weapon really would have been BACKYARD. At 6MT/tonne (the upper bound for thermonuclear weapons) it would have weighed 1667 tonnes.
Life tends to not want to die. And somehow they seem to survive enormous catastrophes against all odds. The dinosaur killing asteroid was ~100 million times more powerful than the Tsar Bomba. Yet we're here.
The bigger threat is from the firestorms that throw so much soot into the atmosphere that it's ruined for our kind of life. But that probably still wouldn't get rid of life on Earth.
It's radically different surviving in a hostile environment (limited sun, cold weather, limited food) than one that will literally kill you by interacting with it.
The article is a brilliant piece of writing, but scattered through it, you can gather the bits and pieces of math that would describe why it's not strategically practical.
- Bomb weight / size scales roughly linearly with bomb yield. How are you going to get that massive bomb over to France? The aircraft required to haul it over would be exceptionally vulnerable. If you want to use a rocket, you'd need something on the order of the Apollo Saturn-V rocket to lob it over (especially for 1960's technology), and that rocket would as well would be vulnerable on the launch pad. Good luck hiding it while you fuel it up. Defending nuclear weapons (cough silos / subs cough) was/is no small task.
- The troposphere (which accounts for the main density of the atmosphere) is only about 13 miles in height, on average. It's thinner near the poles and thicker near the equator. But anyhow, past a certain yield, you literally really do blow a hole in the atmosphere. At that point, the atmosphere acts like a tamper, channelling much of the additional yield into outer space.
To which end, Sakharov was right. The big bombs were massive publicity stunts, and to the degree that the Soviet leadership pursued them, they were wasting money on propaganda projects.
Optimistically, military planners are aware of this, and are just doing pork barrel spending.
Pessimistically, military planners don't care about this, and are actively working on 'winning' a nuclear war.
Even if you make those simplifications though: If your choices are pre-emptive strike where MAD applies now (near-total destruction) vs. live to 3 months from now, where you have a post-MAD world where one adversary dominates, the post-MAD dominant adversary no longer has the incentive to pre-emptively strike since they aren't worried about a pre-emptive strike from their adversaries since they'd have an effective missile defense system.
Striking today means MAD happens and your country gets wasted. That only makes sense if the shield-building adversary is some sort of psychopath who wants to see you dead.
The 3 big nuclear powers don't seem to be that stupid. Maybe the calculus would be different with Israel vs Iran or India vs Pakistan, where the conflict has religious aspects.
Or if they may become a psychopath who wants to see you dead - in the name of self-defense, of course. Or if they think that you are a psychopath who wants to see them dead. Or if they think you may become a psychopath who wants to see them dead.
It's difficult to assure your counterparty that you will never behave in a psychotic manner in the future - or to assure yourself that they will not.
If you're not planning on starting a nuclear war, and you assume that your adversary isn't going to, either, why do you need a missile shield, anyways? MAD is a necessary and sufficient deterrent. If you're building a shield, you are very conspicuously betting that at least one of these two assumptions is no longer true...
These assumptions better be strongly supported by evidence, if one's going to decide to get their country annihilated by attempting a first strike.
Striking first won't protect the country from a hypothetical future attack, it will just make it happen now. I don't really see a sane reason to do it if the threat isn't considered immediate.
U.S. Nuclear Weapons: The Secret History is sadly missing from LibGen, but it appears to be available as a digital checkout from the Internet Archive. It's a good companion book to Swords because it went through a professional editing-publishing cycle. Swords is a lot longer and rawer, with a higher ratio of text to illustrations.
1) Square-cube law. You do more damage with a collection of smaller warheads than with one big one with the same total yield.
2) The Earth isn't flat. Once a boom gets big enough the area of damage doesn't go up much as the shockwave ends up separating from the ground and the atmosphere above the bomb just ends up blasted off. Note that this does *not* limit the usefulness of big bombs detonated high up for thermal and EMP effects. Very big booms in low orbit could be very nasty with total surprise.
Obviously there's no need for them on Earth or anywhere nearby.
But it might become useful to scale nuclear explosions to an arbitrary extent if/when something large on a collision course with Earth is discovered.
In particular, although these dispersion methods (as you pointed out) don't typically reduce the impact energy to zero, they offer a roughly 2 order-of-magnitude decrease in impact energy while requiring only month-scale warning.
In contrast, diversion techniques which can reduce the impact energy to 0 (e.g. by shifting the impactor to 'miss' our planet) can require decade-scale to accomplish their goal.
[0]: https://www.sciencedirect.com/science/article/pii/S009457652...
It was from a reply to a question I'd asked recently here on HN that an eyewitness to the Chelyabinsk impactor reported on the heat of that event. Even as the impactor largely broke apart and vaporised 20--40km above the Earth, it shed a huge amount of heat over a large area. Not enough to be lethal, but enough to be felt.
A larger mass would deliver correspondingly more energy. And energy is conserved.
Correct, much of the atmosphere would become superheated, perhaps to plasma, and radiate the energy away non-directionally. So only half would radiate toward the surface -- not that that's a whole lot of help.
For a sufficiently large single impactor ... there's also an ejecta cloud, and for sufficient sizes (e.g., Chixulub+), that also results in atmospheric warming by a similar mechanism, though from secondary rather than primary fireballs. Several descriptions of the K-T mass extinction go into this mechanism in detail. Even at the antipodes, most exposed terrestrial life would have been subjected to at the very least uncomfortable, and probably lethal, heat.
I've had the experience of feeling radiated heat from a bushfire (and a relatively small one at that), and even at 100s of meters distance, it could be distinctly felt, with the sense that this wasn't just a nearby small heat source (a radiator or firepit), but a large conflagration. The prospect of a wall of flame sweeping down a hillside, or of a sky on fire, is slightly more real to me since that.
Area of impact for original rock: 78.5 km2 Area of impact for a 1000-km dust cloud: 785,398 km2
Asteroids that struck 65 million years ago had 3×10 ^23 joules In case of dusk cloud, that's 382,000 Megajoules per square meter impacted
A column of air with a cross-sectional area of 1 square centimetre (cm2 has a mass of about 1.03 kilogram A square meter of air column weighs ~10 tons Heat capacity of air is 1.0035 joules per gram per degree centigrade So it's 10 MJ to heat up 1 m^2 of atmosphere by 1 degree
So if all the energy was absorbed, converted to heat, and evenly distributed vertically (unrealistically), it the atmosphere would heat to 38,000 degrees. If this is in the right ballpark, then radiation will dominate this equation, which I can't estimate. Upper atmosphere will be heated to a glow, and will radiate away most of this energy. Whatever happens, not a happy scenario.
For a dust cloud 5,000 km in diameter, situation is quite different: 3,821 megajoules per square meter, that's 382 degrees rise per square meter. For comparison, the Sun provides 115 Mj/m2 per day.
I would anticipate that in case of 5000 KM dust cloud there wouldn't be a major loss of life - the atmosphere doesn't conduct heat very well, so most of it would be stuck in upper atmosphere and radiated away. I think a realistic 'space dust cloud' would disperse very quickly to greater than earth radius, but it's not going to be uniform dust.
The initial pulverisation would presumably result in a distribution of velocities amongst particles. Some of those would achieve escape velocity and leave the cloud. Some would not.
Time to re-coalesce would depend on the total cloud mass and maximum extant itself. In total, it would be relatively quickly.
The resulting re-agglomerated impactor would then resemble a rubble-pile or the World's Largest Dust Bunny. It would be significantly disrupted by both tidal forces and interactions with the atmosphere, though of course, how greatly it is disrupted by atmospheric friction would again be a function of mass.
But the point remains: under the influence of the cloud's own gravity a cloud of merely separated particles will re-coalesce. You can look up in the night sky much of the time to see an example of this yourself, the Earth's moon.
And again, depending on the mechanism, a fair fraction of particles, quite possibly / probably the majority, will approach the original centroid of the mass.
In practice, pulverising planets and/or planetoids is likely a challenging proposition. Early experimentation on animal models tends to support this hypothesis:
Though the point remains that what you've got to do is avoid impacting the asteroid entirely, whether it's a single solid core or a dispersed dust-cloud. Or more precisely, the total delivered energy has to be considered and kept to a survivable maximum.
That said, I'm now wondering what it would look like to suddenly have a sub-lethal dust-cloud impact Earth. I imagine there'd be an initial few stray shooting stars, then a rapidly-growing glow as the dust struck the atmosphere. Hrm...
I am in favor of numbers in a discussion like this, even if wrong, (and I am not a physicist) they're more interesting than without.
- The asteroids considered a threat to the Earth start at about 460 feet in diameter. This is about an order of magnitude less (in diameter, not mass) than the impact that got the dinosaurs but would still probably be a lot worse than anything in recorded history, if it hit land or sea. It's said to be about a 10,000 year level.
- Density is uncertain, but I found a figure of 2.7 g / cm^3 as a mid range.
- This equates to 3.9 million metric tons or more being probably what we would want to do something about.
- Freeman Dyson wrote a paper in 1968 or so, about nuclear pulse rocket design, that described a hypothetical spacecraft that would mass forty million metric tons.
- It would, however, accelerate very slowly; at 0.00003 g (supposedly).
- But that's really not so slow.
- Ignoring orbital mechanics, because I just can't right now, if something is headed for Earth, it should be enough to move it by one radius in some direction...right?
- Earth is something like 7926 miles in diameter, and 6.4 megameters is ~half that.
- d = 1/2at^2, 1/2a = 0.000147 m/s^2, so divide the radius by 0.000147, take the square root, and I get ~209,000 seconds.
- That is...2.4 days!
- However, it presumes a one megaton bomb going off every 100 seconds, for a total of around 2,100.
- That sounds like a lot. On the other hand, it's less than 3% of the nuclear bombs the US has produced since 1945.
- However they would have to be custom designed, is my impression, as "nuclear shaped charges" and not just recycled warheads.
- The asteroid might have to be reinforced on the size that was being pushed. The spacecraft design included a 1mm thick sheet of copper to absorb thermal energy.
- However, if the asteroid was four and not forty million tonnes, then less time and fewer explosions would be needed, I would assume. Would it be ten times less? I'm leaving that as an exercise for the reader.
https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propuls...
https://en.wikipedia.org/wiki/Nuclear_weapons_of_the_United_...
Moving an asteroid is a lot more plausible than you'd think, but it would require "normal" sized bombs, not super gigantic ones.
Here in Blighty, during the early cold war we built fall-out shelters and equipped a civilian force with "Green Goddess" fire engines to enable them to extinguish fires from nuclear flash.
Yet this all stopped after development and adoption of the Hydrogen Bomb..... because unlike nuclear weapons (kT yield), trying to defend against thermonuclear weapons (MT yield) is pointless. This was a very real and honest defence policy.
https://en.wikipedia.org/wiki/Green_Goddess
[In the UK, some younger people may recognise the Green Goddess Fire engine because they were seen during fireman strikes].
"Duck and cover" won't work if you're too close to the fireball, but most people won't be.
For some reason makes me think of the Demon Core accident(s), from the early days of bomb development:
The other thing I come away from this thinking is that our bodies are way better at dealing with damage from radiation than we give them credit for.
Then again you got girls using Radium as makeup [0], so who knows what way they'd find to screw up. (I'm aware they didn't know the Radium was dangerous and am mostly joking.)
Depictions of the Tsar Bomba usually focus on the huge mushroom cloud, which is awesome (in the original "causing awe or terror" meaning of the word). However, I think the geometric simplicity of the fireball is even more effective at inspiring awe.
For a brief moment, the sky was filled with the light of a human-made star.
https://en.wikipedia.org/wiki/Status-6_Oceanic_Multipurpose_...
I read about Poseidon a few weeks after it first became public, so it's been a bit now.
Do we happen to have any indication as to whether or not the US military/DoD is internally at all seriously scared/concerned about it?
I've been anecdotally told by a very old DoD engineer who was somewhat familiar with things - that when the soviets first came out with their heavily armored multi-hull submarines, there was actually great concern about the fact we didn't at the time have technology to ensure two torpedos could near simultaneously hit within the required radius to pierce all the way through.
A lot of engineering hours went into making the targeting systems of the torpedos capable of doing so. Or maybe he was full of shit, who knows.
It just seems like Poseidon is quite the threat, but we haven't heard too much concern about it yet.
That bomb was finally measured to be 'only' 20 kilotons. [1]
God I hope one of these is never dropped in anger.
1. https://www.osti.gov/opennet/manhattan-project-history/Event...
I think what got Japan to surrender was a certain common sense in the emperor and some of the elite that a final last stand wouldn't do them much good. Especially not with the Soviets joining in.
So no, I don't think just detonating the bombs "harmlessly" would have have had the same effect. In fact hitting a target just slightly off the mark(like Tokyo Bay) would have been presented as American incompetence and failure of aiming.
At this point where anything bigger creates a threat that goes beyond nations, what kind of person even proposes this. "This is child's play, there's much more effective ways to destroy the planet"
I had no idea Chicxulub was that big.
(I live in the vicinity of the Cascadia subduction zone, which will probably experience something similar some time in the next couple hundred years.)
You need an MIT account, though. Would anyone with one care to summarize?
https://scholar.google.com/scholar?q=J+Grams+-+Journal+of+Co...
This seems to be the actual article.
Yes, later on in his life he actually saw what he'd been. It seemed to have transformed his life. [https://history.aip.org/exhibits/sakharov/intellectual-evolu...] I don't accept that as an excuse for what he was willing to be part of.
Later on, he said, 'In 1948, ... no one asked whether or not I wanted to take part in such work. I had no real choice in the matter..."
Yes, he did.
But certainly it would be much better to just have a few dozen nuclear weapons per country to stop WWII like events than the thousands that the US and Russia still have that might cause a serious nuclear winter event killing most of the people on Earth.
From your link Sakharov had similar musings: “Have Soviet and American atomic scientists helped to keep the peace? After more than forty years, we have had no third world war, and the balance of nuclear terror... may have helped to prevent one. But I am not at all sure of this; back then, in those long-gone years, the question didn’t even arise. What most troubles me now is the instability of the balance, the extreme peril of the current situation, the appalling waste of the arms race... Each of us has a responsibility to think about this in global terms, with tolerance, trust, and candor, free from ideological dogmatism, parochial interests, or national egotism.”
This site's cookie warning says: Please indicate your consent to our tracking tools and the sharing of this information by selecting “I Consent” or by continuing to browse this website.
The "continuing to browse this website" seems shady. Can someone explain how this is even supposed to work? Is there a timer that expires? If I scroll at all am I opted in?
Also, is this even legal in jurisdictions that require a cookie opt-out? I thought I read some language about required a positive user interaction to accept tracking.
1. open browser
2. navigate to website
3. website installs cookies
4. you must have already consented!
You don't want the interest of 445 million people, most of whom will consent to tracking? OK with me.
https://www.theverge.com/2016/7/20/12243592/kickass-torrents...
That's why there are so many shitty american middle-of-nowhere Daily Star Gazettes that block EU visitors with a laughable "our EU visitors are important for us". It seems that they agree with GDPR that it covers them if they serve anything to EU citizens.
I would be surprised if it "works", or if they do anything other than tracking you from the first moment until you opt out.
Area scales as square of radius, so (assuming the radius calculations are right, the ratios are approx cube root of 10 which is napkin-level correct) more than 4x as much area is effected (incinerated).
Doesn't change much about the political/historical issues, but you would fail high school math for this.
Yes, but they’re referring to volume - which does scale as a “cube”. Bombs detonate in 3D, not 2D - moreso when aerial/aquatic.
> but you would fail high school math for this
This seems quite vitriolic and uncalled for.
>This seems quite vitriolic and uncalled for.
I apologize if this sounded too harsh, but "The Bulletin of Atomic Scientists" should not make basic errors like this. It was a very interesting historical article, but when you miss stuff like this, which is simple to catch, I wonder about the journalistic fact checking, which is considerably harder.
It's a silly error which in no way undercuts anything in the article afaict, but it annoys because it is very simple and obviously true by unit analysis. I make silly errors too, as we all do, present company excepted. But it does undercut my confidence in the more far difficult journalistic work being done, which I cannot interrogate with my limited mathematical skills and pretty much have to take on faith. To me it speaks to the question of whether I "learned something" or "read some words".
This is a very boring digression and I take full responsibility for making a ticky-tacky point, which I have now I believe fully explained and contextualized.
You could think about what would happen in space (a spherical explosion), then consider what would happen as it got closer to the earth.
>EMT = Y[^]2/3 where Y is in megatons.
>This relation arises from the fact that the destructive power of a bomb does not vary linearly with the yield. The volume the weapon's energy spreads into varies as the cube of the distance, but the destroyed area varies at the square of the distance.
Src: https://www.atomicarchive.com/science/effects/energy.html
It's just geometry, or dimensionality, you cannot directly compare 1D and 2D quantities. Type mismatches are often bad in programming, but always fatal in physics.
Similarly underwater explosions caused spherical and columnar affects depending on yield and depth.
That's a thought about killing an entire planet by burning it's atmosphere. Cliche thing but "burning hole in atmosphere". Reminds me like ants on a rock.