A Gigajoule of Damage

[Fred Brackin]

Originally Posted by johndallman

15-20 kilotons. That seems to be the natural yield of the types that were easiest to build with 1940s technology.

What size would sir like?

As an example, the Trident II submarine-launched ballistic missile can carry 8 475kT warheads, s.

To add a little detail that was 15 kt for the U-235 device at Hiroshima and 22 for the Plutonium-239 bomb used at Nagasaki. Most modern warheads begin with the Pu-239 type.

That is before you get into the "fission-fusion-fission" thing. There's a rule of thumb that yield doubles for each stage you add. Fission needs neutrons to start and you have to use elements that ae natural sources of neutrons. Fission also puts out 94% of its energy as heat and only 2.4% as more neutrons. De-T fusion needs heat to initiate but puts out 80% of its' yield as neutrons. Using these two things in alternation is a textbook definition of "synergy".

You begin by boosting the Pu-239 stage by adding deuterium and tritium gas to its' hollow core before detonation. These gasses fuse as a result of first stage fission and make lots of neutrons which fuels more fission and so on. Allegedly the Russian name for such devices is "sloika" which translates as "layered pastry".

The last stage of a modern bomb is the outer shell known is the "tamper". This is a dense metal that keeps the bomb components in close enough proximity (for a time measured in microseconds) to interact through sheer inertia. The tamper is probably the heaviest component of the bomb by large margin and is lead if you want a "clean" bomb with relatively low levels of fission by-products or uranium if you want another doubling stage of power and can stand the fallout of a "dirty" bomb.

The 475kt device John i'd is probably the W88 which replaced the 300 kt W84. The W84 was probably the warhead of the first mirv'ed Minuteman missiles (in the 70s) which replaced an earlier single 1 megaton warhead with 3 300 kt models. The liquid fuel Titan missiles of the early 60s may have had bigger warheads and B-52s of that era may have had 5 and 10 megaton bombs to drop.

The largest bomb ever tested was the Soviet era "Tsar bomba" at 50 megatons and supposedly 30,000 lbs weight just for the bomb. It's outer layer was lead so it could have been 2x as powerful if uranium had been used but the Tu-95 "Bear" heavy bomber that dropped it on the test range allegedly only just survived at the 50 megaton level.

[fredtheobviouspseudonym]

I thought that the TU-95 that dropped the Tsar Bomba was caught in the explosion & destroyed.

Urban myth?

[Anaraxes]

Originally Posted by fredtheobviouspseudonym

I thought that the TU-95 that dropped the Tsar Bomba was caught in the explosion & destroyed.

Urban myth?

Yes. The bomb was attached to a parachute to buy time for the aircraft. The Tu-95 made it 39 km away at the time of the explosion, and was 115 km away when the shock wave caught up with the fleeing plane. (The plan was for 45 km distance at detonation, with an estimate of a 50% chance of survival.) It did take some damage, and dropped about a kilometer when the shock wave passed the plane, but it survived.

There was also a Tu-16 observer plane that was there to film, take air samples, and so on. It was even further away than the Tu-95, and also survived.

[Johnny1A.2]

Originally Posted by Blood Legend

What modern weapons do we have that impart close to a Gigajoule of damage?
A megajoule?
Kilojoule?

It matters tremendously what form the gigajoule takes. A smaller amount of energy efficiently applied does more damage than a bigger amount inefficiently applied.

At the far end of extremes, a gigajoule of neutrinos wouldn't do anything at all. A lightning bolt and a ton of TNT might be comparable in energy output, but you're more likely to survive a lightning strike than being at ground zero of a 1 ton TNT blast (and if conditions are right, the lightning strike might even not do any damage at all). The TNT blast has far more energy than a rifle shot, but a well-used rifle will kill you at a greater distance than the TNT will.

[Prince Charon]

Originally Posted by Johnny1A.2

At the far end of extremes, a gigajoule of neutrinos wouldn't do anything at all.

It could be interesting to come up with something that could plausibly be damaged by neutrinos, though (other than by straight GM fiat like 'energy beings naturally interact with neutrinos, and have blasters made of energy that shoot coherent neutrino beams').

[Fred Brackin]

Originally Posted by Prince Charon

It could be interesting to come up with something that could plausibly be damaged by neutrinos, though ').

Since if something damaged whatever was inside a black hole we couldn't see it, the next likely candidate is a neutron star. It might not be a lot of damage but the sort of neutrino flux you'd get from a close-ish supernova might make for a sort of detectable hiccup.

[Anthony]

Originally Posted by Fred Brackin

Since if something damaged whatever was inside a black hole we couldn't see it, the next likely candidate is a neutron star. It might not be a lot of damage but the sort of neutrino flux you'd get from a close-ish supernova might make for a sort of detectable hiccup.

I think I worked out the neutrino flux and interaction chance for a supernova and if you were somehow within a hundred AU or so on and didn't instantly die (maybe binary star and you're behind the other star?) the neutrino flux would kill you from radiation damage.

[johndallman]

Originally Posted by Prince Charon

It could be interesting to come up with something that could plausibly be damaged by neutrinos . . .

Near any reasonably warm star, there are a lot of neutrinos around already.

[Varyon]

Originally Posted by johndallman

Near any reasonably warm star, there are a lot of neutrinos around already.

Near any reasonably warm star, there's a lot of visible-spectrum photons around as well. Maybe you simply need a higher concentration of neutrinos than what's present at daytime on a habitable planet to affect whatever the theoretical thing that is susceptible to damage from neutrinos is - much as you typically need a higher concentration of photons (such as in a high-powered laser) to appreciably damage typical matter.

[Anders]

Originally Posted by edk926

What was the rating of the nukes dropped on Japan in ww2? How powerful would the modern nuke be?

The most powerful nuke ever made was the Tsar Bomba, somewhere in the vicinity of 50-58 Megatons of TNT. In theory it could have had a 100 MT yield, but in order to reduce radioactive fallout one of the mechanisms for boosting yield was left out. 50 MT is about 210 Petajoules, or 210,000 Gigajoules.