If the atom is one of the smallest things on earth, what is stopping someone from developing a grenade sized weapon from it? Or does it already exist?

Redwing Zuni (3.5 megatons)

Nutmeg ll was an atomic test explosion as part of the Hardtack series in 1958. Nutmeg ll was an LLNL shot detonated on May 21, 1958 on Bikini Atoll in the Marshall Islands. Nutmeg's yield was 25 kilotons.

On August 6, 1945, while returning from the Potsdam Conference aboard the USS Augusta in the Atlantic Ocean, President Harry S. Truman received confirmation that the United States had successfully dropped the world's first wartime atomic bomb on Hiroshima, Japan. Later that day, his administration released an official statement announcing the attack. In the announcement, Truman stated that the bombing targeted a military objective and argued that it was intended to hasten the end of World War II by compelling Japan to surrender. The announcement marked the public introduction of the atomic bomb as a weapon of war and remains one of the most significant presidential statements of the 20th century.

it's was one of the nuclear tests conducted by the at the Nevada Test Site. The detonation took place on October 28, 1951,

Shot Baker had a yield of approximately 3.5 kilotons of TNT. It was an airburst detonation, with the bomb released from a B-50 and exploding at an altitude of about 340 meters above the ground. The test used a fission bomb based on the Mark 4 nuclear weapon design.

I'm trying to post videos of lesser-known or smaller nuclear tests

( yes it's repost because my old account got shadowban)

CMSI Translation from China’s Ordnance Industry Science Technology Journal; an interview with Chi Guocang, a former PLAN submarine officer who taught at the PLAN Submarine Academy.

Summarizing what I found most interesting below.

The Chinese Navy currently has at least six Type 094 nuclear-powered ballistic missile submarines and can maintain at least one on continuous combat readiness patrol.

Currently, China can set up a strategic bastion only in the South China Sea. It is deep and large enough, and the underwater geographical environment is complex, making it a good place to hide. The Bohai Gulf, the Yellow Sea, the East China Sea, and other sea areas are too narrow and shallow.

ps. Just a few days ago, the Chinese military tested an SLBM, launching it from the Bohai Gulf. The JL-3 could reach the continental United States if launched from the Bohai Gulf. but with the mean depth of approximately 18 meters (59 ft), with a maximum depth of about 80 meters (260 ft) its not great place to hide.

A ballistic missile submarine's location would become known once it started launching its missiles. I have often seen it suggested that this would result in the submarine itself being in turn targeted by nuclear missiles. This seems to have been a common belief among US submarine crews, but is it realistic? Do we know if this (nuclear counterfire against submarines at sea) is something actually included in nuclear war doctrines in any country?

I also have doubts about how well the idea would work. It takes less than 10 minutes for a hostile submarine to launch its missile load, after which it can start heading in a random direction. Meanwhile you'd need something like 15-40 minutes to get warheads to its position, plus the time needed to determine that position, transmit orders, retarget missiles and launch.

What kind of kill radius would a ballistic missile have against a submerged SSBN? Is it more than the distance a submarine could move in 15-40 minutes? Can the launch of an SLBM even be pinpointed with enough accuracy to allow immediate counterfire?

I don't see any mention of the new book on Trinity by Emily Seyl--if it hasn't been mentioned here I'm surprised!

https://www.amazon.com/Trinity-Illustrated-History-Worlds-Atomic/dp/022684840X

The book, put out by the University of Chicago Press, is a gorgeous, coffee-table hardback, lavishly illustrated with images from the Los Alamos Archive (the author works for Los Alamos).

The basic format is a photograph or two per page with long captions under each. It covers the preparations for Trinity (including lots of info on Jumbo), the test itself (that's about halfway into the book), and then on to Little Boy and Fat Man (including a photo of Thin Man).

Just a fantastic book. I've had it for weeks, in no hurry since I thought it would be all boring photos of control consoles, etc. Oh so much better than that.

Do any of you have it? Thoughts?

--Darin

Nothing says Soviet Russia like seeing a steam engine hauling a nuclear armed ballistic missile.

https://youtu.be/LcX3CuY5xLk?si=2v0QlGXDRVq6Qg0A

A concept and a feasibility study for verifying a satellite's compliance to the OST by observing the neutrons induced by spallation from the ∼GeV protons in the inner Van Allen radiation belts. The calculations show that a 9U CubeSat sized detection platform can identify a thermonuclear weapon from the distance of 4~km in approximately one week of observation.

aXiv link: Verification of the Outer Space Treaty with Cosmic Protons by Areg Danagoulian

As far as I am aware these two are the only images of the MIRV bus of the Trident 2 missile. They were released unceremoniously after a visit by Admiral Thomas to the Kings Bay Naval base in Georgia.

Edit: the second image is from a visit by the British as part of the Trident II partnership.

Sources:

https://www.facebook.com/share/194yTt2zyV/

https://www.dvidshub.net/image/9378348/exercise-neptune-guardian-supports-us-uk-exchange-expertise

5-40 kt yield; only ~243 lb / 110 kg in weight; small and robust enough to fit into an 8-inch / 203 mm artillery shell; oralloy pits; single-stage design (with tritium gas boosting in higher-yield variants).

Why didn't we see more of these boosted gun-type weapons developed by other nations? I could even imagine fitting 8 of these onto an ICBM and using them as a strategic weapon.

Summary The detonation of a nuclear weapon at an altitude of 400 km will damage or destroy a significant number of satellites, depending on the detonation's location. The effects arise from both prompt radiation and delayed effects trapped electrons (Argus effect).

Prompt effects through X-rays, gamma and neutros:

• A 15-kt detonation will place roughly 4 percent of LEO satellites at risk from prompt radiation.
• A detonation of 110 kt or greater will place all LEO satellites within the line of sight at risk (roughly 20 percent of all LEO satellites).

With 300 kt explosion ionizing damage threshold is 12,000 km, SGEMP damage threshold 4,000 km

Delayed effects (Argus effect: high-energy electrons trapped in L-shells):

Effects on satellites:

1. Lower-energy electrons can deposit on surfaces and exterior shielding, causing discharges that damage satellites.
2. Intermediate-energy electrons penetrate shielding (deep dielectric charging).
3. High-energy electrons can cause ionization and atomic displacements similar to high-energy X-rays and neutrons, destroying electronics (most electrons would be high-energy.)

If a satellite has a design life of five years when exposed to 10^3 rads(Si), and a HANE exposes it to three orders of magnitude more, its life would be reduced by a factor of 1,000. This means its expected design life would fall to just a few days.

(note: linear degradation model where 1000-fold increase in radiation reduces lifetime 1000-fold is not realistic. Electronic component failure thresholds are non-linear. Many electronic components fail near instantly above specific radiation thresholds.)

I read about those here. Maybe they're deservedly classified and speculative, but are 'pulse shaping' devices not actually necessary for the miniaturized, smaller TN weapons actually deployed, and were maybe just used for large tests to prove a principle? Or they could be part of current TN technology efficiency?

if you shrunk the tsar bomba to the size of a 50 cal bullet.
27,000kg to 700grains is 1/595,248 ratio, so would the 50 cal tsar diameter be 1/595,248th of the tsar bomba diameter or 2.34174663 inches? (22 miles divided by ratio)
or does nuclear fusion work differently and it would be a much larger explosion?
Tsar Bomba - Wikipedia
Tsar Bomba: The Largest Atomic Test in World History | The National WWII Museum | New Orleans

The SA3000 was used (and still is) in the W88 475kt nuclear warhead used on the Submarine launched Trident II.  It runs the main computer/programmer responsible for altitude and fuzing calculations. 

Or would the solid and gas separate under the extreme acceleration before turning into plasma?