How close to modern technology can humans plausibly get without discovering nukes?

Question

This is for humans living on a similar planet as earth and similar tech-development (in my setting, there is magic, but I want the most ideal, non-magic answer to this so I can better tweak the other factors in my setting to achieve the level of technological development I want.)

What is a plausible level of technological development humans could have without discovering nuclear bombs? I'm talking mainly about technology developed post-1945 in our real world. How plausible are the following:

• Computers
• "Modern" weaponry
• Spaceflight, and space-related technology like satellite television, GPS, cell phones, etc. (This would require understanding relativity)
• "Quantum" technology, like MRI machines or lasers (it could be said that computing is not possible without semiconductors, which require quantum mechanics to understand. So likely, this world has a good understanding of quantum mechanics)
• Nuclear power (while nuclear weapons and peaceful nuclear power are different, I'm not sure if it's possible at all to have one without the other. it's probably easier to make nuclear bombs than nuclear power plants, or so it seems from real-world development)

If there could be a reason why researchers in this world are overlooking nuclear bombs, then feel free to include that. Of course, it is possible to build all this technology without building a nuclear bomb, but whether it is plausible that researchers in this world would overlook/not be able to make a nuclear bomb while making other, more technologically advanced things is harder for me to say.

Another way to look at this question is: What would the Cold War have been like if there was no MAD? However, that is not the question I'm asking, but it is a way to think about this situation.

(One possible answer that I do not accept: There is complete peace in this world, so there is no incentive to create a nuclear weapon. This world is not at peace and there are multiple powers vying for global dominance.)

Answer 1

Not enough enthusiasm, commitment, money or brains

The Manhattan Project succeeded in developing atomic weapons - not "discovering" them - through a combination of "ideal" circumstances - influential scientists who pushed the idea; a fully committed government; near-limitless resources to throw at problems; and a large collection of brilliant scientific minds. If any of those four ingredients had been missing then atomic weapons would not have been produced as early as they were, or possibly ever. For example, look at the German nuclear weapons program or the Soviet program, or think about how the cash-strapped British would have gone if they had tried to go it alone in developing "the Bomb".

The effort required cannot be judged by looking at who has developed nuclear weapons now, firstly because significant information was prematurely declassified by the USA after the Soviets developed atomic weapons, which gave all subsequent attempts a huge head start. (The reasoning at the time was that it did not matter who knew once the USSR did. So much information was declassified that a US college student was able to design a nuclear weapon for his thesis.) The other issue is that state-level actors and others today who decide to develop nuclear weapons are starting with the information that it can be done. They know that they will literally get a lot of bang for their buck, even if it takes a lot of bucks.

How long the non-development of nuclear weapons could last is unclear. There is no feasible way to avoid scientists understanding the potential of nuclear weapons or nuclear power generation once past the turn of the 20th Century in Earth terms. As increased computing power becomes available, the cost of some aspects of design and development will drop, but some aspects - such as developing uranium mines and refineries and collecting all the required human brainpower - will remain expensive.

In summary, separate the ingredients that allow nuclear weapons to be developed and you could plausibly have a 21st Century-equivalent world without them. Any world will have economic superpower/s, so make sure that the superpower/s:

• Do not have a government that maintains its focus on long-term, speculative research programs and/or
• Do not attract the best scientific minds.

Answer 2

At the beginning of WWII, the 'Domesday weapon' was seen to be poison gas. The Axis probably had superior nerve gas. The Allies may have had deployable anthrax. Neither side used their weapons because they feared the other side would use theirs without restraint. MAD predates nuclear weapons.

Going down your list...

• Computers

People have seen the possibilities of computers long before the technology. The UK's atomic weapons were developed with the help of a mechanical integrator made out of 10 tons of Meccano. If you want to calculate something, people will find a way.

• Modern weaponry...

Aircraft were steadily improved. It was clear that you could build something better and faster than what you had.

Rockets were the real surprise: Germany had been limited by the Treaty of Versailles in its conventional weapons, but rockets were excluded. The British had used large fireworks called 'conrgeves' after their developer. These were much more portable than a cannon, but they were inaccurate. So, it came as a genuine shock that a 'rocket' was the size of a 3-storey building, could climb to a height of 50 miles at 3500 mph, steered by a sophisticated analogue computer. Rockets might have taken a lot longer to develop without the V2 as an example.

• Quantum technology

This was being looked at shortly after WW1. The photoelectric effect was the first indication that light might be a particle. It then became irresible to find out whether it was a particle or a wave, leading eventually to the bizarre truth that it was either. I think quantum theory would always be discovered.

• Nuclear Power

In the early days, nuclear power was a spin-off from weapons. The UK's original Sizewall 'A' reactor dumped all its energy into the sea, because it was felt that the power output generating electricity would give away important intelligence about how much it was doing. Without nuclear weapons, I think it was quite possible people would have carried on using fossil fuels, and then renewable resources.

My answer is your people would develop computers to build nukes, aircraft to deliver nukes, though maybe not rockets without the V2. They would have had the atomic and quantum theory. But they might not have taken the leap of faith to building an 'A' bomb, and then the 'H' bomb without the Cold War. If their WWII had ended rather than started with the poison gas stand-off then nukes might not have happened, and nuclear power would not have happened as a result.

Answer 3

As close as you want and beyond.

The planet may not have easily accessible uranium, plutonium and similar elements suitable for making nukes.

These elements are formed through r-process (rapid neutron capture) in supernovae and neutron star mergers. These events are relatively rare, thus heavier elements are generally much more rare then lighter ones (iron and below). Over time matter coalesces into new star systems, a new star is formed, then planets.

The star system may have much less of heavier elements to begin with and, depending on geological processes during and after the planet formation, they can end up in the planet core, thousands kilometers below the surface.

So, even though the scientists have the general idea that theoretically something interesting may happen when you make a huge pile of uranium, they don't have enough material to do anything about it.

Alternatively, an alien race raided the accretion disk or the young planet and snatched every atom of heavy elements they could put their tentacles on.

Answer 4

Nuclear bombs set the planet on fire

In earth, there was a fear that nuclear bombs would cause a chain reaction with hydrogen nuclei, causing a large mass explosion.

Physics in your world is slightly different, and clouds and large bodies of water tend to explode when hit by nuclear bombs. Small scale testing of nuclear weapons in the past happened, but when the extremely destructive nature was discovered, further experimentation was banned by all.