With Season 3 of Apple TV’s Silo series over, it’ll be fun to compare its nanobots with the real thing—not to nitpick, but because a lot of people are asking whether nanobots actually exist. Even as a book reader, I loved the final two episodes of Silo Season 3, and I can’t wait for Season 4.

However, when it comes to sci-fi, a little ignorance can be bliss. It’s kinda like watching MythBusters debunk Hollywood movies: probably better to enjoy the movie before MythBusters crushes the magic. So, if you don’t know how to switch off your critical thinking and just enjoy the ride, you might want to stop reading here.

So are Nanobots Real?

The short answer is yes—but not like the nanobots in Silo. Real nano- and micromachines already have remarkable medical applications, including targeted drug delivery and experimental cancer treatment. What they cannot do is think, identify people and repair or destroy almost anything on command.

Yes, there are nanometer-sized machines with real-world applications, some of them mind-blowing. Are they like the nanobots in sci-fi? No.

Will they ever be like the nanobots in Silo? I think practical limitations pretty much rule that out. We already know what extremely capable microscopic machines look like: cells and bacteria. They perform feats that would be astonishing in an engineered machine of the same size. Yet even these complex systems cannot independently read the DNA inside a cell, decide whether you are a good guy or a bad guy, repair you if you are good, and wreak havoc if you are not and everything else the bots can do in Silo—all while being small enough to fit inside that cell. The real-world medical applications are staggering, but diagnosis and a tailored fix would still require a surgeon or an expert analytical system. [1–4]

They could theoretically make nanoweapons because it is so much easier to make a hammer than a Swiss watch. But even that is impractical. It would be so much easier to modify a nasty germ in a lab. Even then, I doubt germ warfare would wipe out every last enemy. [5]

The Mind-Blowing Reality of Nanotechnology

But there are a lot of smart people out there pushing the boundaries.

Bladder Cancer Treatment

This one already sounds like something from a sci-fi film. Researchers built tiny porous silica spheres that use an enzyme to react with urea in urine, so they can propel themselves through the bladder. The spheres carry radioactive iodine and gather around a tumor, delivering the treatment where it is needed. In mice, a single dose reduced tumor volume by about 90%. That is genuinely mind-blowing—but it is still preclinical research, not a treatment you can book at the hospital tomorrow. [6]

Targeted Drug Delivery

This is probably the closest real-world cousin to the medical nanobots we imagine. Researchers are developing magnetically guided microrobots that can carry a drug through complicated passages in the body and release it at a chosen spot. The big attraction is simple: put more medicine where it is needed and less everywhere else. That could reduce the off-target effects of treatments such as chemotherapy. Systems like this have now been tested in models of human blood vessels and in large animals, but they are still experimental rather than routine clinical care. [7–9]

Clearing Blood Clots

Then there are microrobots designed to tackle blood clots. In laboratory and animal research, magnetically controlled micro- and nanorobotic systems have carried clot-dissolving drugs to thrombi and accelerated clot breakdown. That is impressive, but researchers are clear that navigation, retrieval or clearance, safety and control still have to be solved before these systems become routine clinical care. So, yes, the idea is real. The hospital-ready version is not—at least not yet. [10–12]

Final Thoughts

I find it difficult to imagine that the nanomachines of Silo could be so widely coordinated and precisely controlled—able to recognize targets, repair bodies, attack technology and remain effective across generations. But that doesn’t stop me from enjoying the Silo series. Good science fiction doesn’t need every invention to be possible; it needs the impossible parts to feel believable. I hope my own story, Dream Job, feels as grounded as Silo does.

In Plot Analysis for the Silo Universe Stories in ‘Machine Learning‘ I give my thoughts on a series of short stories that extend beyond the initial triogy.

In The Nanobots of Silo, Explained I discuss the origin and roll of nanobots in the Silo universe.