Patrick Steffanic

Physicist · systems architect · Knoxville, Tennessee

In order to understand a system, you have to measure the right thing.

I am Patrick Steffanic, a physicist turned systems architect. For eleven years I measured a state of matter that nobody can observe directly. I now apply the same approach to a different kind of system, which is the software and the people inside a company. In both cases the job is to work out what to measure, build the instrument that does the measuring, and then automate whatever the measurement makes obvious. I do this at Nexus, a decision intelligence platform for K-12 school districts. District leaders there ask questions of their own data and get answers they can act on, without waiting in a report queue.

I love to chat about exciting ideas and opportunities to work with interesting people.

Charged particles leaving a collision, as the detector reconstructs them. Drawn live in your browser, and every reload is a different event.

I.Measuring what you cannot observe

The hard part of any measurement is deciding what to measure, and that decision comes before you know the question.

I spent my PhD measuring the quark-gluon plasma, a state of matter that exists for a tiny fraction of a second after two lead nuclei collide. Nobody has ever observed it directly. Everything we know about it is inferred afterward from what the detector happened to record at the moment of the collision. That detector was designed and built years before I thought of the question I ended up asking. In order to answer a question that nobody has asked yet, somebody has to decide what to measure and then build the instrument that measures it, which is both the hardest part of the work and the part that I find the most interesting.

In 2022 I ran detector operations for the ALICE experiment at CERN, coordinating a crew of twelve people from a dozen different countries around the clock for two weeks. Two things from that job have stayed with me. Good procedure and well-trained people together remove the great majority of decisions from the table, leaving only the decisions that genuinely deserve a person's attention. Additionally, any decision that should have been written down as a procedure and was not will cost you again, every single time it comes up.

time projection chamber · lead–lead · 5.02 TeV pionkaonproton

What the detector actually records: charge deposited in silicon, time of flight, and energy in the calorimeters. The physics is inferred from those numbers afterward.

II.A company is a system

In January 2025 I joined Nexus, and I started treating the company itself as the experiment.

sisassessmentfinancehrtransport district systems dozens per district ingestionevery nightone shape trustis it fresh?is it right?self-healing proposes a fix · a person says yes dashboardsdecisionsforecasts acts, not answers the company itself client work in one place · cost to serve what is slipping, and who is on it

The company, January 2025

January 2025data scientist

The measurement that mattered

Nexus is a decision intelligence platform for K-12 school districts. That means a district's data has to arrive correctly and on time before anything else we build has any value at all. When I joined as a data scientist, the nightly integrations that feed every one of our products were outgrowing the architecture they had originally been built on, and keeping them running was consuming a large share of our most senior engineering time. That turned out to be the measurement that mattered. The rate at which we could bring on a new district was also the rate at which the company could grow.

Summer 2025data scientist

Rebuilding the part that set the rate

Over the summer I designed the ingestion platform that every district now runs on. The constraint I set was that somebody other than me had to be able to onboard a district with it. That meant the vendor-specific knowledge had to live in configuration rather than in code, and every change had to prove itself against production data before shipping. It became the standard path for the whole integration team, which is what actually moved the rate. The senior engineering time it gave back went into building product instead, and in October I became Head of Data.

Early 2026head of data

Correctness as a property of the system

A data company really only sells one thing, which is the assurance that the number is right. In order to make that true by construction rather than by vigilance, I built the layer that watches the pipeline itself. It notices when a source has quietly stopped updating, it distinguishes a legitimately empty file from a missing one, and when a job does fail it identifies the cause, drafts the fix, tests that fix against the data that broke it, and hands a person a change to approve. The diagnosis is done by the system and the decision is kept by a person, which is the arrangement I would like everywhere. In January I became Senior Systems Architect.

Summer 2026systems architect

Putting the data to work

Once the data could be trusted, it could start doing work rather than simply being reported on. District leaders now read board and principal dashboards every morning. A transportation bidding process runs end to end, because the coordinator who had been doing it by hand asked for a system that decides rather than one that drafts. A graduation-likelihood model is calibrated carefully enough that a district can defend it in front of its own school board. Underneath all of that, I spent a good deal of the year on the platform itself. I split the nightly run across two pods and two queues on Kubernetes, added an admission gate that bounds total memory rather than raising the limit, and rewrote the most expensive paths, including one transform that peaked at 16 GB and now peaks at 2.4 GB. Treating Azure cost and capacity as engineering targets, rather than as a budget line somebody else owns, is what let the fleet keep growing on the hardware we already had.

Nowsenior systems architect

The instruments pointed at Nexus

Most recently I built the platform that Nexus uses to see itself. It pulls every piece of client work out of the four systems we track it in, sweeps the team's calendars each night to attribute client meetings by attendee domain, and links work items to each other and to the meetings they came from. On top of that sits a weekly review which puts person-days per client against what that client pays, with the methodology printed on the page so that anybody can argue with it. Building the reporting turned up two problems in the underlying data, including a thirty-second network blip that had quietly dropped about twenty person-days. A company that can see itself makes noticeably better decisions, and I have really enjoyed watching ours start to.

III.How I work

Three principles, which I apply to every system I work on.

Measurement comes first

Before I change anything I want to know what the system is actually doing, as opposed to what it was designed to do or what everybody believes it does. The right measurement almost always turns out to be worth more than the clever fix, and every valuable thing I have built started out as instrumentation that was originally meant to answer a much smaller question.

Automation before process

The order matters a great deal here. Systematize the work first, automate it second, and then build the process that holds the quality at least as high as a person would have. The people who are freed up in the process take on new work, and that new work becomes the next thing to automate. In this way a small team keeps taking on more without having to hire in proportion.

Experts own the decision

I will never personally know most of what a given decision requires, but the person who has been running that process for ten years usually does. The job is to ask them well, build what they actually asked for rather than what I happened to find interesting, and then own the result. A computer cannot be held accountable, so a person makes the decision once and the system carries that decision out every day afterward.

These days a good part of my crew is machines. Agents with budgets and guardrails run the procedure, and I decide what they work on and whether the result holds up. It is very close to the job I had in the control room at CERN. Working with the tools available in this space has been genuinely incredible. It is also the reason I now care a great deal more about clarity, precision, and foresight than about how quickly I can type.

IV.What's next

I have done this for a detector and for a company, and I would love to do it for a business at scale.

The pattern does not appear to change with size. Make the system visible, rebuild whichever part is setting the rate, automate the procedure, and keep the people on the decisions that genuinely require judgment. I believe that a small team can run a very large business this way, and I would like to be part of building one that does.

If you are building something and you want somebody who can design the whole system and still fix the bug at the bottom of it, I would love to hear from you. steffaniccodes@gmail.com

Things I want to exist

  • Model architectures that deliver large-transformer quality on a laptop.
  • Continuous-learning systems that are good enough for hands-off automation and for genuinely useful life assistants.
  • A universal API for all of my own personal data.

A problem I would love help with

TownSim consists of three parts, which are a deterministic engine that holds the truth, a non-deterministic engine that resolves what happens next, and LLM-driven characters who do the talking, all of it running on scenarios that the community writes. If you are an AI engineer who knows how to make a world feel real, I would love to hear from you.

Now

September 21, 2026

Working on. At Nexus, the systems that let a small team do considerably more than its size would suggest. That means an internal agent which can answer questions about every system the company runs, from client usage through to our own operational data, along with the process around tracking, prioritizing, and finishing client work. On my own time, a local-first LLM game engine built around community scenarios, plus some personal data collection for a life assistant.

Thinking about. How systems, people, and customers interact inside a business. I am building my own model of what makes one effective, and I expect to be wrong about a good deal of it.

Happy to talk about. What comes next in AI, how to build systems around intelligence engines, and where software, hardware, and technology at large appear to be heading.

TownSim active

A single-player town in which a deterministic engine holds the truth and LLM-driven characters do the talking, with scenarios and content packs that anyone can write. The engine owns the state, and obviously the model does not get to invent it.

Life OS paused

A chief-of-staff agent that keeps my commitments outside of my head. It surfaces the quiet but important ones at the point where they can still be acted on, and it is built around open loops rather than around events.

Writing

Books that shaped how I think