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Y CombinatorInside The Hard Tech Startups Turning Sci-Fi Into Reality
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Hard tech is worth doing: slinging atoms, not just bits
The hosts frame hard tech as a high-impact alternative to “optimizing ads,” and set the tone: ambitious engineering can materially reshape society. They tease the core thesis—these sci‑fi ideas are increasingly buildable by small teams with the right approach.
- •YC has major wins in hard tech alongside famous software companies
- •Hard tech as solving humanity-scale problems (energy, climate, space)
- •Encouragement for elite engineers to build in the physical world
- •Premise: big outcomes are possible with the right milestones
Hard tech milestones in a 3‑month batch: LOIs, cost models, and proof you can build
They explain how Demo Day expectations differ for hard tech: revenue often isn’t possible yet, so founders must show credible commercial demand and technical feasibility. The discussion emphasizes serious LOIs, unit economics, and a concrete de-risking plan.
- •Commercial traction can be LOIs with real dollar values and credible customers
- •Hard tech must also show financial viability (unit cost and scaling logic)
- •Technical milestone: prove a small-scale “kernel of truth” that works
- •Hard tech pitches focus on “why you?” more than “why now?”
YC’s model: stop trying to raise $50M first—think like a software company
Jared and Diana describe a common failure mode: founders assume they need tens of millions immediately. YC pushes them to carve off a tractable first step that can be done fast and cheaply, creating momentum and investor belief.
- •Hard tech founders often overestimate the money needed for the first milestone
- •There is always a peel-off milestone achievable with ~$500K and ~3 months
- •Mental shift: fast cadence, ruthless scoping, and concrete deliverables
- •Progress during YC unlocks investors who previously wouldn’t fund the idea
A presentation trick: prove speed vs. “normal timelines” (the Brex timeline analogy)
Harj shares a tactic for investor storytelling: contrast the typical industry timeline/cost with what the team achieved in YC. This reframes the pitch around founder capability and execution speed, directly answering “why you?”
- •Use a visual timeline comparing standard vs. your compressed timeline
- •Include cost comparison (e.g., $50M/12 months vs. $500K/3 months)
- •Demonstrates founder advantage, not just idea ambition
- •Builds an enduring operating habit: faster and cheaper forever
Example: Boom Supersonic—de-risking tech and airline demand with a $100M LOI
Boom illustrates how a seemingly billion-dollar project can start with focused de-risking. During YC they pursued both technical credibility and airline willingness to buy, culminating in a pivotal LOI that enabled fundraising.
- •Challenge: supersonic passenger jet is a multi‑billion‑dollar endgame
- •Two de-risk tracks: technical feasibility + commercial demand from airlines
- •Secured a $100M LOI from Richard Branson/Virgin just before Demo Day
- •Outcome: years later, Boom built and flew a real supersonic jet
Example: Cruise—start with a retrofit kit to bootstrap the self-driving vision
Cruise shows the power of choosing a smaller initial product that fits venture timelines while keeping the larger ambition intact. The team’s credibility and early commercialization path helped turn a ‘research project’ into a rapid, large exit.
- •Founder credibility mattered (Kyle’s prior deep technical track record)
- •Initial wedge: highway ADAS retrofit kit for Audi S4 owners
- •Commercial validation via early demand (Kickstarter-era validation)
- •Result: acquired for ~ $1B within a few years; self-driving now mainstream
Space playbook: Astranis and the ecosystem shift enabled by cheaper launches
They describe why space has become a fertile hard tech category: launch costs and access improved dramatically, creating new business possibilities. Astranis exemplifies capital-efficient scaling from a small satellite built in YC to a satellite factory.
- •Astranis insight: many small satellites vs. few massive ones (mainframes→servers analogy)
- •Batch milestone: build a functioning satellite in 3 months; launch soon after
- •Telecom satellites can be profitable early with real customers
- •SpaceX launch availability catalyzed a broader space startup ecosystem
Asteroid mining and risk breakdown: invest by stacking achievable tranches
AstroForge prompts a discussion on how investors evaluate extreme technical bets. The answer: identify near-term proofs (fly out and back, validate ore concentration) and recognize optionality (including regulatory/ownership angles).
- •Near-term milestone: reach an asteroid and return; validate target selection
- •Multiple monetization paths; regulatory notion of ownership rights
- •Expected value thinking: low probability, enormous upside
- •General method: break huge technical risk into sequential, provable steps
More aerospace: Relativity Space and proving feasibility with a scaled 3D-printed engine
Relativity demonstrates how to validate a radical manufacturing thesis with a tangible artifact. Their Demo Day proof (a real small engine) translated into later real-world breakthroughs—launching a mostly 3D-printed rocket.
- •Winter ’16 had multiple breakout aerospace companies due to timing/tailwinds
- •Demo Day milestone: 3D print a rocket engine (scaled but real)
- •Investors could see a physical proof with correct geometry and components
- •Later achievement: launched an almost entirely 3D-printed rocket
Climate & energy hard tech: electric planes and retrofitting heavy emitters
They shift to climate: companies can win by making known solutions cheaper and by riding regulatory tailwinds. Examples span electric regional aircraft and retrofit carbon-capture systems for trucks and ships, pairing LOIs with early pilots.
- •Heart Aerospace: electrifying regional flights; airline LOIs + regulatory tailwinds
- •Funding reality: later stages need customers, purchase orders, and grants
- •Remora: mobile carbon capture retrofit for semis; achieved ~80% capture in practice
- •Seabound: ship retrofit CO2 reduction; hard industry entry via LOIs and pilots
Chemistry at startup speed: Solugen’s scale-up ladder and revenue from day one
Solugen is presented as a model for capital-efficient hard tech: start at beaker scale, sell immediately, and scale stepwise. Their discipline—never selling at a loss—helped turn ‘sci‑fi’ chemistry into a durable industrial business.
- •Start with the smallest viable proof (a beaker of hydrogen peroxide)
- •Demo Day goal: tabletop to garage-scale production (gallons)
- •Sell early and avoid unit-negative scaling; revenue from the beginning
- •Result: scaled to a major chemical plant with healthy revenues
Current-batch robotics: Kscale’s open-source hardware strategy to build a data flywheel
Kscale shows how a humanoid-robot vision can be reframed into a near-term, capital-light plan. By open-sourcing designs and rallying a builder community, they aim to crowdsource hardware deployment while centralizing value in the foundation model.
- •Initial challenge: founder wanted huge funding; YC pushes smaller milestone path
- •Focus on a perception foundation model, proven through real robots in the loop
- •Build first ~10 robots; open-source hardware designs to spark a community
- •Community-built robots run Kscale’s model, creating a scalable data advantage
Current-batch aerospace: Astromechanica’s ‘innovate on few things’ hardware rule + tight beachhead
Astromechanica’s approach is to minimize custom hardware and move quickly via simulation and off-the-shelf components. Commercially, they resist boiling the ocean by choosing one sharp initial market—payload launch—while keeping a Boeing-scale ambition.
- •Breakthrough: efficient electric jet engine across speeds (hard optimization problem)
- •Execution tactic: use off-the-shelf parts; innovate on 1–2 core components
- •Commercial wedge: focus on launching payloads to orbit first
- •Use LOIs/revenue from the wedge to finance broader aircraft ambitions (Tesla-like strategy)
Big-picture synthesis: hard tech risk, founder vision, and the non-Elon fundraising playbook
They conclude by contrasting risk profiles: hard tech often has high technical risk but low market risk, and YC data suggests success rates comparable to software. The closing advice: decompose the problem, prove stepwise progress, and build real businesses—not fundraising exercises.
- •Hard tech founders often ‘live in the future’ with high clarity of end-state
- •Risk tradeoff: technical risk vs. software’s market risk; outcomes can be a wash
- •Mission and ambition help recruit talent, partners, and attention
- •If you’re not a natural fundraiser: win via discipline, small milestones, and speed
