Physics for Venture Capitalists

VCs stress that they’re not in the business of evaluating technology. Few failures of startups are due to bad tech. Leo Polovets at Susa Ventures says technical diligence is a waste of time because few startups have significant technical risk. Success hinges on knowing customers’ needs, efficiently addressing those needs, hiring well, minding customer acquisition, and having a clue about management and governance.

In the dot-com era, I did tech diligence for Internet Capital Group. They invested in everything I said no to. Every one of those startups failed, likely for business management reasons. Had bad management not killed them, their bad tech would have in many cases. Are things different now?

Polovets is surely right in the domain of software. But hardware is making a comeback, even in Silicon Valley. A key difference between diligence on hardware and software startups is that software technology barely relies on the laws of nature. Hardware does. Hardware is dependent on science in a way software isn’t.

Silicon Valley’s love affairs with innovation and design thinking (the former being a retrospective judgement after market success, the latter mostly marketing jargon) leads tech enthusiasts and investors to believe that we can do anything given enough creativity. Creativity can in fact come up with new laws of nature. Isaac Newton and Albert Einstein did it. Their creativity was different in kind from that of the Wright Brothers and Elon Musk. Those innovators don’t change laws of nature; they are very tightly bound by them.

You see the impact of innovation overdose in responses to anything cautious of overoptimism in technology. Warp drive has to be real, right? It was already imagined back when William Shattner could do somersaults.

When the Solar Impulse aircraft achieved 400 miles non-stop, enthusiasts demanded solar passenger planes. Solar Impulse has the wingspan of an A380 (800 passengers) but weighs less than my car. When the Washingon Post made the mildly understated point that solar powered planes were a long way from carrying passengers, an indignant reader scorned their pessimism: “I can see the WP headline from 1903: ‘Wright Flyer still a long way from carrying passengers’. Nothing like a good dose of negativity.”

Another reader responded, noting that theoretical limits would give a large airliner coated with cells maybe 30 kilowatts of sun power, but it takes about 100 megawatts to get off the runway. Another enthusiast, clearly innocent of physics, said he disagreed with this answer because it addressed current technology and “best case.” Here we see a disconnect between two understandings of best case, one pointing to hard limits imposed by nature, the other to soft limits imposed by manufacturing and limits of current engineering know-how.

What’s a law of nature?

Law of nature doesn’t have a tight definition. But in science it usually means generalities drawn from a very large body of evidence. Laws in this sense must be universal, omnipotent, and absolute – true everywhere for all time, no exceptions. Laws of nature don’t happen to be true; they have to be true (see footnote*). They are true in both main philosophical senses of “true”: correspondence and coherence. To the best of our ability, they correspond with reality from a gods’ eye perspective; and they cohere, in the sense that each gets along with every other law of nature, allowing a coherent picture of how the universe works. The laws are interdependent.

Now we’ve gotten laws wrong in the past, so our current laws may someday be overturned too. But such scientific disruptions are rare indeed – a big one in 1687 (Newton) and another in 1905 (Einstein). Lesser laws rely on – and are consistent with – greater ones. The laws of physics erect barriers to engineering advancement. Betting on new laws of physics – as cold fusion and free-energy investors have done – is a very long shot.

As an example of what flows from laws of nature, most gasoline engines (Otto cycle) have a top theoretical efficiency of about 47%. No innovative engineering prowess can do better. Material and temperature limitations reduce that further. All metals melt at some temperature, and laws of physics tell us we’ll find no new stable elements for building engines – even in distant galaxies. Moore’s law, by the way, is not in any sense a law in the way laws of nature are laws.

The Betz limit tells us that no windmill will ever convert more than 59.3% of the wind’s kinetic energy into electricity – not here, not on Jupiter, not with curvy carbon nanotube blades, not coated with dilythium crystals. This limit doesn’t come from measurement; it comes from deduction and the laws of nature. The Shockley-Queisser limit tells us no single-layer photovoltaic cell will ever convert more than 33.7% of the solar energy hitting it into electricity. Gaia be damned, but we’re stuck with physics, and physics trumps design thinking.

So while funding would grind to a halt if investors dove into the details of pn-junctions in chalcopyrite semiconductors, they probably should be cautious of startups that, as judged by a Physics 101 student, are found to flout any fundamental laws of nature. That is, unless they’re fixing to jump in early, ride the hype cycle to the peak of expectation, and then bail out before the other investors catch on. They’d never do that, right?

Solyndra’s sales figures

In Solyndra‘s abundant autopsies we read that those crooks duped the DoE about sales volume and profits. An instant Wall Street darling, Solyndra was named one of 50 most innovative companies by Technology Review. Later, the Solyndra scandal coverage never mentioned that the idea of cylindrical containers of photovoltaic cells with spaces between them was a dubious means of maximizing incident rays. Yes, some cells in a properly arranged array of tubes would always be perpendicular to the sun (duh), but the surface area of the cells within say 30 degrees of perpendicular to the sun is necessarily (not even physics, just geometry) only one sixth of those on the tube (2 * 30 / 360). The fact that the roof-facing part of the tubes catches some reflected light relies on there being space between the tubes, which obviously aren’t catching those photons directly. A two-layer tube grabs a few more stray photons, but…   Sure, the DoE should have been more suspicious of Solyndra’s bogus bookkeeping; but there’s another lesson in this $2B Silicon Valley sinkhole. Their tech was bullshit.

The story at Abound Solar was surprisingly similar, though more focused on bad engineering than bad science. Claims about energy, given a long history of swindlers, always warrant technical diligence. Upfront Ventures recently lead a $20M B round for uBeam, maker of an ultrasonic charging system. Its high frequency sound vibrations travel across the room to a receiver that can run your iPhone or, someday, as one presentation reported, your flat screen TV, from a distance of four meters. Mark Cuban and Marissa Mayer took the plunge.

Now we can’t totally rule out uBeam’s claims, but simple physics screams out a warning. High frequency sound waves diffuse rapidly in air. And even if they didn’t, a point-source emitter (likely a good model for the uBeam transmitter) obeys the inverse-square law (see Johannes Kepler, 1596). At four meters, the signal is one sixteenth as strong as at one meter. Up close it would fry your brains. Maybe they track the target and focus a beam on it (sounds expensive). But in any case, sound-pressure-level regulations limit transmitter strength. It’s hard to imagine extracting more than a watt or so from across the room. Had Upfront hired a college kid for a few days, they might have spent more wisely and spared uBeam’s CEO the embarrassment of stepping down last summer after missing every target.

Even b-school criticism of Theranos focuses on the firm’s culture of secrecy, Holmes’ poor management practices, and bad hiring, skirting the fact that every med student knew that a drop of blood doesn’t contain enough of the relevant cells to give accurate results.

Homework: Water don’t flow uphill

Now I’m not saying all VC, MBAs, and private equity folk should study much physics. But they should probably know as much physics as I know about convertible notes. They should know that laws of nature exist, and that diligence is due for bold science/technology claims. Start here:

Newton’s 2nd law:

  • Roughly speaking, force = mass times acceleration. F = ma.
  • Important for cars. More here.
  • Practical, though perhaps unintuitive, application: slow down on I-280 when it’s raining.

2nd Law of Thermodynamics:

  • Entropy always increases. No process is thermodynamically reversible. More understandable versions came from Lord Kelvin and Rudolf Clausius.
  • Kelvin: You can’t get any mechanical effect from anything by cooling it below the temperature of its surroundings.
  • Clausius: Without adding energy, heat can never pass from a cold thing to a hot thing.
  • Practical application: in an insulated room, leaving the refrigerator door open will raise the room’s temperature.
  • American frontier version (Locomotive Engineering Vol XXII, 1899): “Water don’t flow uphill.”

_ __________ _

“If someone points out to you that your pet theory of the universe is in disagreement with Maxwell’s equations – then so much the worse for Maxwell’s equations. If it is found to be contradicted by observation – well, these experimentalists do bungle things sometimes. But if your theory is found to be against the Second Law of Thermodynamics I can give you no hope; there is nothing for it but to collapse in deepest humiliation.”
 – Arthur Eddington


*footnote: Critics might point out that the distinction between laws of physics (must be true) and mere facts (happen to be true) of physics seems vague, and that this vagueness robs any real meaning from the concept of laws of physics. Who decides what has to be true instead of what happens to be true? All copper in the universe conducts electricity seems like a law. All trees in my yard are oak does not. How arrogant was Newton to move from observing that f=ma in our little solar system to his proclamation that force equals mass times acceleration in all possible worlds. All laws of science (and all scientific progress) seem to rely on the logical fallacy of affirming the consequent. This wasn’t lost on the ancient anti-sophist Greeks (Plato), the cleverest of the early Christian converts (Saint Jerome) and perceptive postmodernists (Derrida). David Hume’s 1738 A Treatise of Human Nature methodically destroyed the idea that there is any rational basis for the kind of inductive inference on which science is based. But… Hume was no relativist or nihilist. He appears to hold, as Plato did in Theaetetus, that global relativism is self-undermining. In 1951, WVO Quine eloquently exposed the logical flaws of scientific thinking in Two Dogmas of Empiricism, finding real problems with distinctions between truths grounded in meaning and truths grounded in fact. Unpacking that a bit, Quine would say that it is pointless to ask whether f=ma is a law of nature or a just deep empirical observation. He showed that we can combine two statements appearing to be laws together in a way that yielded a statement that had to be merely a fact. Finally, from Thomas Kuhn’s perspective, deciding which generalized observation becomes a law is entirely a social process. Postmodernist and Strong Program adherents then note that this process is governed by local community norms. Cultural relativism follows, and ultimately decays into pure subjectivism: each of us has facts that are true for us but not for each other. Scientists and engineers have found that relativism and subjectivism aren’t so useful for inventing vaccines and making airplanes fly. Despite the epistemological failings, laws of nature work pretty well, they say.




  1. #1 by richard brakeman on August 11, 2019 - 1:34 pm

    When (emerging) technology is the product, whether manifested by hardware or software, technology readiness or maturity could hardly be ignored by an investor team. There surely must be a development plan to bridge the gap from concept to application/production/completed sales. Even the sophisticated (ones) have blind spots, and I have the opportunity to learn from my hard knocks.

    Bill, your writing unfolded truth about the value, yea, necessity for a technology plan having a range of probabilities to achieve time-phased critical success factors; delivery of value, whether incrementally or en masse; and return to investors, unless they consider themselves donors. No different from any other physical (personal) or intellectual property. The case reviews in the article weave a canon of evidence that, in sum, may one day be recognized as among the laws of nature

  2. #2 by Jamie on August 11, 2019 - 9:46 pm

    Bill – next you’re going to tell me that environmentalists should know something about physics too. Correct?

    • #3 by Bill Storage on August 13, 2019 - 8:13 pm

      OK. You’re on.

  3. #4 by sstorage31 on August 12, 2019 - 11:19 am

    I especially liked your explanation of Solyndra and its failure. I always thought that price was its downfall.Politics lost out to Physics.Remember that there was no scandals in the Obama Biden tenure.

    Top leaders of Solyndra solar panel company repeatedly misled federal of…

    Solyndra’s leaders engaged in a “pattern of false and misleading assertions,” a lengthy investigation uncovered.

  4. #5 by Deidre Michaels on August 12, 2019 - 9:39 pm

    “Investors feel excited but incompetent when they encounter sophisticated entrepreneurs well-informed about their industry. This feeling of inadequacy and admiration is a key driver of the investment decision and it is addictive.”

    View at

  5. #6 by Neil S on August 13, 2019 - 9:20 am

    What did you think of Muller’s Physics for Future Presidents?

  6. #7 by Scott Schmidt on August 23, 2019 - 4:41 pm

    I remember those dotcom days well. Everyone was asleep in the same dream. Investors, especially angels, have grown up a lot since then but there’s still a large amount of arrogance in the field.

  7. #8 by Ted Christian on February 7, 2023 - 6:52 pm

    “Their (Solyndra’s) tech was bullshit.” Thanks, I was starting to think I was the only person who knew this, though reading about it back in the day it slapped me in the face within seconds. I was about to give up googling this in search of sanity when I finally typed in “Solyndra” and “bullshit”, all the more discreet descriptors having failed to find anyone who understood basic physics. Now I know there are at least two of us. Now I’m going to search your site and see if there’s a post about how a free floating Chinese balloon without a propulsion system can’t be maneuvered to and hover over a particular military installation, because I seem to be the only person who knows that’s impossible.

  8. #9 by Ted Christian on February 7, 2023 - 7:01 pm

    “Their (Solyndra’s) tech was bullshit.” Thanks, I was starting to think I was the only person who knew this, though reading about it back in the day it slapped me in the face within seconds. I was about to give up googling this in search of sanity when I finally typed in “Solyndra” and “bullshit”, all the more discreet descriptors having failed to find anyone anywhere with a grasp of basic physics. Now I know there are at least two of us. Next I’m going to search your site to see if there’s a post about how a free floating Chinese balloon without a propulsion system can’t maneuver to and hover above a particular military installation, because I seem to be the only person who knows that’s impossible. I actually saw mention of the thing being steered with a rudder. It all makes me think I should become a con artist, because it’s apparently really easy.

  9. #10 by Ted Christian on February 7, 2023 - 7:08 pm

    OK well I thought the first post failed because I had “work offline” checked in my browser so I typed it in again, along with another couple of sentences. And I notice you don’t seem to have posted anything on the Chinese balloon so that’s my suggestion for your next blog entry. There’s some good imagery on the hardware and I’d be interested in your take.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: