Insights by Danielle Fong

notes from a girl from the future

Category: Uncategorized


noun, aeronautics
an adjustable tab or airfoil attached to a control surface, used to trim an aircraft in flight.
in other words,
a rudder for a rudder too large to be turned directly.
a lever to move a larger lever,
a leader capable of lead otherwise stubborn leaders to action

Also, an open letter to the Canadian government, in advance of the global climate meeting COP21, on the part that we at LightSail are trying to play.

Trimtab v1

LightSail’s Danielle Fong on the Most Exciting Science

As 2013 was winding down, James Temple of Re/Code asked me about the most exciting science of the past year. That article is available here.

It’s hard to pin down exactly one “breakthrough.” The paradigmatic examples are in fact not what they seem.

For example, Alexander Fleming isn’t even the first one to have discovered or written about antibiotic properties of penicillin (as early as the 1870s the mould was written about). He was in a position to look for antibiotics, given his work on antibacterials during the war. And he made the initial discovery in 1928, abandoned clinical work on it in 1931, restarted in 1934, and continued to try to get a chemist to purify it until the 1940s. The development of antibiotics was not just one thing.

For that matter, the lightbulb was a filament, plus a vacuum, plus a high resistance, plus a whole electrical system — generator, mains, feeders, the works. Bulbs existed before Edison, but he brought a system forth to provide lighting.

And the Wright Brothers weren’t the first ones to have achieved flight, but heavier than air (Zeppelins were first) *controlled* flight. They needed to invent new flying paradigms, wing warping, new engines, new propellors, control systems, developed elevators and wings. They tested in wind tunnels, an invention of their own. It wasn’t just one thing — though there certainly was a moment of truth in the air!

Hence, themes. My two picks for the most exciting things in science last year:

1) Exoplanets! – so many worlds teeming with life, all in the sky, perhaps within reach.

So much happened this year. We are in a galaxy with perhaps 100 billion worlds, 17 billion “earth like.” The galaxy may be a fertile garden of life.

What’s driving all of this is an incredible refinement of the transit technique for the detection of exoplanets, culminating in the Kepler spacecraft.

Researchers are really finding their stride in data analysis and techniques, and a plethora of discoveries have resulted.

These discoveries have helped make it possible to imagine humanity spread throughout the stars, and innumerable worlds, and lifeforms abound, waiting to be discovered.

2) How Genes Really Work

Specifically, steadily increasing control and understanding. Take a look at how many of these advances listed here involve epigenetics or gene therapy or the discovery of an important gene or the sequencing of a new species or the use of genetic modification to understand a new organism.

We’re still only scratching the surface here. But genetics isn’t like computer code; it’s chemistry and systems science and ecology. Genes are regulated by the environment, and other genes, and genes regulate the environment in turn. We’re understanding more and more how to introduce genes into new lifeforms, how they’re expressed, regulated, how they mutate, change, how they fold (we caught a ribosome in mid fold!).

We can now even make machines — it is a stretch to call them robots — but machines, nanomachines, out of DNA. (See video below.)

I’m both excited and disappointed with my two picks. They give us amazing new capabilities — dreamt of for a long time, now made real. But they are not the broad new continents of possibility that some hope for in breakthroughs.

Personally, I think that at least one of three things I’ve been working on in 2013 should be on there, eventually. In the future, perhaps, on whatever Wikipedia page you’d read, you’d read that I came up with the idea in 2013. But since none of it is public, and none of it has been proven yet, you’ll only hear about it in a few years, and if LightSail is any indication, it will be another three years before anyone writes about it as a breakthrough, and another three until it is actually real.

A case for immortality in a finite universe

Some futurists and bioethicists, argue that, on a planet with finite resources, prudence dictates that immortality is not to be aspired to — that the resources used by a life lives by the old might only displace the possibility of a life lived by the young. I think that this is a pessimistic view; one that does not allow for the grandest of possibilities.


The 2012 Hubble eXtreme Deep Field

An immortal race is one that can dream of spreading throughout the stars. There are 5 billion billion planets in the goldilocks zone, potentially capable of life, more than the total number of cells on Earth.

Any of these could serve as a lifeboat, were a catastrophe to occur in our other homes. The story of civilization, and the only light of consciousness that we know exists in the universe would continue to live, would flower and spread and thrive.

An immortal race is one for whom planetary constraints are personal constraints. The choices you make echo throughout eternity — and you see it. Would an immortal person retire to a soon-to-be underwater Florida and care on with their planet warming ways? In just the same way that declining child mortality rates and other markers of wealth reduce the urge to rapidly reproduce in early adulthood, would an immortal race also give more thought and tender care for their lives, environment, community? One would have the time.

An immortal race would be wiser. Not all of them, surely; but those who throughout the centuries have guided us well, towards health, safety and greatness, will naturally form networks and communities and be respected in their life and judgment and rule. That which can only be learned through experience will be deep in their bones; the boon of their wisdom would be available for all around them, not subject to decline, embrittlement, and decay. The old founders and masters of organizations and disciplines would stay with us, providing not only
the old precepts, but the old questions, the old intents, and the new views in response to a new world.

How different would the republic be, were Plato to have stayed with us?

The change of society with respect to critical technological changes is always underestimated. Look at how strongly fertility rates decline as life expectancy rises!

(correlation does not equal causation, but surely something *is* going on here. Were I in a traditional society, at 13 I might have already been pressured to bear children. I am currently twice that age, and do not even yet feel pressured to make a family. I feel that I have the time to build the world I want to bring children into)

From another perspective, suppose the default was immortality. Faced with resource constraints, would we *choose* to let some members of the population get sick and die just to apprehend their resources? Wouldn’t to do so seem barbaric? Necessary — possibly — but only considerable as a very last resort!

Finally, an unaging race is not invincible. We are still at risk crossing the road.

“It has become, in my view, a bit too trendy to regard the acceptance of death as something tantamount to intrinsic dignity. Of course I agree with the preacher of Ecclesiastes that there is a time to love and a time to die – and when my skein runs out I hope to face the end calmly and in my own way. For most situations, however, I prefer the more martial view that death is the ultimate enemy – and I find nothing reproachable in those who rage mightily against the dying of the light.”

Stephen Jay Gould 

As we may discover…


Vannevar Bush, with the first modern analog computer

“The National Research Foundation should <be> free from the obligation to place its contracts for research through advertising for bids. This is particularly so since the measure of a successful research contract lies not in the dollar cost but in the qualitative and quantitative contribution which is made to our knowledge. The extent of this contribution in turn depends on the creative spirit and talent which can be brought to bear within a research laboratory. The National Research Foundation must, therefore, be free to place its research contracts or grants not only with those institutions which have a demonstrated research capacity but also with other institutions whose latent talent or creative atmosphere affords promise of research success.”

Vannevar BushScience, the Endless Frontier (1945)

Vannevar Bush took over the National Advisory Committee for Aeronautics in 1938. The period from then until the Mansfield Amendment of 1973 (which turned ARPA into DARPA) was probably the most productive and efficient period for government sponsored research in history.

The competitive bid process, centralizing research in the universities and national labs, came later. I conjecture that, dollar for dollar, this process is 100x less effective than the old ARPA and National Defense Research Committee approach of finding and funding nascent research where and how it is ready to be done.

Also, even if historically it’s been difficult to predict, a few people have been all-stars. Vannevar Bush is one, as was Von Neumann, J.P. Morgan (who was a one man Silicon Valley, funding Edison, Ford, Tesla), Thomas Edison (who employed both the young Tesla and Ford!), Marvin Minsky, Stewart Brand, Ernest Rutherford, Arnold Sommerfeld, Neils Bohr, Steve Jobs, Bob Taylor, J. C. R. Licklider, J.R. Oppenheimer, etc.

Even in the modern era, where a billion dollar software company is a “unicorn”, showing up only once in 1,538 VC funded startups, some pick them time and time again. (like Keith Rabois, who has personally funded 8 of the 36 since 2003 — Square, Airbnb, LinkedIn, Yelp. Palantir, Youtube, LendingClub, Yammer.)…/11/02/welcome-to-the-unicorn-club/

The modern, largely faceless NSF doesn’t give the authority for a modern Bob Taylor to pick researchers and research projects with anything like the facility that Keith has been able to pick his own investments. Time for a change

(hat-tip to David Dalrymple and  Katriona Guthrie-Honea)

A Principled Revolutionary

Laura Schewel, someone who has been a personal inspiration to me, and who has been an amazing friend, has been named by MIT Technology Review as one of the world’s top 35 innovators under 35. She’s accepting her award at this year’s emTech, and I wanted to write here a short letter about the importance of her work, and what it means to me.


Laura Schewel

Cites have been called the defining technology of civilization.They are emergent phenomenon, work admirably at an extraordinary range of scales and complexities, incubate our most audacious dreams, are more resilient and long lived than even the hardiest identified organisms, and are on balance, the most scalable, efficient, general purpose mode of human organization that we’ve got. Cities are green, and cities are our future.

Yet for all of their merits, the dynamics of cities remain much a mystery. And traffic, among the most dynamic of  dynamics, is among the most consequential.

Access defines neighborhoods and the life of commercial enterprises. And at the city level, we give up a spectacular amount of our cities to pavement and automobile traffic (estimates vary between 30 – 40% of our cities and 50 – 60% of the world’s built surface). The road network layouts of cities are incredibly durable, withstanding fires, earthquakes, floods, the replacement of the entire building stock, even the fall of a civilization.‡ ⩈

City managers want to know which roads will help their city cope. Real estate developers desire what will help their developments grow. Retail establishments want to know who visits where, when, how, and for what. Environmentalists want to know how to shorten and make efficient shopping trips and daily commutes. And citizens want to know why so many transportation improvement projects seem to harm their commute, rather than help.

The questions drive a multi-billion dollar intelligence industry; people are paying for answers, and customers are sophisticated. Fundamentally, however, the field is in a pre-Galilean state of knowledge — flows, impressions, anecdotes, and theories abound, but this there hasn’t been enough data, at a granular enough level, to create and verify models that provide meaningful efforts to specific questions. Guesswork, and linear projection predominate. We can do better.

Laura Schewel is a principled revolutionary. Her extreme bias is to uncover hidden efficiencies in planetary scale infrastructure; work that is among the most pragmatic and impactful that I could imagine. And so, her and her StreetLight Data team combine precise and granular data, gathered by GPS with fleet vehicle and opt-in insurance partnerships, with scientific rigor, world class modeling and simulation, high octane data visualization and analysis, and deep insight in systems thinking and dynamics. They use these tools to provide real answers to specific questions for specific projects for governments, retailers, real estate developers, car dealerships, and economists. Moreover, they provide the tools, perspective, and cognitive framework for each of these customers to play with, learn from, and get a feel for the dynamics of each of their respective systems. StreetLight Data is bringing excellence in systems thinking to our most important organizations.

My cofounder and I have at this point met a large fraction of the strikingly competent beings that comprise the technology elite. Struck by the discrepancy between the ability of startup companies and governments to act, we asked ourselves, who among our friends could we imagine as president, leading our government to ascendance, success and efficiency?

We thought for just a second, and then at once said, “Laura Schewel.”

– Jane Jacobs, The Economy of Cities, 1970

– Stewart Brand, How Buildings Learn, 1995,
– The 1460 Aztec plat of Tenochititlan defined the principal streets of modern central Mexico City.) Alvarez, Jose Rogelio (2000). “Mexico, Ciudad de”. Enciclopedia de Mexico (in Spanish) 9. Encyclopædia Britannica. pp. 5242–5260.

A Brief Note on Thermodynamics

One of these days, I’ll try to write up the rules of thermodynamics so that people stop getting mislead. This is not a particularly well edited essay, but it should go up somewhere. Apparently there was a considerable armchair debate about what we are trying to do at LightSail on Rebuttal below:

Ok, I’ll bite.

First of all if you’re actually looking for rebuttals, it’s usually easier if you post it to my email or some website I own (e.g. and have notifications for. We get an awful lot of media coverage and I don’t monitor everything.

Second, the efficiency we’re targeting is 70%. Not 91%. I don’t know where people got that from. We include all of the practical losses that people have mentioned — motor inefficiency (at our scale, typically 5% loss, not 10%, as some people seem to believe — it depends upon scale), friction, heat loss through our insulated tanks, etc. We are not actually there yet. If our first product is between 60% – 70% efficient we’ll be pleased, but we’re determined to push that as high as we can.

Third, it appears you are under some confusion about thermodynamics.

It is a slippery field, and I don’t blame you: both Bill Gates and his advisors made similar mistakes the first time through.

a) We’re not doing isentropic compression or expansion. The whole point of the water spray technique is to approximate an isothermal compression and expansion cycle — the water absorbs heat from the air rapidly. The correct first order approximation is that the heat capacity of the *mixture* is effectively added to the heat capacity of the air. Try deriving this from the 1st law, starting from T_water = T_air, and following the derivation of adiabatic compression without heat exchange to the outside that you see in any thermodynamics text.

Actual results have our output ∆T < 20 C and maximum hotspot ∆T = 60 C. Water spray actually cools. It is surprising how controversial this has been in the 21st century…

b) You’re using Carnot efficiency in an erroneous way. Compression and expansion are only part of the cycle. While it’s true using the generated heat alone in a heat cycle would grant you the efficiencies you describe, this is irrelevant, because we’re not doing that. There’s a whole other thermodynamic resource: *the compressed air* that this is wasting. So we’re not doing that.

Here’s an illustrative exercise.

A Carnot Cycle is perfectly reversible: run the cycle backwards, and 100% of the heat turns back into mechanical energy. How is this possible, one might ask, while at the same time being compatible with Carnot efficiency?

Several reasons: as a heat pump, the Carnot cycle turn W units of work into 1/(1 – Tc/Th) units of Th heat! There’s more heat, in joules, pumped than work put in.

This might seem to violate intuitions, but you can purchase heat pumps at any hardware store. You will notice that there are heat pumps and refrigerators with a coefficient of performance much greater than 1 widely available. This really works.

Now, draw a T-S diagram of a Carnot cycle for an ideal gas. It’s a rectangle in T-S space, the isothermal compression and expansion processes are horizontal lines, and the adiabatic processes are vertical.

Shrink the adiabatic processes to nothing, so that isothermal compression and isothermal expansion are at the same temperature. No heat is moved, and there is no net work. It is still a reversible Carnot cycle. But it doesn’t seem to do anything.

Why would you do a thermodynamic cycle if you get no net work energy out?

Answer: if you get energy out at a *better time*!

If you get 100% of the energy out that you put in, but at a different time, then this is an *IDEAL* energy storage cycle. You can’t get more efficient than that!

However, by your mathematics, you’ll have a 0% efficient heat engine.

The thermodynamic equations for a full heat cycle are *different* than for an energy storage cycle. You cannot just use them blindly. You have to go back to the first principles: the first and second law. (which, by the way, are never violated here — there is never entropy destruction in this or any other ideal reversible cycle).

All this said, this is an idealization. In fact there are losses in the process. Friction, for example. Resistance in our motor coils. Air turbulence running through valves. All this goes to heat.

What we do with this heat is that we collect it so that we expand air at as high a temperature as we can.

We don’t get as much energy out as if the energy never went to heat, but it is a small boost if we can get it. About 10% relative energy storage efficiency (E_out/E_in) for a 30 C heat increase if we’ve got it, nothing to sneeze at.

But even if we lose 100% of the extra heat, and have to expand at ambient temperature, our efficiency only goes down by that same 10% relative efficiency. It is not bad.

Also, it’s not so hard to insulate a large tank.

In general, while I applaud the efforts of people to work out things for themselves, you have to be extra careful that you’re not deluding yourself. It is worse to take a well known equation, misapply it, and declare impossibility, than it is to say that you heard about something but haven’t worked to complete understanding from the fundamentals yet.

It’s not actually working something from first principles if you get them wrong…


Danielle Fong
LightSail Energy


Defusing the Carbon Bomb

This article first appeared in issue n.16 of Oxygen, sponsored by the Italian energy giant Enel

The powerplants we are building now will define the biosphere of our planet for the next 5000 years.

The math is straightforward, and stark. Carbon dioxide stays in the atmosphere for a long, long time. It takes nearly 5000 years for limestone and rain to scrub the atmosphere of carbon down to plausibly manageable concentrations. It takes half a million years for igneous rock to scrub the atmosphere down to more temperate concentrations.

A coal plant, built today, has an expected lifetime of 50 years or more. Every year, a 1 GW coal plant throws 8 million tons of CO2 into the atmosphere — more than the mass of the Great Pyramid of Giza.

It gets worse. There are roughly the equivalent of a thousand 1 GW coal plants in service today. Collectively, in a decade, they blast 80 billion tons (10 ppm) of CO2 into the atmosphere — approximately the weight of every single living thing on earth. Business as usual for coal plants would make more of a carbon impact that a firestorm burning every living thing on the planet.

We cannot assume that nature will just take care of this mess.

In the past 20 years, electricity generation worldwide doubled. In the next 20 years, it will double again. If we build those plants the way we have been building them, and run them for the 50 years we expect them to last, we will nearly double the amount of carbon dioxide in the atmosphere from when, at 275 ppm, civilization emerged, to 500 ppm, and beyond.

Some policy makers say that reaching 450 ppm would be stable for the Earth. Some scientists ( fear that 350 ppm — much less than the current 396 ppm, is necessary. But as our climate models are making clearer and clearer, blasting to 500 ppm and beyond is not safe territory.

Where that leaves us?

We need more than a faith-based strategy. We need to ask ourselves, what does this mean for us?

For the past many hundreds of millions of years, there have been three major earth climates.

There’s hot earth — greenhouse earth. Ice thaws, and organic matter rots, releasing methane, a potent greenhouse gas, and CO2. Oceans stratify, building hot, nutrient poor layers of water atop the oceans, preventing oxygen from reaching the layers below. Ocean life dies off rapidly, and the focus of life escapes to land. Temperate regions become vast, arid landscapes, and fires and megastorms spread throughout the landmass.

There’s cold earth — icehouse earth. Glaciers blanket and mould the landscape, reflect the sun, and cool the land. Life, crowded out of the land, find its greatest vitality on the sea shelf. Oceans recede — land bridges emerge. Megafauna dot the continents. In the colder periods, the imposing glaciers grow and dominate; in the warmer periods, environmental niches for life open up, for upward new species, like mankind.

We humans emerged in a warmer period of an icehouse earth. We spilled out and filled the alluvial plains of every corner of this planet, built towns, and roads, and cities, covering 3% of the planet surface, and engineered the biosphere, consuming a quarter of its output, disrupting three quarter of the fertile land, and 90% of the biosphere, growing and replicating until we, and our livestock, and our pets, collectively outweigh wild nature, land and air animals, by 50 to 1.

Which brings us to now.

This third era, the anthropocene — the manmade epoch, is without precedent. We would have had another ice age, had humans not intervened. The atmospheric record and the climate tracks the technological and social development of civilization for more than a thousand years. We consume more energy than the tides and waves could ever supply — co-opt more water than our aquifers can sustain, consume more of the food chain directly than any other thing species. We are a force of nature; rivaled, perhaps, only by the powers of the sun, wind, earth, ocean and time.

Scientists fear that our climate is moving away from its zone of temperate stability; the nice, comfortable climate to which we have been adapted. Fish swim in the ocean. Tropical diseases are contained. Tropical agriculture is possible — megadroughts and ultrafloods and superfires are avoided.

Business as usual is now heading towards greenhouse earth. Unless we do something, and do something quickly, unless we face these problems, invent solutions, and scale them up faster, in an absolute sense, than any industry has ever scaled up before, then we will live in that greenhouse earth. What will it really feel like? Maybe we’ll adapt. Life will survive; much of the planet’s history is of a greenhouse earth. But one thing is for certain. We won’t find comfort easily. Greenhouse earth is for crocodiles.

Human beings must realize that we are now in the driver’s seat. We need to know where were going, and we need to talk about where we want to go, and we ask ourselves if we have the courage to turn the wheel.

Climate Change Skeptics

I don’t understand the reasoning of so many ‘climate change skeptics.’

Let’s imagine the climate in question is not Earth’s, for a moment, and is instead the climate of a black box, hovering in a vacuum, with a big lightbulb shining next to it. Practically all its energy comes from the lightbulb (the rest from the residual heat within, and some dim source of central power), and practically all of its cooling consists in radiating infrared back outward. On the surface of this box tiny microbes are busy manufacturing and installing a layer of glass, which infrared cannot penetrate, covering it. We now wait, and see what happens.

The infrared is significantly absorbed by the glass, largely radiated back to the box, and thus the largest channel for cooling — essentially the only one capable of sustained cooling in the long term — has been attenuated.

Now replace the black box by Earth, the lightbulb by the sun, and the glass by CO2.

One would imagine the black box to have very strange properties were it not to heat at all. It might, for some time, somehow redirect some of the heat into less observable sections of its mass (e.g. the lower levels of the Earth’s oceans, which have a much greater heat capacity than its atmosphere). Yet this cannot last forever: there is only so much ocean. It might also become more reflective, absorbing less light (e.g. the earth’s clouds, desertification)? Yet an opposite effect comes from the melting snows and ice caps and constructed asphalt we add in urban areas: all of which have radiance and albedos observable from the outside (e.g. our satellites). Finally, the black box radiation is proportional to the fourth power of the temperature, so even if the percentage of radiated power that reaches the outside of the glass is diminished, if the temperature of the primary radiative bodies becomes less even, such that ∫T(new)^4 dA >> ∫T(old)^4 dA, the temperature can stay roughly constant. Other than that, there’s close to nothing that can be done: that box will very probably rise in temperature, and almost certainly the climate will change.

Skeptics correctly points out that the lightbulb varies in power output. And the black box is moving a bit relative to the light — further away or closer by — shinier or cooler or more black parts facing the light at any given time. They also point out that the glass isn’t the only thing surrounding the black box — for example they have noticed also a shiny layer of dust on the glass (aerosols), and an even bigger layer of glass underneath the glass we’d place (water vapor). And they point out that the layer of black paint appears to be, in a great proportion, liquid, and with a high heat capacity, and churning cyclically, and that there’s a lot of it, so that in any one instance a cooler or a warmer parcel of that liquid is showing.

None of this changes a thing about the fact that if we put yet another layer of glass on the box, the smart money is on it heating, and certainly on it changing. How could it not? At this point the onus is on these climate change skeptics to suggest a means by which the box is supposed to stay exactly the same.

Which brings up an interesting point. Maybe it is not so necessary that the Earth stays the same. Maybe there are credible arguments that explain that, really, the box won’t change that much, and for the teeming, glass manufacturing cultures of microbes living under the glass that these changes are not really such a big deal.

Some scientists, who I respect very much — Freeman Dyson for example, make this very argument. I respectfully disagree with him, as I think that there’s far too much risk in disrupting the biosphere, and that the disruption, famine, and loss of ecosystems and species that have already occurred are too great a price to pay, that oil wars, tyrannies, and people dying of respiratory illness from coal plants aren’t exactly positive either, and estimates of the probability of some catastrophic event happening, like say, Greenland melting, the consequences of which are too dire to imagine, range somewhere between 10% and 80%.

But that’s a philosophical disagreement. One might say that instead of engaging in ‘climate change’ skepticism, Dyson and others are engaging in ‘climate problem’ skepticism.

Too often, what we have with ‘skeptics’ is a scientific disagreement: the great majority say either that it is happening, but only as part of natural variation, and they had nothing to do with it, or that it isn’t happening at all. Which, at this point, seem more like the antics of a child screaming ‘I didn’t do it,’ or putting their hands to their ears, singing ‘la la la, I can’t hear you!’ than of a calm and reasoned scientist — or skeptic — examining the assumptions of a majority opinion. Their conclusions are already drawn.


For those already sold on the problem, my startup, LightSail Energy, Inc. is an exciting, well-funded startup in the $100 billion field of green tech energy storage. We are located in Oakland, California. We are seeking to fill several Mechanical Engineering positions. Applicants should have at least 5 years experience in product design of mechanical components.

Please be familiar with at least some of the following:

engine design, fluid dynamics (analytical, experimental, computational), heat transfer, thermodynamics, fluid power, pistons and seals, and multiphase phenomena.

Candidates should be comfortable with 100 kilowatt to multi-megawatt systems. Our needs range from mathematical modeling and design of experimental apparatus during the Research and Development phase, to designing for manufacturability and reliability. The ideal candidate will be a hands-on design engineer who possesses a high level of creativity and innovation required to be a valuable asset to the company.

Interested? Please send your resume to