Some people use echolocation to get around

Link to article

From KTH Royal Society of Technology

Blind people cannot see, but that comes in varying degrees. Only about 18% of people who are legally blind see nothing at all, only darkness. To get around, most use a cane pointed and waved in front of them to detect objects, steps, and holes. Only about 2-5% of blind people have guide dogs, mostly because of their cost (food, veterinary care, and supplies), need to care for the dog, and lack of actual need to move around.

Various technologies exist to help blind (or sight-impaired, if you wish to be accurate) people to navigate in their daily lives. They can range from tens to thousands of dollars.

• Smartphone apps like BlindSquare cost $40-60.
• A new strap around your arm called the WayBand costs $179.
• Handheld or wearable computer devices like StellarTrek, Glidance, and the Biped Vest can run from $1,000 to $1,500 to $2,000-3,000, respectively.
• Smart glasses and visors are the most expensive at $4,000 for  OrCam MyEye Pro and $7,000 for eSight 4.

Some blind people rely on echoes from taps of their cane or stomping feet to get a relative position of objects. But other than the standard white cane, some people rely on themselves using sound that they make with their mouths in a process called echolocation. Basically, like a bat or dolphin, echolocation involves sending out a clicking sound and interpreting the echo it makes. It helps judge size, position, shape, and even texture of objects in front or to the sides.

Here is a video showing Daniel Kish (President of the World Access for the Blind) demonstrating this and explaining aspects of human echolocation.

From YouTube

The first report of blind people with higher level abilities in hearing was published in 1749 by Denis Diderot, who was a philosopher, art critic, and writer. He also co-created a general encyclopedia in France in 1751. Some of his writing was on science topics, and he compiled them in a collection called Memoires sur differents sujets de mathematique (1748). In it, he wrote about mathematics, physics, and natural philosophy, and he was very interested in acoustics, the branch of physics that studies sound. Some of his essays in the 1748 work dealt with original ideas on acoustics, tension, and air resistance. He had a blind friend who could sense objects in front of him as well as the distance from him. Diderot thought this was due to what he called "facial vision" or "obstacle sense", caused by increased sensitivity of the facial nerves and end-organs to pressure on the face.

Denis Diderot (Wikipedia)

From 1808 to 1874, various researchers experimented with blind people and came up with many ideas about how they could tell objects were near. An Austrian psychologist Theodor Heller concluded from his tests that his subjects could perceive objects by sound at about 3-4 meters and by air pressure on the forehead at about 60-70 cm. 

Researchers at the Smith-Kettlewell Eye Research Institute in San Francisco recently conducted a study to learn more about how this works. They worked with 4 male blind people who were already experts in practicing echolocation, and with 21 people who could see (12 male, 9 female) and were not trained in echolocation.

They were placed in a dark booth and wore a special cap with 64 sensors to detect their brain activity. They also wore earphones to hear computer-generated fake clicks like the human mouth would make from experts in echolocation. 

A type of sensor cap like the one used in the study (BioSemi)

The first simulated click was fed into their earphones as if they had made the sound themselves and projected it in front of them. A second click was computer generated to sound like it had reflected off something at different angles (5°, 10°, 15°, 20°, or 25°) to their left or right. The clicks were produced in different numbers, a set of 2 clicks, or 5, 8, or 11.

Top view showing the left/right angles of simulated clicks (Garcia-Lazaro & Teng, 2026)

It should be no surprise to learn that the expert echolocators in this study performed better. From the brain activity sensors, the researchers determined that because of their experience in the past, their brains could process the clicks better than brains of sighted people doing this for the first time. Their processing was more sophisticated:

• they put together multiple clicks into a direction 
• sighted people took each click/echo separately to make individual judgments of the location

People who use echolocation can also judge the size of objects, and sighted people can learn to tell the difference. California researchers Teng and Whitney set up 2 circular plates of different sizes in front of people in a dark room. The larger plate was sometimes on top, sometimes on the bottom. The angle of the top disk (θ) was also changed from 4º to 37º by raising the top disk. The test subjects made clicks with their mouths and reported on the location of the larger disk.

Setup: left shows what the test subjects faced in the dark, right shows a side view (Teng & Whitney, 2011)

These sighted people began to learn how to judge the location in 1-2 hours of testing, and by 3-6 hours they had reached their maximum ability. Some of them were almost the same ability as expert blind people who had experience using echolocation.

In another test, the 2 disks were the same size, and the object was to tell whether the top disk was to the left or right. That left-right angle from the test subject's head varied from 1.1°, 2.2°, 4.4°, 6.6°, and 13.2°. This was more difficult, and the average score was 63.5% correct even at the largest left-right angle of 13.2°. But some people were 95% correct at that angle. Two out of 11 people were able to judge as small an angle as 4.1° and 6.7°.

Diagram of setup to determine left-right position (from Smith-Kettlewell Eye Research Institute)

In 2021, researchers tested sighted volunteers against blind echolocation experts and novices. They faced a rectangular plate which was rotated to 4 positions. So, they could get 25% correct just by random guessing. The idea was to see how well they could judge the "shape" (by a different angle).

Setup for the rectangular plate experiment (Norman et al., 2021)

Sighted people and blind novices were trained in echolocation 2-3 hours a day, twice a week, for 10 weeks. The rate of learning of sighted and blind novices was the same, and their accuracy was also not different statistically. They got 38% to 69% correct from training period 1 to 20. If you separate the data, the sighted subjects got 76% by session 20, while the blind novices scored an average of 62%. By week 10, both novice groups were as good as the expert blind echolocators who were being tested at a further distance!

Researchers in the UK created virtual mazes for people to navigate in 2020. First, they made a real maze in different configurations but on a smaller scale than for people. Next, they put a mannequin head at different places and angles inside the mazes and generated a click from its mouth. That sound was recorded and used in the virtual maze when people heard the sounds on their earphones. Third, the participants listened to the sounds and imagined they were in a maze; they then used a keyboard to "move" themselves through the mazes based on the different sounds they heard. The final target sound had a different sound than the rest of the maze, so they knew when they had reached the end.

Three configurations of virtual mazes. Each square represents a computer key move

(modified from Dodsworth et al., 2020)

This study was done in 2020 using blindfolded sighted people, and in 2021 using blindfolded sighted people, blind novices, and expert blind echolocators. In 2020, the test subjects learned how to use the virtual echolocation to navigate through the mazes faster and with fewer "virtual collisions" with the "virtual walls" of the mazes. They had a 98% success rate after 14 training sessions. And, after 19 and 20 sessions, they were given mirror images of the mazes and succeeded at a similar rate.

In the 2021 study, blind and sighted novices became as good as expert echolocators after 14 sessions, and the sighted people ran the mazes faster than the experts (40.87 seconds, compared with 67.49 seconds). Some say that's because they weren't as afraid to bump into walls, even virtual ones, as the real blind people.

When people perform echolocation, what is being activated in the brain? Obviously, they hear the echoes of clicks, but many factors are involved in processing the information. It could be direction, size, even texture of what they hear. Mapping the brain can be done to see where it is active during different stimuli. This image shows generally where certain feelings are sensed. Vision is interpreted in the rear of the brain, while hearing is interpreted on the left and right sides. In the lower picture, you can see that there is some crossover (purple area) between the two senses.

From Science Photo Library

From Society of Neuroscience Graduate Students

A group of scientists compared 2 blind patients with sighted controls. They first allowed them to hear environmental noises (like wind, leaves rustling on trees) when the blind people made echolocation sounds. Both could detect objects, but the one that had been blind since 13 months old had more brain activity than one who had been blind since 14 years old. A sighted control showed no activity when they tried to identify objects that the blind people were echolocating.

When they removed all background noise and let them hear only the echolocation clicks and echoes, the blind people's brain activity was focused almost completely on the visual part of the brain as they tried to determine what the objects were. Controls again showed nothing.

Images from Thaler et al. 2011

So, anyone can learn to echolocate, and science is learning more about how it works. Here is another video with Daniel Kish not only explaining more about his use of echolocation, but demonstrating how it allows him to ride a bicycle and even travel.

Video from YouTube

Whale pee is an ocean bounty 

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Most people would easily agree that peeing in a swimming pool is unsanitary. But people think nothing of swimming in lakes, rivers, and oceans, where many animal species do that (and more). Pee (urine) is a bodily waste product, something the body doesn't need anymore and that can cause problems if retained. But it can also be useful in environmental settings.

Whales are the largest animal creature in the seas and world. The fin whale, second largest in the world at 18–27 m (60–90 ft) long, can put 946 liters (250 gallons) of pee into the ocean in a single day. The third largest whale, the sei whale (19.5 m or 64 ft long) excretes 522 liters (138 gallons) per day. 

A fin whale and comparison to a human in size (Wikipedia)

A sei whale compared to human (Azores whale watching)

The ocean is far larger than any swimming pool, so you might think even this much urine is still a drop in the bucket. You'd be correct. Estimates put the population of sei whales at 50,000-80,000, and fin whales comprise about 100,000-119,000. Compare that volumetric contribution of urine to the 321 million cubic miles of ocean water.

Researchers from the UK and US have learned that gray, humpback, and right whales do not eat or defecate during their breeding season, but they still urinate. For example, in summer humpback whales feed along the shores of the Alaskan coast, but in winter they travel to warmer waters near Hawaii to breed. They have accumulated thick layers of fat (blubber) in summer, and as it is digested in the winter breeding season, the blubber is broken down into urine. A key chemical component of urine is the nitrogen-rich urea.

Location of humpbacks during feeding and breeding seasons (Science News Explores)

Professor Joe Roman (University of Vermont) and his colleagues from Arizona, California, Florida, New Jersey, the UK, Brazil, and Denmark published a study in March 2025 regarding how baleen whales transport nutrients from their feeding grounds to tropical and subtropical ecosystems where they breed. Ocean creatures like zooplankton float in the waters as the currents take them wherever they drift.

Types of zooplankton (Wikipedia):

copepods (1–5), gastropod larva (6) doliolids (7), fish eggs (8), and decapod larva (9)

Their wastes and dead bodies fall slowly from all levels of the ocean to the seafloor in what is called marine snow.

From YouTube

But whales feed mostly on the bottom, so the nutrients there get recycled only when whales come to the surface to pee or poop. It may have something to do with the different pressure and temperature causing the body to release its waste. This process of bringing such elements to the surface is called the whale pump. 

 

The whale pump distribution of ocean bottom nutrients (Roman and McCarthy, 2010; Roman et al., 2014)

So, the nitrogen and phosphorus in whale wastes mix with the upper ocean layers and serve to feed zooplankton and other organisms. Roman and his colleagues studied baleen whales (gray, blue, humpback, and fin whales) to see how much they contribute to the ecosystem from their wastes, rotting carcasses, and ejected placenta. As mentioned earlier, they found that one fin whale alone can excrete 1,136 liters (250 gallons) of urine per day. “In a place like Hawaii, the whales are bringing in more nitrogen than is being transported by wind and currents,” Roman said. From urine, feces, rotting bodies, and placenta, those whales dump 3,784 tons of nitrogen and 46,512 tons of organic matter into their breeding grounds, and most of the nitrogen in it comes from the urine.

Humpback whale peeing (from YouTube)

Getting back to urea, the major component of urine,  it looks like this chemically. It has 2 ammonia groups attached to carbon and oxygen. 

From Wikipedia

While zooplankton are the animal portion of plankton, phytoplankton represent the microscopic plant portion. These absorb urea in ocean waters and break it down into ammonia and carbon dioxide, which are building blocks of amino acids and proteins. As phytoplankton and zooplankton feed and grow, they circulate in the ocean as marine snow, as well as serve as food sources for other sea creatures. So, whale urine fertilizes the ocean. And the blue-green algae component of phytoplankton is also important in absorbing carbon dioxide from the atmosphere, an element of climate change balance.

Phosphate ions are also in urine, and in greater amounts in feces, and the phosphorus in those ions are needed by the local plankton to make DNA, RNA, phospholipids in cell membranes, and ATP (an energy source for cells).  Here are examples of just how much of each is excreted relatively in whale feces, as well as other macronutrients.

Data from Freitas, et al., 2025

Whales do not find food and breeding grounds in the same places in the world, which is a good thing for spreading around their pee nutrients. Here is a map of just 3 species showing where they live.

Figure adapted from Roman et al., 2025

A 2015 study by Professor Christopher Doughty and his team (including Joe Roman) from various countries investigated the contribution of body wastes by whales and other animals over time. With regard to whales, they found that since whaling became an industry, the "whale pump" effects have dropped by about 70%, so fewer nutrients are now spread in the oceans.

Whale urine is not the only source of nitrogen for phytoplankton and zooplankton. Bacteria, physical mixing of sea bottom, decomposing sea life, and runoff of fertilizers from the land also add it to the oceans. But whales do contribute as "ecosystem engineers", even if it is only locally. Some scientists refer to their spreading of nutrients across the planet as a member of the circulatory system for the world.

Scientists find hidden world under one of the oldest trees

Link to article here

What do you expect to find under a tree? One obvious answer is roots, or a root system. Another would be soil. But what grows in that soil separately from the tree's roots? Insects? Worms? Fungi? Bacteria? Scientists in Chile have studied a particularly long-lived tree and found some interesting answers.

The Gran Abuelo ("great-grandfather") alerce in Chile (The Guardian).

The alerce (pronounced ah-LAIR-seh) is one of the oldest living plants on Earth. Known also as Patagonian cypress or its genus name Fitzroya, alerce trees are native to the Andes mountains of Chile and Argentina and to southern Chile. The largest is named Gran Abuelo or Alerce Milenia, >60 m (200 ft) tall, with a trunk diameter of 4.26 m (14.2 ft). Its tree rings have been counted to 3,622, which marks is currently accepted age, but Jonathan Barichivich thinks it may be 5,484 years old. Average sizes for alerce measure 40–60 m (130–200 ft) high, occasionally more than 70 m (230 ft), and up to 5 m (16 ft) in trunk diameter. Some alerce have been around for over 3,600 years, Compare this to the sequoia giant redwoods of California, which are 50–85 m (164–279 ft) high with trunk diameters ranging from 6 to 8 m (20–26 ft). The oldest one known is 3,200–3,266 years old.

Sequoia (left, worktolive.info) vs alerce (Fitzroya) (right, Wikipedia)

But age alone is not what makes the alerce trees interesting. A Dover, Delaware group of scientists recently took samples of the soil under several alerce to see what they could find. They belong to the charity group SPUN (Society for the Protection of Underground Networks). Its mission is to map certain "fungal communities and advocate for their protection". The special fungi are called mycorrhizal fungi.

These fungi produce tangled interconnected networks underground where they form symbiotic relationships with plants. That means the plants are dependent on them, and they are dependent on the plants.

Mycorrhizal fungi (right) living in soil and infiltrating roots (Hokkaido University)

Mycorrhizal fungi mixed in with roots (Ohio State University)

Four major groups of soil fungus can be found in the world: Zygomycota (<1,000 species, common bread molds), Ascomycota (30,000 species mostly yeasts used in baking), Basidiomycota (most mushrooms, toadstools, and puffballs, 40,000-52,000 species), and Deuteromycota (17,000–25,000, including the mycorrhizal fungi).

Most soil fungi serve an important ecological role: to decompose lignin and organic matter in soil. Lignin is the complex polymer found in cell walls of plants, about 30% of organic carbon on Earth. Only cellulose is more common. Lignin is in dead fallen trees and leaves that have died.

Leaf litter decomposition (Mycosphere)

Why is any of that important to trees?

The decomposed material is food for trees (and other life). Fungi living under trees attach themselves to roots. Not only do they supply nutrients from soil to the trees, but the trees give them nourishment like sugars that the tree cells make. It is said that 80-90% of all plants form symbiotic fungal relationships like this.

The SPUN team took soil samples from 3 locations near each tree, and then from 4 additional locations about 5 meters away from it. These inner samples 10 cm (~4 inches) deep were pooled, as were the outer ones. 

Soil probe/auger and mixing bucket (left); 

tip of auger showing how deep the sample was (Extension University of Missouri)

Dark circles show the samples near the tree trunk, as seen from above.

Triangles show the soil sample locations further away. (Biodiversity and Conservation article)

Pooled samples were then added to a special liquid solution containing ceramic or zirconia beads 0.1 mm to 0.7 mm diameter (like fine sand or the width of a human hair). These were then shaken vigorously so the beads would smash into the soil and any fungi in it. These impacts would then break open the fungal cells and release their DNA, which could be separated from the mixture and analyzed.

Diagram showing how beads (blue) would crash into fungal cells (large red) 

to release their contents (small red) (adapted from Molecular Biotechnology, 2023)

The researchers found 300 species of fungi under the oldest tree, not under any others that they sampled, and it was twice as many as any of the samples under other trees. That means even the younger trees still had about 150 species of fungi, but over time the older trees had developed a richer, more diverse community underground.

There are two types of mycorrhyzal fungi: the AM type which grow into the plant root cells, and the ECM type which only grow between root cells. Two different DNA databases had to be used to learn which fungi of these two types were in the samples. The MaarjAM database had DNA information for the AM mycorrhyzal fungi, and the UNITE database had DNA information for ECM mycorrhyzal fungi. The left bar graph below shows as trees age, the number of colors (different species of AM fungi) doesn't increase, but one type (brown bar species) does. On the other hand, for the right bar graph, the number of colors (number of ECM fungi species) increases as trees age. In each case, one type of fungus (represented by a pink or light green bar) is present more than others.

Graphs adapted from original article (Biodiversity and Conservation, 2023)

Basically, the diversity of the ECM mycorrhyzal fungi increases as trees age. So, larger trees somehow provide a better environment for more species of those fungi, and if they are cut down, that environment is lost and will take hundreds of years to recover.

The number and diversity of such fungi may change the entire soil ecosystem as follows:

• they suppress plant root diseases
• they also promote healthier plants by attacking plant pathogens with fungal enzymes
• they produce many vitamins which promote plant growth
• they can penetrate soil better than roots to reach trapped water and help trees in dry seasons

So, a more diverse ecosystem of fungi makes for stronger forests.

Here is a simple video (1 minute) explaining the dynamic relationship between mycorrhyzal fungi and tree root systems. https://www.youtube.com/watch?v=v88gbtKBTv4&t=68s 

From YouTube

Katharine Burr Blodgett, the invisible woman

Blodgett looking through nonreflecting glass (WHMT video)

We take for granted many things about daily life, what we see and what we don't see. Glass, especially windows, is usually transparent so that we can see through it, but reflective glare often makes that difficult or impossible. Non-reflective glass is coated glass with reflection control properties to reduce the reflection of light from the surface of the glass. Katharine Burr Blodgett was largely the person responsible for developing the means to coat glass in that way.

Blodgett was born on January 10, 1898 in in Schenectady, New York. Her father was killed by a burglar before she was born, though, and so she and her brother were raised by her mother. The family moved to France when she was 3, and she returned to New York for a year, traveled in Germany, and then made a final return to New York in 1912. They'd managed to travel so much because Katharine's father had been born into an old New England family with money.

Katharine as a child (Lost Women of Science)

As a result of traveling, she didn't begin school until she was 8, but she was reported to have started reading as early as two. Most of her schooling was in the exclusive private Rayson School in New York City, which provided a strong foundation in math and science. She started Bryn Mawr College (Philadelphia) at age 15 by winning the top matriculation scholarship for the states of New York, New Jersey, and Delaware based on test results. She was interested in math and physics and studied optics under Prof. James Barnes. Although she was studious, she also took part in several sports, the Christian Association, and the Science Club.

Dalton Hall, the science and mathematics building at Bryn Mawr, 1912 (ACS Publications)

Katharine's graduation class of 1917 at Bryn Mawr College (Lost Women of Science)

Just before graduating in 1917, she took a tour of the research laboratory of the General Electric company in Schenectady perhaps to see what it might hold in the way of job opportunities. GE had been created in 1892 as a merger between Thomas Edison's companies and the Thomson-Houston Electric Company. Coincidentally, Katharine's father had been a patent attorney, first for the U.S. Patent Office, and then for Thomson-Houston, and finally for GE in 1893. Katharine's tour guide was Irving Langmuir, a brilliant scientist who had joined GE in 1909 and was associate director. He encouraged her to expand her education if she wanted to apply for work at GE. 

After graduating magna cum laude and second in her class at Bryn Mawr with a degree in physics, Katharine decided to get a master's degree. She moved to the University of Chicago in the fall of 1917 to study for the degree in physics. America had been in World War I since April of 1917, and her advisor William Draper Harkins had her working with another chemist Harvey Brace Lemon on the war-related issue of improving gas mask efficacy. The key for the work centered on how gases stick (adsorb) to the surface of activated charcoal (specially heated carbon with increased surface area due to the creation of pores). That work in surface chemistry later helped engineers develop better gas masks for the war as Germans developed more types of poison gas.

Activated charcoal.

Top left image (Wikipedia)

Bottom left image (1.1mm x 0.7mm) (Wikipedia)

Right images (Serafin & Dziejarski, 2023) showing pores (top) and chemical sites that adsorb various chemicals

Small box gas mask from World War I with activated charcoal canister and carrycase

(Roads to the Great War)

With the master's under her belt, Katharine was then able to land a job at GE, as the first woman scientist there. She worked with Langmuir on surface chemistry topics. Previously, Langmuir had been studying aspects of thin layers of molecules that were deposited on filaments of electric light bulbs. So, at first, Katharine was tasked with finding ways to improve tungsten filaments in incandescent lamps. 

Blodgett at work in 1920 at GE (ACS Publications)

During that time, she proved herself to be invaluable, both at GE and in collaborative work elsewhere, like the University of Chicago and Bell Laboratories. Researchers relied on her to interpret data or devise experimental protocols, but she was not listed as a coauthor on their papers.

Six years later in 1924, Langmuir encouraged her to get a doctoral degree, and she did just that at the Cavendish Laboratory of the University of Cambridge. Langmuir knew Ernest Rutherford there, and he convinced the 1908 Nobel Prize winner to take her on. He probably knew that despite the poor treatment of women in science then, Rutherford had written this opposing view in 1920 in The Times of London: For our part, we welcome the presence of women in our laboratories on the ground that residence in this University is intended to fit the rising generation to take its proper place in the outside world, where, to an ever increasing extent, men and women are being called upon to work harmoniously side by side in every department of human affairs.

Cambridge didn't offer fully certified doctoral degrees to women then, however, so she attended a connected school Newnham College instead. There, she studied ionized mercury vapor lamps and its surface chemistry on the electrodes. In 1926, she became the first woman to receive a PhD in physics there, but her doctorate was recognized academically without full university membership rights as a man's. Upon returning to GE, she was also the first woman scientist there with a PhD.

Graduation photo from Cambridge University, 1926, showing Blodgett as the only woman (University of Cambridge)

Katharine's main contribution to science began before she was hired at GE. When Langmuir joined GE in 1909, he was told to fix a problem with jewelled bearings in electric meters. Friction caused them to work inaccurately, but his research into oil coatings led to intense surface chemistry studies. By 1917, Langmuir had published a groundbreaking paper on the chemistry of oil films. His theory was that the films were only one molecule thick, and he could measure what that thickness was. See image below.

Applying oil to powder on a water surface, resulting in spreading of oil in a circular shape.

This was used by Langmuir to determine how thick the oil layer was. (edisontechcenter.com)

He demonstrated that when oils were applied to the surface of water, they spread out in a thin film, and by calculating how much had been added and the diameter of that film, the thickness could be calculated. The oils were called amphiphilic, which means they have an end which dissolves in water (hydrophilic) and one that does not (hydrophobic). That single-molecule-thick layer could be deposited

Image from master's paper by Mikkelson, 2012

onto a glass or metal plate by dipping it into the water tank or lifting it out after being submerged. The special tank was called the Langmuir trough (a spinoff of what Agnes Pockels had designed in 1862). Langmuir pulled glass out manually, while Blodgett modified it with a steady clamp. That version was then called the Langmuir-Blodgett trough. Langmuir eventually won the 1932 Nobel Prize for the work, even though Blodgett had contributed practical uses for their discoveries.

Animation showing how amphiphilic molecules make a layer in a Langmuir-Blodgett trough, then are compressed to maximum density before sticking them to glass as it is pulled through the layer (MCeep)

From 1927 to 1932, her work at GE was related to light bulb filaments and the surface chemistry of gases or electrons with them. After Langmuir returned from accepting the Nobel Prize, they advanced his research on thin films by examining similar properties of various lipids, polymers, and proteins. The work began as a means to coat beads, but in 1935, Katharine found that dipping a metal or glass plate multiple times allowed her to stack oil layers onto the plate. She learned how to control exactly how thick the layers of molecules were. 

Blodgett and Langmuir at General Electric (bellapart.com)

Blodgett noticed that as she added layers, the color of the film on the glass changed. This was an indication of the thickness, or the number of layers, each just one molecule thick. At 44 layers, something remarkable happened. The glass reflected only 1% of the light. Without a coating it normally reflects 4-10%, but with 44 layers of calcium stearate film, 99% of the light passed through the glass. That made it glare-free, essentially non-reflective, and "invisible". GE made the announcement on  December 27, 1938.

Magazine article announcing her discovery. (mujeresconciencia.com)

Blodgett demonstrating non-reflective glass on eyeglasses after Langmuir introduction 

(abridged video from YouTube)

With multiple treatments on glass surfaces, Blodgett realized how the layers were positioned with alternating layers of the amphiphilic ends matching each other.

Diagram of what 3 layers of film looks like with alternating hydrophilic & hydrophobic ends. (ACS Publications)

Katharine also noted that the various number of layers on glass seemed to produce disctinct colors of film. She reasoned that a color gauge would help to determine the thickness that way, and so she built one herself. The most sensitive instruments at the time could measure to a few thousandths of an inch, but even 200 layers of oil film were much thinner. Her gauge gave measurements down to less than one millionth of an inch. It was later refined by GE, but the basic design has continued to be used by metallurgists looking at steel coatings, biochemists measuring swelling of blood cells, and biologists studying antibodies.

Blodgett's color gauge (lostwomenofscience.org)

The only color photo found (Hackaday.com)

Blodgett knew calcium stearate was easily rubbed off, which made it unsuitable for permanent use, but she said it was still good enough for her experiments. A few days after her announcement, MIT labs showed a stronger method, and later Bausch & Lomb improved on her process to fix films more permanently on camera lenses. Before long, the treatment was also applied to windshields, picture frames, eyeglasses, telescopes, microscopes, computer screens, and with the advent of World War II, its use on submarine periscopes was invaluable.

Demonstrating non-reflective glass to her peers (WMHT)

By the time Katharine had made her discovery of non-reflective glass coatings, World War II needed her once again. In 1940, General Electric was called upon to fix two problems. One was that existing smoke screens would not cover a large enough area in military field operations and were not dense enough. These were created by generators that would vaporize oil. Problems included the following with existing technology:

• many men were needed to maintain them on an hourly basis
• they stained clothing
• they irritated noses and throats
• they covered small areas but not the square miles desired
• they were potentially explosive

Smoke screens were not made of smoke like from a wood fire. Aerosolized particles would reflect sunlight and make viewing inside difficult. Langmuir determined that the best particle size would be one micron in diameter. With Blodgett and others, they developed the M-1 generator, which sent the tiny particles out too fast to bump into each other and make larger ones, so the smoke screen was effective longer, more densely, and over a larger distance. Tested in June 1942, it covered 20 miles in a California valley. By November, they had been manufactured and used in North Africa to cover U.S. troops.

M-1 smoke generator (custermen.com and Popular Science, July 1943)

Another wartime project involved the icing of airplane wings. Supercooled water droplets in clouds remain liquid below freezing temperatures, but they freeze immediately when striking a solid surface (wings). That adds weight (reducing fuel usage) and drag (hindering flight maneuverability). Blodgett and Langmuir built one of the first controlled laboratory systems for producing supercooled droplets. They measured the fraction that struck, exactly where they landed, and how droplet size affected impact. The most dangerous conditions were found to be droplets 20-40 micrometers in diameter. Blodgett was one of the earliest users of a large analog computer built by GE to make these calculations, which helped engineers design deicing systems.

She retired from GE in 1963.

Image from WMHT

From the Biographical Dictionary of Women in Science: Blodgett was a quiet, unassuming person, who seldom talked about herself. She was a member of the Presbyterian church but was not politically active. With a reputation as an excellent cook, an amateur astronomer, and a competent gardener, she enjoyed quiet activities at home as well as out of doors, where she spent as much time as possible at her house at Lake George, New York.

On January 29, 2026, the Lost Women of Science Initiative published a podcast about Katharine's life. As part of the background, they contacted a great-niece of hers, Deborah Alkema in Massachusetts. She mentioned a storage unit of Katharine's belongings in New Hampshire, and the interviewer went to investigate. Among the various papers, they found one lab notebook she had kept from her GE research days, something you are not supposed to do. Many other things were unpacked:

• love letters from her parents
• stock certificates
• news clippings of her father's murder
• photos and headlines of her receiving awards
• a Bible study notebook

And then they came upon letters from her psychiatrist. Twelve years after she began work at GE, she had become an in-patient for 2 months. She was hearing voices. Sometimes they were encouraging remarks like "Good job!" But they persisted beyond two months. The vast amount of clippings about her father's death may have been weighing on her, even to the point of taking part in seances to contact him. She kept written correspondence with a second psychiatrist for years. Was her affliction related to the loss of her father or to being the only woman in a male-dominated GE laboratory or not getting full recognition for her efforts or interacting with another personality within herself? The answer will never be known.

What is known is that, aside from the personal description in the Biographical Dictionary of Women in Science above, she published 30 papers and received 8 patents (6 of them all by herself). She won many awards and honorary doctorates before and after taking part in two World Wars from the lab bench. 

Katharine at her desk at GE (Hackaday.com)

She spoke at many gatherings to promote the role of women in science. Once, in 1939, she was introduced in good company as follows:

Women and their organizations continue to play an important part in the proceedings of the forum with several speakers of prominence on the program. These include Mrs. Franklin D. Roosevelt, who will speak at the first session, Mme Chiang Kai-shek, who will broadcast a message during the fourth session; Dr. Katharine Blodgett, discoverer of ‘invisible glass,’ who will speak at the fourth session…

Katharine happily demonstrating the Langmuir-Blodgett trough to visitors (American Physical Society)

Katharine never married, but she spent much time with her niece and children, entertaining them with fragments of her own research. Her niece said of her: 

I have wonderful recollections of stuffed animals and chocolates and board games. She entertained us with marvelous stories about Houdini....[She] "always arrived with suitcases full of 'apparatus', with which she showed us such wonders as how to make colors by dipping glass rods into thin films of oil floating on water."

She was also known as a prankster as far back as university days and for being very witty with the English language. When challenged to make a rhyme with the word polyvinyl, she wrote this:

"That formaldehyde polyvinyl

If you eat it, you'll dine ill. 

One night at a party, 

When the guests all ate hearty, 

By actual count it made nine ill."

Katharine Burr Blodgett while at GE (Women in the National Inventors Hall of Fame)

. Katharine Burr Blodgett died on October 12, 1979 of cerebral thrombosis from an earlier car accident.

What do we know about pine cones?

Various pine cone designs (Dyck Arboretum, Hesston College)

Pine cones are the seed-bearing organs of conifers and cycads (trees with cones and needle-like or scale-like leaves that are typically evergreen). Conifers are members of the group of plants called gymnosperms, and in addition to having cones and needles, they do not have flowers but their seeds are "naked". That means they are exposed on the cones instead of being protected inside an ovary or fruit like angiosperms (flowering plants).

Cycad Encephalartos lehmannii from South Africa with its one cone

(South African National Biodiversity Institute)

Pine cones come in many sizes and shapes. Sizes range from 2.5-5 cm (1-2 inches) to >50 cm (>20 inches). They can be long and slender or rounded or oblong. Some have thin parts (bracts, see below), while others are thick and look almost like a wood carving. Many have single cones growing independently, others have pretty clusters, and others like Lodgepole pine (Pinus contorta) show twisted groupings.

Various shapes and groupings of pine cones.

Top left, white pine; Top middle, Coulter pine; top right, Lodgepole pine.

Bottom left, Scots pine; bottom center, Bosnian pine; bottom right; Ponderosa pine.

Images from AZ Animals.

Some remain closed until humidity or moisture conditions are right. One, the Lodgepole pine, opens only after fire exposure. 

There are male and female pine cones. Males are smaller than females, and they tend to hang from lower branches while females are higher. Since they produce pollen, they are also called pollen cones. They are also lighter in color and softer. They fall off every year. On the other hand, female cones are hard and woody, and they produce seeds, so they care sometimes called woody cones or seed cones. They take 2–3 years to mature, stay on the tree after releasing seeds, and may remain attached for several years (decades for Lodgepole pine).

Male and female cones from Doublas fir (Allerma)

In true fir trees (genus Abies), the cones do not fall off whole like pine or spruce cones. After the seeds mature inside, the cone scales loosen and drop off one at a time. Seeds are released gradually, leaving just a bare central spike (the cone axis) sticking up.

Abies fir cone whole (left) and fallen apart with age (right) (Wikimedia)

With angiosperms, pollen is carried by wind, rain, insects, animals, or just close contact. But with gymnosperms, only the wind carried pollen to spaces inside the cone body (or strobilus). Notice that the leaf-like tips of the female cone body are not the seeds. They are called scales and two types are there for protection (seed scale) or support (bract scale). Both are modified leaves! 

Seeds form deep inside near the central stem of the cone, and pollen needs to get that far to meet up with the ovule to fertilize it and create a seed. When the scale opens, it allows the seed to fall out.

Diagram of female pine cone in cross section (from Libre Texts)

But female cones don't always look this open. When the air is dry, the cone scales lose moisture. As they dry, the scales shrink unevenly. This causes them to bend outward. The seeds are then released to gravity or the wind. Since this happens in dry weather, seeds have a greater change to float on the wind farther to spread the growth of more pines.

Video showing a pine cone opening as daylight dries the air

You can force pine cones to open and close yourself. Put open cones in warm water and watch them close. Or to dry them, you could heat closed ones in a microwave oven and watch them open.

The bract are very tightly bound when cones are closed. As they open, you can even hear them make a cracking or snapping sound.

 

Videos demonstrating the sound of female pine cones opening

The seeds of pine cones are sometimes edible, and in those cases they are called pine nuts. The following are pine nuts you can eat:

• Pinus pinea (Mediterranean/European variety, Italian stone pine)
• Pinus koraiensis (China, Korea, parts of Japan)
• Pinus sibirica (East Asia)
• Pinus edulis (Colorado pinyon)
• Pinus monophylla (American Southwest)
• Pinus lambertiana (sugar pine, Western United States (California, Oregon, parts of Nevada))

Many pine nuts can be eaten, but they may simply be too small to make it economical, whether on a large scale or in simple foraging in the woods by yourself. In all cases, the shells must be removed before the seed inside can be eaten.

European pine nuts after shell has been removed (Wikipedia)

Of course, many animals eat pine nuts. Squirrels, chipmunks, birds like crossbills, woodpeckers, and jays, even bears are the main foragers. They are all after the fiber and nutrients in the seeds, such as 

• Vitamin K
• Manganese
• Protein
• Thiamin
• Zinc
• Phosphorus 
• Magnesium

Pine nuts also contain 670 kcal/100 grams, 13–14 g of protein/100 grams, 68 g of fat/100 grams (mostly unsaturated heart-healthy, but also some polyunsaturated and monounsaturated),  13 g of carbohydrate/100 grams, and a fatty acid like pinolenic acid.

If you want to collect pine nuts in the forest, here is one video to show how it can be done with a gentle method. Here is another video with a bit harsher method. Both offer some good tips that the other one doesn't. 

Screenshots from the two videos above

Squirrels tend to eat green immature female cone seeds, but they will eat mature nuts, too. The immature seeds are more tender. And, with green cones, there is less chance that some of the seeds might have fallen out of the cone, so they get more per cone!

Upper cone uneaten, bottom cone completely eaten (Discover Wildlife)

Did you know that squirrels might be considered left- or right-handed? You can tell by the way they pick at a cone vs hold it as they eat. The hand rolling the cone is what is used to judge lefthandedness or righthandedness. The other one merely steadies it. According to one website, "Squirrels will start at the bottom and work their way upwards in a spiralling motion. If the spirals go [counter]clockwise then they are left handed, and if they go clockwise then they are right handed!" Other researchers at the Universidad Autónoma de Madrid classified 893 pine cones they found as "left-gnawed" or "right-gnawed". The type of cone didn't matter, but populations of red squirrels only 30 km away from each other were either lefties or righties.

This squirrel appears to favor his right paw to turn the cone.

Researchers from the State University of New York also learned that the farther away a squirrel is from its home, the shorter time it takes to each nuts. When they ate 200 seeds 5 meters (16.5 ft.) from cover, they held each seed for a little over five seconds, but when they were 15 m (50 ft.) from cover, they handled each seed for less than two seconds. That's not their idea of "fast food", but more closely related to self-preservation. Sitting in the open further from cover is more dangerous.

Data from the study described above. Handling time in seconds.

Recipes for human consumption of pine cones are more numerous than you might think. 

A Russian recipe for jam boils them for 30 min, allows them to sit for 12 hours, then removes the cones and adds sugar. A few finishing touches produces a thick jam. Another recipe simply alternates cones and sugar, and over time a honey-like syrup is formed. Another chops and brews very young cones to make a tea.

This video shows how to make pickled pine cones. 

Mugolio is another sweet syrup, but this takes longer. This website has a lot of details, but essentially you just add brown sugar to green pine cones, cover, and wait a month or more.

Mugolio at different stages (Forager Chef)