Read more about the article Radio Waves

Radio Waves

From wireless telegraphs to 5G data, the modern world runs on radio waves.

In the electromagnetic spectrum, radio waves are the lowest frequency & longest wave length waves available. The name “radio” doesn’t mean the waves are just for radios, it comes from the idea to “radiate energy” and the waves are used for lots of things. Wireless telegraphs, TV broadcasts, walkie talkies, radar, GPS, wireless routers, bluetooth, your mobile phone data – it’s all radio waves.

The existence of radio waves were proposed in 1867 by James Maxwell, but it took twenty years until 1887 for Heinrich Hertz to first demonstrate them (and because of this the hertz unit of measurement was named for him). The potential of radio waves was first realized by Guglielmo Marconi who used them to create wireless telegraphs. Marconi’s invention allowed people to send messages wirelessly through the air (which won him the 1909 Nobel Prize in physics). His invention is also one half of the very good Erik Larson book Thunderstruck.

Radio waves sit on the far end of the electromagnetic spectrum.

The Wave

We can send & receive data through the air thanks to transmitters & receivers. A transmitter antenna will send out a radio wave, modifying the wave form as need be. Then a receiver antenna will take the wave and process it as information. In the modern world most of that information is converted into binary ones & zeros as data.

Rather than sending out a consistent steady wave (which wouldn’t be very useful), transmitters modulate waves in various ways. You can modulate a wave’s amplitude as well as its frequency (which, incidentally, is why we have AM and FM radio – amplitude modulation and frequency modulation). You can also change where you begin & end a wave’s phase. This can create thousands of combinations, each of which can mean combinations of binary data. Using this complicated system of changing wave types we can have lots of devices sending & receiving information in relatively close proximity to one another. This is perhaps best demonstrated in the prolific use of mobile phones.

Cellular data (and the 5G boogeyman)

Mobile phones interact with antennas to send & receive data using radio waves. Each antenna covers a certain territory (a cell), but they are all working together (a network) – hence “cellular network”. Early mobile car phones had very few antenna to interact with so, once you left one’s area, you lost service. As mobile phones became popular in the 1990s more complex cellular networks with many towers were created.

5G is the fifth generation of the technology that runs these cellular networks. The challenge for 5G is to give even more devices even faster information. Part of how it does this is through an increase in the number of antennas. It also uses a wider range of wave frequencies. 5G uses radio waves but it also uses higher frequency microwaves (millimeter waves) to send more information, faster, across short distances. To do this the millimeter waves use smaller network cells, with more antennas, closer to the ground than the typical radio waves use.

As 5G was arrived out so too did the conspiracy theories.

The rollout of 5G began in 2019 and with it came the conspiracy theories. Some people claimed 5G weakens our immune systems leaving us vulnerable to viruses (such as COVID-19). Others claimed Covid was caused by 5G waves or that the Covid vaccines contained secret microchips that would be controlled by 5G. There are also conspiracy theories that 5G causes cancer and specifically because of the millimeter microwaves. None of this is true.

The waves used in 5G are non-ionizing waves (meaning they do not remove electrons from atoms or damage human cells). Ionizing radiation is found on the other end of the electromagnetic spectrum beyond visible light. Ultraviolet, X-rays, and gamma rays will damage your cells, radio waves and microwaves do not. The waves used in 5G can’t penetrate your skin and no credible study has found them to be dangerous to humans. Alcoholic drinks and processed meats have higher likelihoods of causing cancer than 5G.

A really great explanation of how modern cellular networks operate.

A crash-course on 5G data.
Read more about the article Honey & Allergies

Honey & Allergies

Eating local honey doesn’t help with your seasonal allergies (but it tastes good at least).

Broadly speaking, trees and other plants use one of two methods for reproduction. One method is to rely on bees, animals, or other creatures to interact with the plant and then spread the pollen to other plants. The second method is to release pollen into the wind and hope for the best. It’s this second category, scattering pollen to the wind, that people are allergic to when they have seasonal allergies. 

Delicious but unhelpful

There is an idea that eating local honey can help you deal with seasonal allergies because local honey is made from the local pollen you’re allergic to – that through exposure to small amounts of what triggers your allergic reaction you can teach your immune system to not react (ie. immunotherapy). Unfortunately this doesn’t work for a few reasons.

To start, when you consume local honey you don’t know what sort of pollen it contains or in what amount. So while it may theoretically contain the pollen that triggers your allergic reaction you can’t be sure and every batch of honey is different.

Further, local honey is made with the “wrong” kind of pollen. Honey is made with the pollen bees collect through physical contact with plants, but the pollen of your seasonal allergies is the kind that’s spread on the wind. As such there isn’t going to be much (if any) of the pollen that triggers your allergies in honey. Therefor eating local honey won’t help with your seasonal allergies.

Read more about the article Slippery Rail Season

Slippery Rail Season

The annual autumnal slow-down of regional rail is due to crushed leaves releasing oil on the tracks.

After the leaves change into their autumnal colors they fall to the ground. The ones that fall on rail lines are responsible for slower trains. As trains roll on down the line they crush any leaves on the rails, releasing pectin which acts as a low-friction grease making it harder to control the train. This is even worse when it rains. It becomes harder to slow down a train but also harder to accelerate again, resulting in delays. This is slippery rail season.

Transit organizations try and deal with leaves in a variety of ways. Trains & cars equipped with pressure-washing machines spray the tracks to remove the residue and uncrushed leaves (NJ Transit calls the train that does this the “Aqua Train”). Some organizations will also apply a mixture of gel & sand to increase traction.

Added info: another place you want traction is Pamplona, Spain during the Festival of San Fermín and the running of the bulls. Every morning, before humans and bulls run down the tight cobble stone streets of Pamplona, crews clean all trash from the streets as well as coat several sections of the route with a chemical anti-slip substance.

How SEPTA deals with leaves in the Philadelphia area.

An extended explanation from the MBCR on how they clean slippery rails in New England.
Read more about the article Behind the Auroras

Behind the Auroras

The Aurora Borealis & Aurora Australis are both beautiful light shows as well as visual signs that the Earth’s magnetosphere is still protecting us from a constant barrage of destructive particles from the Sun.

The lights

In mythology & folklore the Northern Lights have been seen as both good and ill omens. This tended to depend on your degree of latitude which dictated how frequently you saw them. Northern people more accustomed to the lights such as those of Sweden, Norway, and Finland saw the lights as the energies of the departed and worthy of respect. Similarly, different peoples of Alaska saw the lights as the dancing spirits of humans or animals. Further south in ancient Rome, where the lights were seen less frequently, they were seen as a harbinger of war or famine.

Scientifically, the aurora are the result of charged particles from the sun (protons & electrons) interacting with oxygen & nitrogen in the Earth’s atmosphere. The different colors are the result of which gases the particles encounter at which altitudes. The most common color is yellow-green which is the sun’s particles interacting with oxygen at around 60 miles above the Earth. Nitrogen produces blue light below 60 miles in altitude but produces purple light above that. Red is also produced by oxygen but at altitudes above 150 miles. The light produced in these exchanges lasts only a second or less but the steady stream of particles from the sun can create long lasting light shows.

The aurora are the reaction of protons & electrons from the sun interacting with gases in our atmosphere.

Special Delivery

The sun is constantly emitting these charged particles. The solar wind regularly delivers a steady stream of particles to Earth but they are also unleashed in larger more powerful bursts through solar flares and coronal mass ejections (CMEs). When any of these charged particles approach Earth their path is directed by the Earth’s magnetosphere which is essentially a magnetic force-field generated by the Earth. The magnetosphere deflects most of these particles around & away from the Earth, however some particles are pulled down towards the magnetic northern and southern poles. It’s these particles pulled towards the poles that create the dazzling auroras.

Earth’s magnetosphere directs the sun’s particles towards the poles. It’s also what keeps us alive.
The Earth’s magnetosphere acts a shield, deflecting & directing particles from the sun.

So where is the danger?

The key to the aurora light shows, and our survival, is the magnetosphere. Without it, Earth would be subjected to the full brunt of the emissions from the sun. If left completely exposed these charged particles would gradually strip the Earth of its atmosphere. No atmosphere, no life. It has been theorized that Mars once had a magnetosphere but lost it approximately 4 billion years ago. As a result the atmosphere was carried off into space by the solar wind. With no atmosphere the water of Mars boiled off leaving Mars a barren wasteland.

So the light shows of the auroras are the direct result of the constant defensive protection of the Earth’s magnetosphere. This shield protects all life on Earth from the never-ending stream of charged particles that would otherwise end life on Earth as we know it.

Read more about the article Rock Columns

Rock Columns

As lava/magma cools & contracts it can form polygon stone columns.

Columnar jointing is a rock formation where fractures (joints) occur in cooling volcanic rock. As the lava/magma cools from the outside inward it shrinks towards center points. This shrinking then continues from the top down forming columns of rock. These stone columns are frequently hexagonal with six sides (a shape very common in nature) but other numbers of sides occur as well.

These rock formations can be straight vertical columns (the Giant’s Causeway, Devil’s Tower, Svartifoss, etc.) but can also form with sideways irregularities due to how the molten rock moved and cooled (such as Alcantara Gorge where the lava cooled diagonally).

Devil's Tower
Devil’s Tower in Wyoming features the tallest columns in the world. On the right is a climber ascending the Tower, giving scale to the enormity of the columns.

Rock Folktales

Because they look carved and intentionally organized they don’t seem natural. Cultures around the world have come up with a variety of explanations for these rock formations. Devil’s Tower in Wyoming is a striking example of columnar jointing which features the tallest columns in the world. Its name varies by different Native American groups but it tends to be versions of “Bear’s Home”. According to tradition, as children were fleeing a great bear (or bears) the animal’s claws dragged down the rock face, carving the columns we see today.

the Giant's Causeway
The Giant’s Causeway in Northern Ireland, created by Irish giant Fionn mac Cumhaill, features thousands of columns. It’s also featured on the album cover of Led Zeppelin’s 1973 album Houses of the Holy.

The Giant’s Causeway in Northern Ireland is perhaps the most famous example of columnar jointing. As the legend goes the causeway was formed by Irish giant (or just regular sized superhero) Fionn mac Cumhaill (Finn MacCool). He built a series of stepping stones to connect Ireland to Scotland. Longer story short, the Scottish giant Benandonner smashed the causeway during his retreat from Ireland back to Scotland. Today the remnants of this “causeway” are the rocks at the Giant’s Causeway and a similar rock formation on the Isle of Staffa (the most famous part of Staffa is Fingal’s Cave, named after Fionn, which was a very popular source of inspiration for the arts in the 19th century).

Svartifoss
Iceland’s Svartifoss falls has served as the inspiration for Hallgrímskirkja church among other places.

In Iceland, a volcanic hotspot in the past as well as today, there are several examples of rock columns. The rock formations along the black sand beach of Reynisfjara are said to be two trolls who were dragging a three-masted ship to land. As they fought over the ship they lost track of time and dawn came, turning the trolls into the rock columns. The rock columns at Svartifoss were the inspiration for Hallgrímskirkja church in the center of Reykjavik. The hexagonal shapes of Svartifoss also influenced the design of the Harpa concert hall.

Added info: Columnar joint formations are not limited to Earth. The volcanism involved in the formation of Mars also created stone columns in much the same way we have them here.

Nick on the Rocks explains columnar jointing.
Read more about the article New England Vampires and Tuberculosis

New England Vampires and Tuberculosis

The effects of tuberculosis led some 19th century New Englanders to believe that vampires were preying on the living.

In the late 18th and much of the 19th century there was a vampire panic in New England. People across New England feared that vampire-like creatures, using some kind of sympathetic magic, were slowly killing their friends & family from inside the grave (as opposed to traditional vampires who rise from the grave to attack). People would exhume their family members, look for the one who might be a vampire, and take various precautions to stop them. New Englanders might remove & burn the heart of a suspected vampire, they may turn the skeleton over facedown, decapitate the head, put a brick in their mouth, or use a wooden stake to pin their relative to the ground among other methods.

This panic was more than just a few isolated incidents. Henry David Thoreau mentions attending an exhumation in his journal on September 26, 1859. In February of 1793 over 500 people attended the ceremonial burning of the heart, liver, and lungs of supposed vampire Rachel Harris in Manchester, Vermont. After Nancy Young died in 1827 Rhode Island, her father thought that she might be preying on her still alive little sister Almira. The family exhumed Nancy’s coffin, burned it on a pyre, and stood in the smoke to breath in the vapors thinking it would free/cure them of this affliction – it did not work and Almira and two more of her siblings later died. Digesting the cremated remains of a suspected vampire, or breathing in the smoke of the cremation pyre, were not uncommon last resort treatments after traditional medicine had failed.

The 1892 exhuming of suspected vampire Mercy Brown in Exeter, Rhode Island became an international story – Bram Stoker based part of the Lucy character in Dracula on Mercy Brown. With 18 confirmed vampire cases, Rhode Island even become known as the “Vampire Capital of America.” The reason all of this happened was twofold: tuberculosis and decomposition.

The story of Mercy Brown influenced Bram Stoker’s Dracula.

Wasting away

Tuberculosis is an airborne disease that attacks the lungs (among other areas). Active tuberculosis kills about half of those infected and in 2018 it was the ninth leading cause of death worldwide (killing more people than Malaria or HIV/AIDS). In 19th century New England tuberculosis was the leading cause of death, killing an estimated 25% of the population.

Tuberculosis can develop over months or even years, slowly eating away at someone. A person with active TB develops a chronic cough as their lung tissue breaks down, their mucus starts to contain blood, they develop fevers, night sweats, and lose weight. Because of the weight loss the disease has been historically known as “consumption.” As the infected person wastes away they also develop ashen skin, giving them an overall sickly drained appearance.

Vampires, or, a lack of scientific understanding

The effect of tuberculosis (the slow draining of life) combined with some of the infected saying their deceased relatives were visiting them (as Almira Young claimed), was enough for some New Englanders to suspect there were vampires at work. Bodies of suspected vampires were exhumed to looks for signs of vampirism. Some of the corpses seemed have grown longer finger nails and longer hair, some were bloated, some had blood in their organs, while others seemed to have not decayed at all. These were surefire signs of a vampire … or were just normal aspects of body decomposition.

As bodies decay they become dehydrated causing the skin to recede and shrink. This gives the illusion of longer fingernails & hair as the base of the nails and hair that was once under the skin is now exposed. The bodies that seemed to have not decayed at all were the ones of people who died in the cold winters of New England (as was Mercy Brown’s case who had died in January) where the cold slows the decomposition process. These unremarkable signs of decomposition were mistaken as proof of life after death to the untrained eyes of 19th century New England.

The dawn of a new era

The Mercy Brown story brought unwanted attention to New England. It was embarrassing that, while the light bulb was being invented and Henry Ford was building his first car, people were worried about folklorish undead monsters. The vampire panic rose and fell with the tuberculosis endemic of New England. Over time with advancements in science, and the dissemination of knowledge, belief in vampires faded away.

Added info: porphyria is another disease whose symptoms can be similar to vampire activity. It’s a liver disease that, for some, can cause sensitivity to sunlight (leading some to only come out at night) as well as sensitivity to garlic.

“Ask a Mortician” goes through the history of the New England vampire panic and the realities of tuberculosis in 19th century New England.

A crash course on tuberculosis.
Read more about the article Brain Freeze

Brain Freeze

The short headache triggered by cold food and/or drinks touching the inside of your mouth.

To start, brain freeze (aka “ice cream headache” or “cold-stimulus headache”) only affects about 30-50% of the population. Most people can eat ice cream and drink extra cold drinks without any fear of reprisal from their nervous system.

Brain freeze occurs when the roof of your mouth or the back of your throat suddenly come into contact with cold food, cold drinks, or even cold air. The trigeminal nerve in your head reacts to the cold by telling the arteries connected to the meninges (the membranes surrounding your brain) to contract to conserve warmth (much like how our bodies react to the cold in general). Then the body sends more warm blood up to the head telling those same arteries to expand. This quick succession of vasoconstriction and vasodilation of blood vessels triggers pain receptors along the trigeminal nerve which creates the pain you feel behind the eyes or forehead during a brain freeze.

A lot of nerve

While we all have a trigeminal nerve its varying sensitivity may explain why not everyone gets brain freeze. For example 37% of Americans may get brain freeze but only around 15% of Danish adults do. Further, 93% of people who get migraines are also susceptible to brain freeze.

Read more about the article Color Blindness

Color Blindness

The visual condition that changes what colors you see, which is mostly found in men and is mostly hereditary.

To start, being color blind almost never means someone is blind to color, as if they’re living in a black & white movie. “Color blind” usually just means someone doesn’t see the full spectrum of colors like the rest of us. To understand color blindness we have to understand two concepts: light and our eyes.

Let there be light

The colors that we see are photons moving at different wavelengths/frequencies. They’re part of the electromagnetic spectrum. The full electromagnetic spectrum ranges from Gamma rays (the shortest, highest frequency waves – quite dangerous) to radio waves (the longest, lowest frequency waves – not so dangerous). What we call visible light is radiation in a particular range of wavelengths. Within this bandwidth the colors of violet and blue have the shortest wavelengths while oranges and reds have the longest. Through evolution we have developed two small biological machines capable of detecting this range of wavelengths … our eyes.

the electromagnetic spectrum
The electromagnetic spectrum ranges from gamma rays to radio waves, photons moving at a variety of wavelengths & frequencies.

Doctor My Eyes

Our retinas have two kinds of photoreceptive cells: rods and cones. Rods see light & dark while cones see color. We have about 120 million rods per eye and but only 6-7 million cones per eye. Instead of just one kind of cone cell we have three and each kind is tuned to a certain range of wavelengths (short, medium, and long). To put it another way, our three kinds of cone cells are each tuned to see certain ranges of colors – blues (short), greens (medium), reds (long).

Bringing it all together, color blindness is when one (or more) of your cone cell types are either defective or missing entirely. The result is that you are unable to properly see certain wavelengths of colors.

Color Blindness

Why does color blindness happen? While color blindness can be an acquired condition most of the time it’s genetic. The most common forms of color blindness are carried on the X chromosome and because men only have one X chromosome, if it’s defective they’re out of luck. This is why men are more commonly color blind than women. Women have two X chromosomes so a functioning X chromosome will compensate for a defective one. As a result around 8% of men are color blind compared to only around 0.5% of women. That said color blindness isn’t evenly distributed across men – it has a higher prevalence amongst Caucasian men than other ethnicities.

red-green color blindness is the most common form of color blindness
Red-green color blindness is a group of different kinds of color blindness. It’s the most common form of color blindness.

Because cones come in three varieties, and those cones can be defective or absent, the various combinations of factors means there are many forms of color blindness. The most common type is “red-green” color blind (which is a few kinds grouped together) where reds and greens aren’t seen properly and shift to look more like yellows and browns. This is the result of the medium and long (green and red) cone cells being defective or absent. Red-green color blindness accounts for about 99% of all color blindness with about 1 in 12 men and 1 in 200 women having it.

Blue-yellow color blindness is where blues and greens aren’t seen properly. It’s also genetic but it’s not carried on the X chromosome so men and women are affected relatively evenly. It’s quite rare – around 0.01% of men and women are blue-yellow color blind.

Are you seeing what I’m seeing?

The effects of color blindness range from the benign to the dangerous. Accidentally wearing clothes that don’t match can be embarrassing but confusing “stop” for “go” on a traffic light can be dangerous. Color blind individuals can have difficulty determining the ripeness of fruits & vegetables. They can see sports jerseys as similar and have difficulty tracking games. The designer shorthand that red means error/bad while green means success/good (the traffic light analogy) can make a variety of safety features, dashboards, and websites more difficult to use. One positive is that color blind individuals may be better at detecting camouflage.

What do other animals see?

The concept of “color blindness” is relative. What most humans consider normal is not what most bees would consider normal, or dogs, or any other species. So when people say that most other animals are color blind, it’s just that they can’t see the same spectrum of colors that humans normally see.

To start, most mammals are red-green color blind (which to them is normal). They tend to only have two cone cell types, lacking the third we have to see a wider range of colors. So when a dog can’t find the green tennis ball in the green grass, it’s probably because they really can’t see it (especially if it has stopped rolling). Dogs rely on movement to distinguish between things more than we do. That said dogs have more rods than humans so when it seems like they’re looking at something in the dark, and you can’t see anything, they’re probably seeing something beyond your vision.

The old idea that bulls dislike the color red is untrue – they’re red-green color blind. When a matador waves a red/pink cape to attract a bull the bull is responding to the motion of the cape, not the color. Dolphins and other marine animals see even less due to having only the long wavelength cone type and are monochromatic. Deer are red-green color blind but can see more shorter wavelength colors than we can including some amount of ultraviolet which to us is invisible. Some laundry detergents contain brightening agents that are intended to brighten the colors of your clothes but can make clothes look bright blue to deer. The result is that, even if your clothes are camouflaged, the deer probably saw you long before you saw the deer.

Even beyond seeing ultraviolet, some animals can detect/see the Earth’s magnetic fields. It’s believed that robins can see magnetic field lines as a darker shading on the normal colors they already see, but they can only see it through their right eyes and only on clear days. When cryptochrome molecules in their right eyes are struck by blue light the molecules become active and allow robins to see magnetic fields which they can use to navigate as they migrate north & south. Interestingly, non-migratory bird species seem to have less sensitivity to magnetic fields than migratory birds.

Finally, contrary to popular misconception, bats are not blind and some actually have quite decent sight. While they are red-green color blind like most other mammals they have an ultraviolet sensitivity that helps them hunt as well as detect predators. All of this in addition to echolocation means they are quite capable of seeing and navigating the world around them. That said, some species of bats as well as other nocturnal animals have no cones at all and are really truly color blind.

Read more about the article Diamonds are not forever, but pretty close

Diamonds are not forever, but pretty close

Diamonds very slowly degrade into graphite … but the sun, the solar system, and many of the black holes will have died long before then.

When thinking about diamonds we can think of the Shawshank Redemption line that, “Geology is the study of pressure and time. That’s all it takes really… pressure… and time”. Diamonds mined from the Earth are carbon atoms that have been compressed over long periods of time (in the billions of years) under enormous amounts of pressure.

The sands of time

The underground pressure that forms a diamond also holds it together. Once removed from the ground the carbon atoms very, very, slowly rearrange into graphite. Graphite is a more stable arrangement of carbon atoms than a diamond, but “more stable” is extremely relative. Under normal conditions a diamond sitting in your house would take an estimated 10 to the power of 80 years (1080 years) to become graphite, which is:

100,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 years

One with 80 zeros after it, years. To put that in perspective, the universe is only around 14 billion years old, or 14,000,000,000 years old. A wildly shorter period of time.

The slow death of the universe

So what will life be like when diamonds begin to lose their luster? Nothing lasts forever, including our sun and the universe as we know it. Our sun is scheduled to become a red giant star, expanding in size to engulf Mercury, Venus, and probably Earth, in about 5 billion years. But before that happens the increasing brightness of the sun will kill off all life on Earth in about 1 billion years.

If humanity takes its diamonds aboard a spaceship (with standard Earth like conditions), and sails the universe through space & time, it will theoretically take until the Black Hole Era for the diamonds to become graphite. The Black Hole Era will be from 1043 to approximately 10100 years from now. Leading up to the Black Hole Era the stars will have burned out and the planets (and your diamonds) will have decayed because their protons fell apart. In this time of darkness the black holes of the universe will decay and evaporate into nothingness … and then, finally, your (theoretically still existent) diamonds will have become graphite.

Added info: in 1947 De Beers launched the marketing campaign that “A Diamond Is Forever” (which they used to create our modern idea of the engagement ring). Also learn more about the carat measurement of diamonds (and the other karats, carets, & carrots).

Crash Course Astronomy discusses the long … long, future in store for our universe.

And because it’s an incredible song, and it mentions diamonds (albeit as a metaphor), and it will surely be the soundtrack of our interstellar space travels … Pink Floyd’s Shine On You Crazy Diamond.
Read more about the article the Myth of 8 Glasses of Water

the Myth of 8 Glasses of Water

You don’t need to drink 8 glasses of water a day.

In short: you only need to drink water when you’re thirsty. For millions of years humans and our human ancestors survived using thirst as an indicator that it’s time for more water. It wasn’t until the 20th century that the idea of drinking 8 glasses of water a day began.

We all need water to live but liquid water isn’t our only source. Coffee, tea, juice, soft drinks, fruits, vegetables, etc. all contain water. Depending on your diet you can get around 20% of the water you need just from food. Then because coffee, milk, juice, tea, etc. are mostly water, you’re probably already getting all the water you need each day without having to drink 8 more glasses of it.

… But Maybe You Do Need More Water

Daily water consumption is about maintaining balance: you need to replace the water you lose. If you live in a hot climate, or you’re sweating from exercise, you lose water faster than someone sitting still in a temperate climate. As such you need to replace water faster than normal which means drinking more water.

Also, should you be lost on a hike somewhere, you should ration sweat not water. Try to limit your physical exertion and sweat less but drink when you need to. A common mistake is that you should ration your water which, while it’s true you don’t want to waste a limited resource, if you’re thirsty you should drink. Your water isn’t doing you any good sitting inside a bottle.

Water water everywhere

On the flip side it’s possible to drink too much water. Exercise-associated hyponatremia is where you’re engaged in an endurance activity such as running a marathon, you sweat out water and sodium, but then you only drink water. In drinking regular water you manage to replenish your lost water but not your sodium. The result is low blood-sodium levels. This imbalance can cause poor nerve communication which leads to poor muscle control, poor performance, etc. Athletes with hyponatremia can feel nauseous, develop muscle cramps, and become confused leading some to think they’re dehydrated and drink even more water (making the situation worse).

Hyponatremia is becoming more prevalent in sports as an increasing number of novice athletes participate in long-distance endurance activities. For example in the 2002 Boston Marathon 13% of runners were found to have hyponatremia from drinking too much water. Athletes need to replenish their sodium levels along with their water. Part of the solution (pardon the pun) is to drink sports beverages that contain electrolytes (which are salts and can replenish sodium levels). This is why sports drinks boast about having electrolytes.

So, if you’re thirsty, drink some water and if you’re engaged in an endurance sport remember to get some electrolytes along with your water.

Added info: to bust another myth, consuming caffeinated beverages won’t dehydrate you. While excessive caffeine has a number of downsides, drinking coffee or tea is an acceptable a way to hydrate.

Adam Ruins Everything dives into the myth of 8 glasses of water a day.