Memorial Day, Building Muscle, and a Bird Encyclopedia

Memorial Day, explained

Memorial Day is a federal holiday observed on the last Monday of May, honoring the men and women who died while serving in the US military. Originally called Decoration Day, its origins trace to the aftermath of the Civil War, when communities across the country began holding local ceremonies to decorate the graves of fallen soldiers. The first national commemoration was held at Arlington National Cemetery on May 30, 1868.

Over time, the holiday has come to be both a solemn day of remembrance and the unofficial start of summer. Congress moved it from May 30 to the final Monday in May in 1971, creating what is now one of the biggest travel and cookout weekends of the year in the United States.

Today, traditions include visiting cemeteries, attending parades, and the National Moment of Remembrance at 3 pm, when Americans are asked to pause and honor the fallen.

... Read what else we learned about Memorial Day here.

Also, check out ... 

> One of the earliest Memorial Day ceremonies was held by newly freed Black Americans in South Carolina. (Read)

> The American Battle Monuments Commission maintains 26 overseas military cemeteries in 16 countries. (Explore)

> The Indianapolis 500 has been tied to Decoration/Memorial Day since 1911. (Read)

> Cookout and barbecue culture boomed in postwar 1950s America. (Learn)

In partnership with Babbel

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What we learned about resistance training

Resistance training is a type of strength and endurance exercise that works muscles against an external force, helping preserve muscle mass and bone density. It includes exercises like squats, pushups, shoulder presses, and more to boost the brain and body—whether we're lifting body weight, dumbbells, barbells, or using resistance bands.

Exercise physiologists suggest starting the practice early, noting it particularly benefits women in menopause because estrogen reductions can lead to bone density loss, which increases the risk of osteoporosis and bone breaks. Resistance training complements aerobic exercises like swimming or running, which typically keep your heart rate elevated over extended periods, improving cardiovascular health.

Adult fitness recommendations include resistance training twice weekly and performing 150 minutes of moderate aerobic exercise, though about 80% of us don't achieve this. When done consistently, resistance training is linked with reduced depression and anxiety and elevated cognition. It improves glucose control, reduces fall risks, and supports grip strength—the amount of force someone can generate with their hand and forearm muscles—a strong predictor of broader health risks, including falling and early death.

... Read our full page on Resistance Training here

Also, check out ... 

> Follow a how-to video series on how to start strength training. (Watch)

> Strength training can be done with everyday household items. (Read)

> Arnold Schwarzenegger fueled a lot of the interest in strength training, beginning in the 1980s. (Watch)

> Modern bodybuilding evolved in the 19th century. (Listen)

Crude oil, explained

Crude oil is the world's primary energy resource. Predominantly composed of molecules of hydrogen and carbon, the mixture formed when microorganisms, such as algae and plankton, were compressed and heated under layers of sediment for millions of years (watch explainer). Although used as early as 3,000 BCE to waterproof boats, crude oil was not widely extracted and refined until the mid-19th century, when it increasingly transformed society as a raw material for fuels, plastics, cosmetics, pharmaceuticals, and more.

Engineers find oil reservoirs by mapping subterranean contents using a variety of techniques, including gravity, magnetic, and seismic reflection surveys, before drilling a well for extraction (watch example). Because the extracted oil is "crude"—an unsorted mix of hydrocarbons—refineries typically boil it to produce a vapor mixture. In a fractional distillation tower, where temperature decreases with altitude, these vapors are sorted into layers as they condense back into liquid at distinct heights.

Once distilled, sorted hydrocarbons are separately processed into useful petroleum products. This includes cracking, which breaks larger molecules into smaller ones, like the building blocks for plastics, and reforming, which makes the various octane blends available at gas stations. These processes, along with leaks and spills, are sources of toxic pollutants that can cause significant environmental damage and adverse health effects for those living near refineries.

... Read everything we found on Crude Oil here.

Also, check out ... 

> Aspirin, polyester, chewing gum, and other objects you might be surprised to learn are derived from crude oil. (View)

> Decommissioned oil rigs can be repurposed into artificial reefs. (Watch)

> How we get 45 gallons of refined products from a 42-gallon barrel of crude oil. (View)
> Understanding why the US depends on global markets rather than its own crude oil. (Watch)

In partnership with Babbel

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Best of the Week

We added 288 resources this week to our knowledge collective—share your favorite link or outlet with us to see it featured here next week!

Exposing fetuses to certain flavors in the womb could lead to children being less picky eaters.

Humans are more genetically similar to cats than to dogs (w/quiz).

See projections for how populations across the world could change in the 21st century.

Learn about the violent history of the nutmeg industry.

Explore the Council on Foreign Relations' essay collection on the future of US foreign policy.

See who sat where at the US-China state dinner.

Meet the man whose 100-patty In-N-Out order permanently changed the menu.

Explore why Americans are drinking less alcohol.

Visualize every time Congress has mentioned the word "democracy" since 1880.

See 10 of the artifacts on display at the Smithsonian's America at 250 exhibition.

How the gut microbiome influences your emotions.

A comprehensive encyclopedia of all known bird species.

Unpacking the mysterious work of management consultants.

See an animation depicting the devastating volcanic eruption in Pompeii.

Common phrases that are attributed to William Shakespeare.

Historybook: United Kingdom's Queen Victoria is born (1819); New York's Brooklyn Bridge opens to the public (1883); Musician Bob Dylan is born (1941); Four men are sentenced to 240 years in prison for the 1993 World Trade Center bombing (1994); Musician Tina Turner dies (2023)