#### Ultra-Long Battery Life Is Coming … Eventually

If there was any product revealed at CES last week that pushed battery life claims to a whole new level—and raised some eyebrows too—it was HyperX’s pair of 300-hour headphones.Srinivasan, like many other technologists these days, is optimistic that relatively new developments in silicon-anode technology will improve battery life.

#### If Clouds Are Made of Water, How Do They Stay in the Air?

If it's near the surface of the Earth, this force has a magnitude equal to the product of the mass of air (m) and the gravitational field (g = 9.8 newtons per kilogram).The buoyancy force is actually the result of the air around the cube pushing against it in all directions.

#### Did QuantumScape Just Solve a 40-Year-Old Battery Problem?

Like the liquid electrolyte that sits between the electrodes in a conventional cell, its main function is to ferry lithium ions from one terminal to the other when the battery charges and discharges.

#### Physicists Pin Down the Nuclear Reaction Just After the Big Bang

Their measurement of the reaction rate, published on November 11 in Nature, nails down the most uncertain factor in a sequence of steps known as Big Bang nucleosynthesis that forged the universe’s first atomic nuclei.

#### How Does a Virus Spread in Cities? It’s a Problem of Scale

And on the flip side, New Orleans, with a population density of 431 people per square kilometer, reports 1,718 cases per 10,000.Or here’s another way to look at it: According to data assembled by the Financial Times, New York City has experienced a 408 percent increase in deaths from all causes since the beginning of the pandemic.

#### If Each of Us Planted a Tree, Would It Slow Global Warming?

So to start, let’s figure out how much carbon a single tree can hold.To convert this to mass, I’m going to assume a wood density (ρ) of 500 kilograms per cubic meter, which is half the density of water.The mass of my generic tree would then be:Illustration: Rhett Allain

#### The Sensible Math of Knocking Over Absurdly Large Dominoes

Since multiplication can be tedious after a while, let's make a computer program to calculate the height of the 29th domino assuming the starting domino is 5 millimeters tall. Here is a similar program that calculates the height of dominoes needed to get one big enough to possibly crush a car.

#### Cities Are Tucking Climate Change Fixes Into New Laws

“There are liberals or progressives who oppose climate change, but they definitely don’t want that multifamily apartment building to go up next to transit if it’s in their neighborhood.” That’s what Wiener says he found in his initial efforts to link development and transit in California last year.

#### How Dense Does a Body Have to Be to Break a Concrete Floor?

I'm going to assume the floor is made of concrete and that the gravitational force on Vision (due to his large mass) is enough to exceed the compressive strength of concrete to initiate the break.What is "compressive strength"?