Why Do Scientists Measure Things by Half-Life?

istock.com/SPmemory
istock.com/SPmemory

Reader @Procrustes tweeted at us to ask: “Why do scientists measure things like radioactive elements in half-life? Why not just measure the whole life?”

If you’re not familiar with the term “half-life,” maybe you’ve heard one of your nerd friends use it. If they weren’t complaining about a guy named Gabe and ranting about steam and a valve, they were probably using it in reference to radiometric dating, a technique that uses measurement of radioactive decay to figure out the age of archaeological artifacts and dinosaur fossils.

Decay and Dating

At the center of every atom is a dense region called a nucleus, which consists of protons and neutrons. In some atoms, the forces in the nucleus are balanced and the nucleus is stable. In others, the forces are unbalanced and the nucleus has an excess of internal energy; it’s unstable, or radioactive. These unstable atoms essentially self-destruct because of the imbalance and break down, or decay. When they do this, they lose energy by emitting energetic subatomic particles (radiation).

These particles can be detected, typically with a Geiger counter. In the case of radiocarbon dating, a common dating method for organic matter that uses carbon-14 (an isotope, or variant, of the element carbon) to estimate age, one radioactive “beta particle” is produced for every carbon-14 atom that decays. By comparing the normal abundance of carbon-14 in a living creature (which is the same concentration in the atmosphere) with the amount left in the material being dated, based on the known decay rate, scientists can figure out roughly how long ago whatever they’re looking at was still alive.

Half-life steps onto the scene in the decay process. While the lifespan of any individual atom is random and unpredictable, the probability of decay is constant. You can’t predict when an unstable atom will break down, but if you have a group of them, you can predict how long it will take. Atoms that have an equal probability of decaying will do so at an exponential rate. That is, the rate of decay will slow in proportion to the amount of radioactive material you have.

“Many will disappear early on in the process but some will last for much longer time periods,” says Dr. Michael Dee, a researcher at Oxford University’s radiocarbon lab. “It’s a bit like putting (a lot) of coins out in the rain. Although they all have an equal probability of being hit by raindrops, many will be struck immediately and others will remain dry, perhaps for an extended period of time.”

It’s easy misinterpret half-life to mean “one half of the time it takes for whatever atoms you’re looking at to decay,” but it actually means “the length of time it takes for one half of the atoms you’re looking at to decay.” The measurement is useful in radiometric dating, says Dee, because exponential decay means “it doesn’t matter how much radioactive material you have, the time taken until half of it is gone [the half-life] is always the same.”

The whole life of the material, on the other hand, would be equal to the lifespan of the last atom in the group to decay. Since an atom’s lifespan is random, inestimable and essentially infinite, the whole life would be, too. It winds up being a not-very-useful measurement. “It’s a bit like one coin sitting out in the rain,” says Dee. “And never getting hit, ever.”

10 Wireless Chargers Designed to Make Life Easier

La Lucia/Moshi
La Lucia/Moshi

While our smart devices and gadgets are necessary in our everyday life, the worst part is the clumsy collection of cords and chargers that go along with them. Thankfully, there are more streamlined ways to keep your phone, AirPods, Apple Watch, and other electronics powered-up. Check out these 10 wireless chargers that are designed to make your life convenient and connected.

1. Otto Q Wireless Fast Charging Pad; $40

Otto Q Wireless Fast Charging Pad
Moshi

Touted as one of the world's fastest chargers, this wireless model from Moshi is ideal for anyone looking to power-up their phone or AirPods in a hurry. It sports a soft, cushioned design and features a proprietary Q-coil module that allows it to charge through a case as thick as 5mm.

Buy it: Mental Floss Shop

2. Gotek Wireless Charging Music Station; $57

Gotek Wireless Charging Music Station
Rego Tech

Consolidate your bedside table with this clock, Bluetooth 5.0 speaker, and wireless charger, all in one. It comes with a built-in radio and glossy LED display with three levels of brightness to suit your style.

Buy it: Mental Floss Shop

3. BentoStack PowerHub 5000; $100 (37 percent off)

BentoStack PowerHub 5000
Function101

This compact Apple accessory organizer will wirelessly charge, port, and store your device accessories in one compact hub. It stacks to look neat and keep you from losing another small piece of equipment.

Buy it: Mental Floss Shop

4. Porto Q 5K Portable Battery with Built-in Wireless Charger; $85

Porto Q 5K Portable Battery with Built-in Wireless Charger
Moshi

This wireless charger doubles as a portable battery, so when your charge dies, the backup battery will double your device’s life. Your friends will love being able to borrow a charge, too, with the easy, non-slip hook-up.

Buy it: Mental Floss Shop

5. 4-in-1 Versatile Wireless Charger; $41 (31 percent off)

4-in-1 Versatile Wireless Charger
La Lucia

Put all of those tangled cords to rest with this single, temperature-controlled charging stand that can work on four devices at once. It even has a built-in safeguard to protect against overcharging.

Buy it: Mental Floss Shop

6. GRAVITIS™ Wireless Car Charger; $20 (31 percent off)

GRAVITIS™ Wireless Car Charger
Origaudio

If you need to charge your phone while also using it as a GPS, this wireless device hooks right into the car’s air vent for safe visibility. Your device will be fully charged within two to three hours, making it perfect for road trips.

Buy it: Mental Floss Shop

7. Futura X Wireless 15W Fast Charging Pad; $35 (30 percent off)

Futura X Wireless 15W Fast Charging Pad
Bezalel

This incredibly thin, tiny charger is designed for anyone looking to declutter their desk or nightstand. Using a USB-C cord for a power source, this wireless charger features a built-in cooling system and is simple to set up—once plugged in, you just have to rest your phone on top to get it working.

Buy it: Mental Floss Shop

8. Apple Watch Wireless Charger Keychain; $20 (59 percent off)

Apple Watch Wireless Charger Keychain
Go Gadgets

This Apple Watch charger is all about convenience on the go. Simply attach the charger to your keys or backpack and wrap your Apple Watch around its magnetic center ring. The whole thing is small enough to be easily carried with you wherever you're traveling, whether you're commuting or out on a day trip.

Buy it: Mental Floss Shop

9. Wireless Charger with 30W Power Delivery & 18W Fast Charger Ports; $55 (38 percent off)

Wireless Charger from TechSmarter
TechSmarter

Fuel up to three devices at once, including a laptop, with this single unit. It can wirelessly charge or hook up to USB and USB-C to consolidate your charging station.

Buy it: Mental Floss Shop

10. FurniQi Bamboo Wireless Charging Side Table; $150 (24 percent off)

FurniQi Bamboo Wireless Charging Side Table
FoneSalesman

This bamboo table is actually a wireless charger—all you have to do is set your device down on the designated charging spot and you're good to go. Easy to construct and completely discreet, this is a novel way to charge your device while entertaining guests or just enjoying your morning coffee.

Buy it: Mental Floss Shop

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What Should You Do In the Unlikely Event You Meet An Alien?

If you ever find yourself in a Mac and Me-type situation, it's best to know what to do.
If you ever find yourself in a Mac and Me-type situation, it's best to know what to do.
Shout! Factory

What do you do if you encounter an alien? It’s obviously fairly unlikely, but nothing is impossible—after all, you can’t spell meet without ET. If there’s a stray dog in your backyard, there’s a set procedure to follow. But what if, rather than a mere hound, it’s a creature from another world?

“If you meet an alien in your backyard, my recommendation is to get out of town,” Seth Shostak, senior astronomer at the SETI Institute, an organization seeking to explore, understand, and explain the origin and nature of life in the universe, tells Mental Floss. “If they have the technology to come here, they’re so far beyond us that whatever they want to do, they're going to do. If they’re here to take over the planet, it’s going to be pretty hard to stop them.”

A creature from another planet lurking on your property means not only that there is intelligent life elsewhere, but that it is at a significantly more technologically advanced stage than humanity. A species with the ability to not only travel the enormous distances involved (the closest star to our sun, which does have some potentially life-supporting planets, is 4.2 light years away), but also land undetected in your flowerbed would simply have us outclassed.

As you flee, however, you might want to contact the emergency services. If, for instance, the alien is aflame—and given that we know nothing about what form such a creature might take, there’s no real reason it wouldn’t be—you might want to give the fire department a call, for example. Moving up a notch, the FBI and Department of Defense are frequently contacted with flying saucer sightings, as are the UK’s Royal Air Force and Ministry of Defence and, well, pretty much every other emergency service in every country. This is because there is no set protocol, no universally agreed-upon decree of exactly what to do in the event of a close encounter.

“As far as I know, there is no policy for that, because that would be like Neanderthals having a policy for if the U.S. military decided to take them on,” Shostak says. “If aliens were actually landing here, we could have whatever policy we wanted and it wouldn’t be likely to help much.”

A scene from E.T.
Universal Pictures Home Entertainment

Whatever Hollywood might tell us, the likelihood is that any contact we have with beings from another world will be limited to picking up a signal from deep space, rather than encountering the long fingers and warm heart of a charming 3-foot-tall alien rustling around in shrubbery. As luck would have it, there is a protocol for that; it's known as the Declaration of Principles Concerning Activities Following the Detection of Extraterrestrial Intelligence [PDF] and was put together by the International Academy of Astronautics with input from Shostak.

The protocols are also entirely voluntary, with no force of law behind them and nobody under any obligation to adhere to them. What if you don’t want to tell everybody? What if you fancy keeping information about life beyond Earth to yourself for a while? You’re the one talking to aliens, after all—surely you can make a few bucks out of the situation ...

As Shostak points out, this kind of thinking is unlikely to get you anywhere. Given the distances involved, and the power required to transmit information that far, you aren’t going to be in any kind of dialogue. Secondly, revealing that you have detected a transmission is useless without it being verified and studied—the process of which, by necessity, involves making that information available to the world. Thirdly, interpreting any alien message will be a mammoth task involving a lot of work from a lot of people, a task unlikely to ever reach a definitive conclusion. “It would depend on whether they were trying to make it easy,” Shostak says.

Anything you discovered would belong to humanity as a whole, as we collectively tried to figure out what the signal meant, both literally and existentially, knowing we are not alone in the universe. You’d get to be the first person to prove there was intelligent life beyond Earth, which might be mildly less exciting in the short term than getting attacked by a little green man while taking the trash out, but at least you’d live to tell the tale.