light

Electromagnetic radiation in the wavelength range visible to the human eye (about 400–750 nanometers): visible light.

As you can see, this spacious dining-room gets a lot of light in the mornings.

Then came a maid with hand-bag and shawls, and after her a tall young lady. She stood for a moment holding her skirt above the grimy steps,[…], and the light of the reflector fell full upon her.

Electromagnetic radiation in the wavelength range visible to the human eye or in nearby ranges (infrared or ultraviolet radiation).

black light

Electromagnetic radiation of any wavelength.

It’s everywhere. At this moment, as you sit quietly reading this book, you are awash in it. At work, it’s emanating from your electronic devices; step outside for lunch, and the sun bathes you in it. You may receive an extra dose of it when you visit your doctor, pass through security at the airport, or drive through city streets, but minuscule amounts of it are with you always. You cannot see, hear, smell, or feel it, but there is never a single second when it is not flying through your body. Too much of it will kill you, but without it you wouldn’t live a year. “Invisible light” seems like a contradiction. Like Simon and Garfunkel’s “The Sound of Silence,” it’s an oxymoron. We think of light, by definition, as something seen, something that enables our seeing, illuminating the darkness. Unlike dogs, who sniff in order to “get” what an object is, we depend on vision above all our other senses. We rely on light to tell us about our surroundings. But just as there are frequencies of sound audible to other animals that we cannot hear, there is a whole world of light outside our range of vision, a world that is humming with activity. Though we rarely think about this invisible world, our way of life depends on it. It’s because of invisible light that you can do things such as send a text message, use GPS to find your way to a friend’s house, listen to the radio, or microwave a frozen pizza. Invisible light shows us things we would never otherwise see, including our own skeletons and brains and the history of our universe. I was reminded of just how much we rely on invisible light, and how mysterious it remains to us, during a visit from my sister and her family. It was a lazy summer afternoon, and we were sprawled across a few couches sharing a bowl of popcorn. My niece, her shoulders crimson after a day outdoors, was chatting on her cell phone, holding up a promising finger to her mother, who was scolding her for not using sunscreen. My brother-in-law, meanwhile, was asking my opinion on an article he’d read proposing that Wi-Fi be banned in schools because of its dangers. We were all depending on invisible light (for the microwave popcorn, the cell-phone service) while being concerned that it might harm us (sunburn, mysterious Wi-Fi health threats) and confused about what to do to protect ourselves. We need it, and it surrounds us, yet we remain uneasy about living with invisible light, partly because we fear what is unknown. After all, most of us don’t know much about “all the light we cannot see.” This book aims to change that. My hope is to expose the hidden side of the spectrum, to make the invisible (at least temporarily) visible and vivid to you.

A source of illumination.

Put that light out!

And the light ſhineth in darkneſſe, and the darkneſſe compꝛehended it not.

A source of illumination.

We turned off all the lights and went to sleep.

The ceiling lights were off, but I knew the narrow light spilling from the lamp on my bureau would be enough for her to see the pale red marks on my chest, which had been fading for so long they had gone back to being shiny again.

To start (a fire).

We lit the fire to get some heat.

To set fire to; to set burning.

She lit her last match.

if a thousand candles be all lighted from one

To illuminate; to provide light for when it is dark.

I used my torch to light the way home through the woods in the night.

19th century', Frederic Harrison, The Fortnightly Review One hundred years ago, to have lit this theatre as brilliantly as it is now lighted would have cost, I suppose, fifty pounds.

To become ignited; to take fire.

This soggy match will not light.

To attend or conduct with a light; to show the way to by means of a light.

His bishops lead him forth, and light him on.

Having light; bright; clear; not dark or obscure.

The room is light when the Sun shines through the window.

Historic England explained the listing: "The station's unique design employs a high level of sophistication and innovation through its use of conoid shells supported on a cruck-like frame, which not only create a dramatic aesthetic form, but endow the building with a light and spacious interior."

Pale or whitish in color; highly luminous and more or less deficient in chroma.

She had light skin.

'Twas early June, the new grass was flourishing everywheres, the posies in the yard—peonies and such—in full bloom, the Sun was shining, and the water of the bay was blue, with light green streaks where the shoal showed.

Served with extra milk or cream.

I like my coffee light.