In the world of electronics, the term “aspect ratio” refers to the shape of your screen. Today's high-definition television picture has a 16:9 aspect ratio—a rectangle with those proportions. The older, standard TV picture had a 4:3 aspect ratio—not quite square but squarish. Films, IMAX movies and photographs all have aspect-ratio standards of their own.

This cacophony of conflicting shapes can lead to some ugly results. Remember watching widescreen movies on standard TVs? Much of your screen was filled by horizontal, black “letterbox” bars above and below the picture. And on high-def TVs, watching old shows requires big, black “pillarbox” bars on either side of the square picture.

If that seemed confusing, though, don't look now, because we've just entered the age of aspect-ratio hell.

The culprit is smartphones. We now watch more video on our mobile gadgets than we do on TVs and computers. And guess what? A phone's screen has portrait orientation—a tall, thin rectangle. It's the worst possible shape for showing wide (landscape-orientation) images. Movies and TV shows play as a tiny slit of screen on an ocean of black.

I know what you're screaming: “But we can turn the phone 90 degrees, numbskull!” Yes, we can. But we don't. There's a certain hassle, an inconvenience, a discomfort, in turning your phone. You move from One-Hand Land to Two-Hand Land. Fewer and fewer people bother turning their phones to watch widescreen videos—72 percent of millennials don't, in fact.

Software and video producers are scrambling to accommodate the New Normal—the vertical-aspect-ratio screen. Snapchat started it; its 178 million fans overwhelmingly take and share vertically shot photos and videos. Facebook now presents vertical videos in your scrolling feed without your having to tap to expand them; advertisers report that their vertical Facebook ads get much more attention from viewers than square ones. Instagram, YouTube and Twitter have updated their apps to handle vertical videos, too.

Professional outfits are now shooting vertically to match the trend. Vervid is a new app that exists purely to play vertical videos. Vertical Cinema ( is a vertical-video film festival, in which the movie screen is hung vertically. Yahoo (my employer) is developing a new subscription service whose shows are all shot vertically. The upshot: Because of their ubiquity, we now watch most of our videos on smartphones; because of ergonomics, we hold the phone vertically; because we hold it that way, professional videos are now being produced to match. Okay, great.

But all of this leaves us in a massive aspect-ratio pickle. Our TVs and computer screens are still horizontal. So what happens when a vertical cellphone video plays on a TV or a laptop? You've surely seen it: broadcasters gamely try to fill the empty pillarbox areas with blurry copies of the main video. It's awful. Conversely, the entire archive of movies and hi-def TV is horizontal. Those videos will never look even close to right on vertical screens.

Then there's the issue of what's in the videos. Fans of vertical video argue that vertical shots do better justice to buildings, trees, mountains and scenes of a single upright person. Instead of just head and shoulders, you're seeing torso and hands, too.

There's a good reason our standards for movies and TV are horizontal: our eyes are arranged horizontally, and we spend our lives on a horizontal plane. A horizontal format is far superior to vertical at showing most things in daily life. For example, scenes with more than one person and just about anything in motion.

In other words, we're witnessing a titanic crash between our eyes and our hands, between logic and ergonomics, between the old and the new. What's the resolution? Young people will never turn their phones sideways; on the other hand, TVs, movie theaters and computer screens won't soon be designed vertically. This isn't a temporary transitional problem, either, as it was when we moved from standard to hi-def TV; this time the two formats will have to coexist. For once, it's easy to predict the shape(s) of things to come—and it's kind of a mess.