The next television you buy won’t contain a cathode-ray tube. And thanks to the imminent worldwide transition from analog to digital television, you probably will be buying a new TV soon--you and more than a billion other consumers around the world.

With the United States going fully digital in 2009 and other developed countries following closely on its heels, the entire television landscape will change dramatically in the next few years. What technology will dominate this new TV world? It will be flat, that’s for sure. All the new television technologies vying to dethrone the clunky, 100-year-old CRT are sleek and thin.

But will it be plasma, liquid crystal, or one of several new technologies not yet on retail shelves? Will they all survive, or do some of them have intrinsic technical weaknesses that will doom them in the next five or six years? I’m going to tell you where I’m placing my bets, but first, I’ll look at all the horses in this race.

Today, plasma televisions are what many consumers would like to have hanging on their walls; liquid-crystal-display televisions are what they can afford. Both are flat-screen systems with picture quality that, when displaying high-definition video, rivals film’s. Prices for both have dropped dramatically in the past few years; a 42-inch-diagonal plasma set that includes a tuner sells for about US $2000 today, compared with $5000 just four years ago. A 37-inch LCD set, a more popular size for that technology, runs about $1200.

This year, nearly 8 million plasma TVs will be manufactured worldwide, according to Gartner Dataquest--a unit of Gartner, headquartered in Stamford, Conn.--nearly double 2005’s production. Gartner estimates that LCD manufacturing plants will have rolled out nearly 42 million of those popular television displays by year-end. The vast majority of these sets, plasma and LCD alike, are produced in Japan, Korea, and Taiwan.

Both plasma and LCD TVs can have considerably bigger screens than CRTs can, but plasma screens can be absolutely huge: the largest screens available today measure 102 inches diagonally. Plasma images are also fairly bright and can be viewed clearly from virtually any angle. Today’s LCDs have a wider viewing angle than earlier models, but the field of view is still not quite as wide as that of other technologies.

Nevertheless, a plasma TV won’t be the last TV you buy. Here’s why: it’s got limited longevity, it’s power hungry, and it’s heavy. Like CRTs, plasma displays use red, green, and blue phosphors, but instead of hitting the phosphors directly with a beam of electrons, as in a CRT, a plasma display charges pockets of xenon and neon gas trapped between two glass panels with a honeycomb of cells.

In essence, every plasma display contains about a million miniature fluorescent tubes, evenly divided among red, green, and blue. When the charged, or ionized, gas releases ultraviolet photons, these photons strike the phosphors, which, in turn, emit the colored light that produces the television picture.

The longevity problem comes from the fact that the light-emitting efficiency of the phosphor coating decreases over time--that is, when a phosphor is stimulated by a photon, it releases less and less light. The problem is much worse in a plasma set than in a CRT because the plasma’s phosphors exist in a hostile environment; the electron beam in a CRT is much kinder to phosphors than are a plasma’s hot gases. In a plasma display, the contrast ratio--the difference between lit and unlit picture elements--drops quickly under normal use, as much as 50 percent in four to five years. At that point, the television image appears noticeably washed-out.

Manufacturers today claim 60 000 hours of use before the brightness falls by half (based on a few hundred hours of testing). Contrast, however, is more important than brightness. Recent tests by market research firm IDC, in Framingham, Mass., measured a 13 percent decline in the darkness of the black of a typical plasma television after four weeks of use; after five years of use, such a rapid decline could lead to blacks displaying as light grays.

Plasma displays also consume more power. Even though manufacturers have reduced the power consumption of typical plasma technology by 30 percent over the past five years, these units continue to need more power than comparable LCD TVs, particularly when displaying a white or light screen. This power consumption generates heat; if the sets are not cooled properly, heat build-up can damage components. Before you buy a plasma TV, consider this fact: Philips sent repair technicians to 12 000 U.S. homes this past spring to replace components in plasma TVs that could potentially overheat.

Plasma displays are also heavier than their flat-panel competitors. Because the glass panels that surround the gas are much thicker in plasma displays, a 40-inch plasma set weighs 43 kilograms, while the same-size flat-panel set weighs just 25 kg. Plasma technology requires such thick glass because the gas is very hot; thin glass would simply melt.

There are other problems, too, such as burn-in. It’s a particular problem nowadays because with 1000-channel cable and satellite services, TV networks feel an acute need to identify themselves all the time, usually with a static channel logo in the lower part of the screen. Again, because plasma technology is harder on phosphors than CRT technology is, burn-in happens faster and is more noticeable on plasma televisions. Manufacturers have done a lot to deal with this problem, and on new plasma sets, after approximately 12 hours of use without the static image, the burn-in will fade away. But it is still a drawback.

And as if those problems weren’t enough, plasma sets also don’t work well at high altitudes or, indeed, in any place where the ambient pressure is different from that of their internal gases. When such a differential exists, the TV’s power supply has to work harder to keep the gases ionized.

To be sure, plasma manufacturers have worked hard to address the technology’s deficiencies. They have developed ­longer-life phosphors, and they have made great strides in controlling light leakage between cells, successfully displaying darker blacks. But plasma sets with these improvements cost significantly more than competing LCD sets. And in any case, ordinary consumers are mostly buying the cheaper sets, in which the problems remain.