ZEUS's thunderbolt

 kw: articles, lasers, record setting

An article yesterday in earth.com reports on a record-setting power level for "the most powerful U.S. laser," named ZEUS: 2 petawatts peak power in a pulse lasting 25 quintillionths of a second. The click-bait headline states "over 100x the global electricity output." Let's unpack this a little for us mere mortals.

The author helpfully states that 2 petawatts is 2 quadrillion watts. Firstly, assuming a "square" pulse (it isn't, but probably close enough), 2 quadrillion watts times 25 quintillionths of a second results in 50/1,000ths, or 1/20th, of a watt-second. A watt-second is also known as a Joule, the standard unit of energy. The night light in my hallway uses 0.25 watts, continuously. The energy of this laser pulse would keep my night light shining for…one-fifth of a second. Barely the blink of an eye! What gives?

The breakthrough this article reports is not the sheer power of the pulse. A 0.05 Joule pulse is nothing special. Off-the-shelf metal-cutting lasers operate in the range of 30 J per pulse, ten pulses per second, for an average power of 300 watts. The pulses are short, in the nanosecond to microsecond range, but nowhere near as short as the 25-attosecond  pulse width of the ZEUS laser.

The breakthrough in pulse width is important because it enables the achievement of extreme power levels (such as petawatts), which, I am informed by the Duck Duck Go "AI Assistant", "…enables the study of complex interactions between light and matter, such as astrophysical phenomena and particle acceleration. These powerful lasers are also used in various fields, including medical treatments and material science research."

De-jargonizing that, it says that materials behave differently when hit that hard, and quantum particles such as electrons can be accelerated to extreme energies without resorting to miles-wide accelerators. The "astrophysical phenomena" mentioned include the very high energy environments found near black holes or during supernova eruptions.

Now that scientists have squeezed a modest-energy pulse into one forty-thousandth of a trillionth of a second, I expect further work will lead to much greater total power and peak power.