Placeholder Image

Subtitles section Play video

  • It really is kind of a mad scientist atmosphere when you're essentially blowing

  • things up, and it's all legal.

  • It's like Dr. Frankenstein came back to life.

  • He would be running a lab like this.

  • If he could really bring things back to life with intense energy, this would be the place.

  • Astrophysicist Mike Montgomery is talking about the Z Machine -- one of the most powerful

  • devices on Earth,

  • capable of firing more than 20 MEGAJOULES of energy at a tiny target at its center. It's

  • used to uncover some of the greatest mysteries of our universe.

  • So there's an enormous release of energy.

  • And in just a few nanoseconds, you release more energy than five times all the power

  • plants on the Earth.

  • It's an incredible powerful thing, it's the most powerful X-ray source on planet Earth

  • by a lot.

  • When it goes off, there's an enormous boom.

  • You feel it move through you, the doors vibrate, the ground shakes.

  • The Z Machine is helping drive innovation in the fields of radiation sciences, material

  • sciences, and fusion studies.

  • Even redefining the field of astronomy by making experimentation possible.

  • We can actually create the cosmic conditions in the laboratory.

  • Now we can turn astronomy into an experimental science like physics or any other science.

  • Always before we say, well it's an observational science.

  • And we go out to McDonald Observatory.

  • But now we go to Sandia National Labs and do these experiments and create those conditions.

  • Don Winget and Mike Montgomery from the University of Texas at Austin are here to fire the Z

  • and create conditions similar to the interior of a star. The stakes are very high -- because,

  • the Z shots are very precious.

  • There's one a day at Sandia, basically, at most.

  • So you only get a very precious handful of shots.

  • If you're the white dwarf experiment, you may only get something like 15 of these shots

  • a year -- if you're lucky.

  • You realize you're using something very few people are privileged to be able to use to

  • do something that's very rare and very special.

  • You don't want to lose one because you didn't hook up a cable correctly.

  • Or because something wasn't aligned perfectly.

  • And you don't want to lose a shot because a leak is making it impossible to create a

  • vacuum in the experiment chamber.

  • Unfortunately, this is the scenario Mike, Don, and the Z Team currently face.

  • More than 16 hours have passed since yesterday's scheduled shot and technicians have finally

  • located the leak.

  • They work quickly and carefully to seal it.

  • The care that has to be taken with the entire operation at Z is a little like the US Space program.

  • In the space program they're doing hard things, and they're doing hard things that can't go wrong.

  • It gives you a tremendous amount of respect for the team that does it, you realize that

  • this is a very special operation and that they're highly skilled, and it's an amazing instrument.

  • And so I'm delighted to be able to take part in an actual laboratory experiment, which

  • I didn't really think was going to happen in my astronomy career.

  • Mike and Don have spent decades observing and studying white dwarf stars.

  • Now, they'll get the chance to recreate one on Earth.

  • As we look at our Milky Way we look at say, a couple hundred billion stars.

  • Most of those stars, about 97% plus, almost 98% we think will become white dwarf stars.

  • White dwarfs are the burnt out cores of red giant stars -- but I hate describing

  • them that way.

  • White dwarfs are the natural endpoint for most stars.

  • Once they become a white dwarf they're fossil remnants of stars.

  • They're finally a stable form.

  • And because white dwarfs are typically the oldest celestial bodies in their star systems,

  • they've been used as reliable timekeepers of the cosmos.

  • An age is one of the hardest things to determine.

  • You can't measure an age.

  • It's a derived quantity.

  • You can measure how bright something is or how far away it is, but without a model for

  • how that object changes with time, you cannot measure an age.

  • To break this down further -- we can measure a star's brightness using powerful telescopes.

  • These powerful telescopes record visible spectra that provide clues about a star's composition

  • and temperature.

  • Each element has a fingerprint that's unique to that element, and so that tells you what

  • elements are present.

  • So you break the light apart into its colors and you look for the signature of these elements,

  • and the relative strengths of the various lines that you see contains information about

  • the temperature.

  • Visible spectra can also be used to determine a star's mass.

  • All this information can be used to create cooling models to determine a star's age.

  • You've got a block of iron, and you've been heating it in the

  • fire up to 800 or 1,000 degrees, and you take it out, and you measure its temperature versus

  • time, it just gets cooler and cooler.

  • It's not that hard to calculate how fast it should get cooler and cooler either.

  • So, with the white dwarf, it's the same thing.

  • Astrophysicists like Mike and Don can then use the oldest white dwarfs to estimate the

  • age of other celestial bodies, galaxies, and even the universe itself.

  • The research that Don did back in the late '80s showed that you could use these coolest

  • white dwarfs to figure out how old the disk of our galaxy is.

  • Don's groundbreaking work not only resulted in recalibrating the age of the Milky Way

  • -- but also resulted in adjusting the estimated age of our universe from roughly 20 billion

  • years to 13 billion years.

  • But what if those models used to determine the age of white dwarfs still aren't quite right?

  • We knew that there was physics yet to be understood in the white dwarf spectra.

  • So we've started to realize we're having systematic problems

  • with that, so that the spectroscopic values of the mass that we're deriving may have systematic

  • problems of 10% errors in mass.

  • It could be larger.

  • For those who haven't yet done the math -- a 10% error on 13 BILLION means the current

  • estimated age of the universe could be off by MORE THAN A BILLION YEARS!

  • And that's why we're now trying to do experiments on Earth which will nail down these problems.

  • With the leak sealed and the Experiment Chamber pumped down to create the necessary vacuum,

  • all systems are go for fire.

  • Here we go!

  • With this shot, the Z Machine will recreate the conditions of the interior of a star allowing

  • researchers to examine the properties of plasma x-rays and investigate how hydrogen atoms

  • absorb light.

  • Unfortunately, due to safety protocol, our cameras aren't allowed beyond these doors.

  • Charge complete.

  • Ready to fire.

  • Yeahhh!

  • I saw a flash!

  • In astronomy, we wait for the universe to make the experiment and then we look at the

  • results, but we can't ask nature to repeat the experiment.

  • Almost every one of you guys jumped!

  • We did not jump.

  • We reacted.

  • Now we have a real laboratory so it just leverages how much more information we can get from

  • astrophysical objects if we can calibrate the models that we're using to interpret them.

  • Now the rest of the data will come out; it'll percolate out over the course of the next

  • 24 hours, but now we know that the experiment was successful.

  • And that's the whole idea, benchmarking the observations and the theory, benchmarking

  • the theory that's used to create the models through which we interpret the observations.

  • Astronomy is great and it has all these pretty pictures, but it's really understanding the

  • pretty pictures, that's the fun part.

It really is kind of a mad scientist atmosphere when you're essentially blowing

Subtitles and vocabulary

Click the word to look it up Click the word to find further inforamtion about it