This seems a peculiar question, but astrophysicists and cosmologists have been trying to weigh space for decades.
Another seemingly peculiar question, is empty space empty? Well, that one appears to be moot. Our current state of understanding says no, even a perfect vacuum is not empty. That’s a pretty strong statement, but that’s the accepted notion of space. So, even the emptiest space has something in it.
That something, don’t get mad, is called virtual particles. Wait, isn’t virtual a pretend thing, not actual? Virtual is the best description our science can conjure for this phenomenon. Why? Because they are of the enigmatic quantum world and the term virtual fits right in. Dutch physicist Hendrik Casimir postulated in 1948 how to detect the presence of virtual particles, but we didn’t have the technology until 1997 to test it. Physicist Steven Lamoreaux at the University of Washington confirmed Casimir’s postulate. How? Two metal plates in a vacuum were adjusted so they were close enough to each other that the space did not allow photons of longer wavelengths to fit between. That’s super close! The result was fewer photons inside the space than outside, and like air pressure, the outside photons pressure was higher and that was measurable. Now it’s called the Casimir Effect. That’s weird – wild stuff!
Our universe, on the subatomic level, is a Magical Mystery Tour. The Beatles would have had fun with virtual particles.
Getting back to the weight of space, this has avoided scrutiny and probably caused some angst among physicists of all stripes. Oh, I didn’t mention, according to theory, virtual particles pop in and out of existence constantly. Try weighing a cat when dozens are continuously hopping on and off the scale. It’s a problem.
Back up you say, why is knowing what space weighs so important? Don’t these people have more important things to worry about? Look at these people. Probably took physics in high school, got a PhD in physics, maybe specialized while in college. They live for the challenges of understanding the mysteries of everything. I appreciate this because their esoteric work might eventually weave itself into important applied technologies. Perhaps Earth saving technologies. I would have enjoyed being a physicist, but oh, except for the math. Never mind.
Determining what space weighs might be a Rosetta stone find. Many scientists think knowing this will help answer questions concerning dark energy and matter, the nature of gravity, and ultimately understanding the expansion of out universe.
How to weigh space? Enter the Archimedes Experiment. In 2002 Enrico Calloni formed a team to investigate the possibility. The result, the Archimedes Experiment, involves setting up two massive, exquisitely sensitive balance beams, inside a vacuum, inside a deep cave in Sardinia, one of the most seismically quiet places on Earth. Their instruments will use technology like the gravitational wave detectors in VIRGO. In one balance they will induce the Casimir Effect and try to measure the difference.
Good luck Archimedes!
What’s in the Sky?
May 5 – Full Moon (Flower, Planting, Frog, Egg Laying, Shedding Ponies Moon)