Astronomy

The Gravitational Constant is Tricky to pin Down Accurately. Here’s a new way to Measure it

A team of physicists have used a pair of vibrating rods to measure the gravitational constant to incredibly fine precision. While the new technique has relatively high uncertainty, they hope that future improvements will provide a new pathway to nailing down this elusive constant.

The gravitational constant, denoted as G, is the fundamental building block of our understanding of gravity. Isaac Newton first introduced the constant into his equations when he developed his universal theory of gravitation over 300 years ago.

The constant tells us the fundamental strength of gravity, or the strength of the gravitational attraction between two objects a certain distance apart and with given masses. We cannot calculate the value of this constant from any theory. We can only discover it through measurement and experimentation.

But since gravity is by far the weakest of the forces, our knowledge of the value of the gravitational constant is relatively imprecise.

“The only option for resolving this situation is to measure the gravitational constant with as many different methods as possible,” explains Jürg Dual, a professor in the Department of Mechanical and Process Engineering at ETH Zurich. Dual led a team to develop a new method for measuring the gravitational constant.

Dual and his team started with a suspended metal bar. They then vibrated the bar and measured how much an adjacent bar also vibrated. The two bars weren’t touching. Instead, as the first bar vibrated it emitted gravitational waves that set the other bar in motion.

This is a new way of measuring the gravitational constant that relies on a dynamical system rather than a static one. With static systems you also have to contend with the gravitational influence of literally everything else in the universe. With a dynamical system the physicists were much better able to isolate their measurement.

The measurement of the gravitational constant that the team produced is about 2.2% higher than the currently accepted value, but it does have a large uncertainty. “To obtain a reliable value, we still need to reduce this uncertainty by a considerable amount. We’re already in the process of taking measurements with a slightly modified experimental setup so that we can determine the constant with even greater precision,” explained Dual.

Dual and his team hope that the new technique will pay off, providing a completely independent measurement of the gravitational constant. An improved measurement will help physicists understand everything from gravitational waves emitted by distant black holes to the fundamental nature of gravity itself.

Paul M. Sutter

Astrophysicist, Author, Host | pmsutter.com

Recent Posts

NASA Tests the New Starship Docking System

The Apollo Program delivered 12 American astronauts to the surface of the Moon. But that…

3 hours ago

China Has Built a Huge Space Simulation Chamber

Well it certainly caught my attention when I saw the headlines  “China’s first Space Environment…

8 hours ago

The International Space Station’s Air Leaks are Increasing. No Danger to the Crew

Only the other week I had to fix my leaky tap. That was a nightmare. …

9 hours ago

Planetary Atmospheres: Why study them? What can they teach us about finding life beyond Earth?

Universe Today has surveyed the importance of studying impact craters, planetary surfaces, exoplanets, astrobiology, solar…

17 hours ago

How Startups on Earth Could Blaze a Trail for Cities on Mars

If future explorers manage to set up communities on Mars, how will they pay their…

23 hours ago

This Planet-Forming Disk has More Water Than Earth’s Oceans

Astronomers have detected a large amount of water vapour in the protoplanetary disk around a…

23 hours ago