Physicists Believe They Have Solved Proton Size Mystery

In recent experiments, scientists studied the size of the proton in hydrogen atoms. They used a vacuum chamber to carry out their work.

In 2010, researchers reported the proton’s radius as 0.84 femtometers. A femtometer is very small—it is one million-billionth of a meter. Later tests with heavy particles called muons confirmed this size. However, other studies gave different results.

For example, in 2018, another experiment showed a larger size. In 2019, scientists from York University measured the proton again and found it to be 0.833 femtometers. This matched the earlier 2010 result.

Now, two new studies have confirmed the proton’s size once more. They used lasers to control electrons and measured energy changes. These studies also show the proton is about 0.84 femtometers.

Experts say these results should be the same no matter how scientists measure the proton. This makes the new findings important because they support the original 2010 measurement.

How much do you know?

What did researchers report the proton's radius as in 2010?

0.84 femtometers

0.833 femtometers

1.00 femtometers

0.5 femtometers

What is a femtometer?

One million-billionth of a meter

One billionth of a meter

One trillionth of a meter

One hundredth of a meter

In what year did scientists from York University measure the proton and find it to be 0.833 femtometers?

2010

2018

2019

2020

What technique did the two new studies use to confirm the proton's size?

Vacuum chamber

Lasers to control electrons

Heavy particles

Chemical reactions

Which particles confirmed the proton's size in later tests?

Electrons

Photons

Muons

Neutrons

What is the proton's size as confirmed by multiple studies?

0.5 femtometers

0.84 femtometers

0.833 femtometers

0.9 femtometers

The proton's radius was reported as 0.84 femtometers in 2015.

True False

The studies used lasers to control protons.

True False

Two new studies confirmed the proton's size once more.

True False

The results of measuring the proton's size should vary based on the method used.

True False

In 2018, an experiment showed a larger size for the proton.

True False

A femtometer is a very large measurement.

True False

Researchers reported the proton's radius as 0.84 femtometers in .

A femtometer is one million-billionth of a .

The proton was measured again by scientists from York University in .

Two new studies confirmed the proton's size as approximately 0.84 .

Muons are heavy particles used to test the proton's .

Experts believe the results should be the regardless of measurement method.

This question is required