What goes 'pop' when we crack our knuckles?

Gregory Kawchuk, a University of Alberta researcher, along with his colleagues, has revealed what makes our knuckles crack by clicking the joints of one of their team inside an MRI scanner.

The researchers captured three images per second inside the scanner as they tugged on a rope attached to the index finger of their volunteer. They were able to capture what happened inside the knuckle joint at the precise moment when it went crack.

The Naked Scientist, Chris Smith, explained to CapeTalk/702's Redi Tlhabi what the research revealed:

They have revealed that the noise, when we crack our knuckles, is a bubble of gas appearing under low pressure, in the joint - and that what makes the sound.

The Naked Scientist, Chris Smith

Previous theories on why our knuckles crack:

  • In 1947, two UK scientists speculated that joints click and crack when low-pressure triggers a bubble to pop into existence inside the joint space.

  • In the 1970s, a second group of British researchers instead claimed that the sound was produced, not by a bubble forming in the joint, but instead when it collapsed in on itself afterwards. This is a process called cavitation, and it became the benchmark explanation for why joints crack.

Scientists had no direct observations to support either theory, according to Smith.

Listen to the full conversation on the Redi Tlhabi Show:

Read More
Jay Naidoo: Organised communities have the power to create change

Jay Naidoo: Organised communities have the power to create change

Social activist Jay Naidoo has written a book which explores the power of human connection and social activism.

Local bee farming company Native Nosi creating a buzz with raw honey

Local bee farming company Native Nosi creating a buzz with raw honey

Native Nosi owner Mokgadi Mabela says over 50% of honey sold in SA is imported and she wants to change the business landscape.

How do we ensure the safety of women in South Africa?

How do we ensure the safety of women in South Africa?

Women's Legal Centre and POWA discuss ways to ensuring the legal system stops failing women of South Africa.

Visual activists use work to highlight realities of women, LGBTI communities

Visual activists use work to highlight realities of women, LGBTI communities

Acclaimed photographer Zanele Muholi and curator Lerato Dumse discuss to exhibitions of work and the power of visual activism.

The Naked Scientist unpacks the physics of popcorn

The Naked Scientist unpacks the physics of popcorn

Armed with a packet of popcorn, a high speed camera and a hotplate, scientists have found why, how and when kernels of corn pop.

Blood tests could predict surgery recovery time.

Blood tests could predict surgery recovery time.

Redi spoke to The Naked Scientist about how blood tests could predict how long patients could take to recover post surgery.

Popular articles
It's not the end of the road... Top tips to improve your matric

It's not the end of the road... Top tips to improve your matric

"Recognise that it’s not the end, it’s the beginning." Expert advise for school-leavers who want to improve their results.

Pamela Nomvete on her downfalls as actress, and 'climbing back'

Pamela Nomvete on her downfalls as actress, and 'climbing back'

This week Xolani Gwala's speaks to former Generations actor Pamela Nomvete for #WhatInTheWorldHappenedTo feature.

Meet the founder of Capitec Bank, named ‘Best Bank on Earth and Cheapest in SA’

Meet the founder of Capitec Bank, named ‘Best Bank on Earth and Cheapest in SA’

Michiel le Roux speaks about the fascinating story behind the little bank that has the Big 4 shaking in their boots.

Best way to get richer (especially if you’re between ages 20 and 45)

Best way to get richer (especially if you’re between ages 20 and 45)

Still young(ish)? Consider the single best thing you can do to increase your wealth by much more than the inflation rate.

3 easy questions could bag you R2000!

3 easy questions could bag you R2000!

WIN R2000! But only if you can prove you're a whiz of the MTN Biz Quiz by answering the following three questions...

Blesserfinder: Matching you with a sugar daddy near you

Blesserfinder: Matching you with a sugar daddy near you

Is social trend Blesserfinder, where girls are allegedly matching up with rich 'benefactors' in exchange for sex, a real thing?

5 ways the NSFAS funding model will change in 2017

5 ways the NSFAS funding model will change in 2017

The National Student Financial Aid Scheme (NSFAS) will pilot a new funding model in 2017. NSFAS chairperson Sizwe Nxasana explains.