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
No surprise that Nzimande shown the door in Cabinet reshuffle - analyst

No surprise that Nzimande shown the door in Cabinet reshuffle - analyst

Political analyst Karima Brown says SACP members who remain in Cabinet are "at the mercy" of Zuma and will have to strategise.

How we invented the modern concept of sleep

How we invented the modern concept of sleep

Dr Bodhisattva Kar reveals how industrial capitalism influenced the world's current sleep patterns.

Where are the whites at DA led marches?

Where are the whites at DA led marches?

DA's Makashule Gana penned an article in which he responds to journo Karyn Maughan's criticism of the party's marches.

Zuma SCA judgment: Everything you need to know

Zuma SCA judgment: Everything you need to know

Advocate James Grant provides pithy analysis on SCA decision that withdrawing charges against President Jacob Zuma was irrational.

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
Why Sisulu and Dlamini-Zuma aren't suitable Presidential candidates: analyst

Why Sisulu and Dlamini-Zuma aren't suitable Presidential candidates: analyst

ANC branch in the Eastern Cape, Z.R Mahabana, has launched a campaign backing Lindiwe Sisuslu as an ANC presidential candidate.

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.

Gospel singer Sipho Makhabane explains how Sfiso Ncwane died

Gospel singer Sipho Makhabane explains how Sfiso Ncwane died

Makhabane says Ncwane was feeling weak yesterday and his wife phoned paramedics to check on him.

14 job titles that callers can't take seriously

14 job titles that callers can't take seriously

People do some very interesting things for a living, but some job titles are given more credit than others.

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.

Who is Advocate Tembeka Ngcukaitobi?

Who is Advocate Tembeka Ngcukaitobi?

The EFF lawyer stole the show during the state capture report court battle.

‘I started my thriving business with R5000 (and made a profit in the 1st month)’

‘I started my thriving business with R5000 (and made a profit in the 1st month)’

After 3 years there are 3 Nic Harry stores (incl online) that sell 100 000 pairs of socks in over 20 countries around the world.

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?