Scientists can levitate stuff and make it fly around using sound

Japanese scientists have made hundreds of tiny plastic balls float around like miniature spaceships.

Today’s news from the world of Awesome Science comes from the University of Tokyo, where a team has been levitating and controlling objects using sound. Here’s the video:

As the video points out at the beginning, levitation of objects using sound has been around for a few years. If you’ve ever stood in front of a large speaker you’ll know that they can pump out what feels like quite a forceful blast of air as they vibrate - but, somewhat deceptively, that’s not quite the whole story.

Rather than physically push air out from the speaker, what you’re experiencing is a wave of compression moving through the air. The speaker compresses a packet of air, which then “rolls” through the room, with the size of the compressed air corresponding the wavelength of the sound wave. And, just like sound waves, waves that overlap each other create new waves.

To levitate something just requires creating a standing wave. Think of it like this - if you’re watching a sound wave plotted out on a graph, it’ll be rolling along, going up and down as it oscillates. A standing wave occurs when two or more waves combine to create a new wave where, as the wave oscillates, there are points where there’s no movement. They’re called nodes.

Here’s a gif to illustrate how that works. The blue and green waves are combining to create the red wave, which has those points on the central axis that aren’t moving:

(Image: Wikimedia Commons)

If a speaker outputs a standing wave, in the most basic sense it means that it won’t feel like the areas of compression - those blasts of air - are moving. The gaps between those blasts of air will be positions of neutral force, with air pressure pushing in on it from both directions. If you stick an object in there that’s light enough, and smaller that the size the gap (which will be the sound’s wavelength), the force of the air should keep it floating in a stable position.

What the Tokyo University team has done is build upon that idea, by combining sound waves in three dimensions. The video shows not just tiny little plastic balls being levitated and controlled, but also resistors, LEDs, screws, bolts, and other small items. Rhett Allain at Wired worked out that you could levitate anything both smaller than 8mm and less dense than 1,000kg/m3, which is tiny - but it does have practical applications, particularly when people are working with sterile things they want to move but can't touch, like spaceship parts or medicines.

Ian Steadman is a staff science and technology writer at the New Statesman. He is on Twitter as @iansteadman.

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"It's just a prank, bro": inside YouTube’s most twisted genre

Despite endless headlines and media scrutiny, catchphrases such as "it was a social experiment" and "block the haters" have allowed YouTube's dangerous pranking culture to continue unregulated.

A year and five months after the worst prank video ever was uploaded to the internet, its crown has been usurped. In November 2015, YouTuber Sam Pepper made headlines after he filmed a video entitled “KILLING BEST FRIEND PRANK”. In the video, Pepper kidnaps a man before forcing him to watch his friend be “murdered” by a masked figure. Rocking on the chair he has been tied to, the victim sobs and shouts: “We’re just kids”.

Last week, an actual child – aged nine – was victim to a similarly distressing “prank”. Michael and Heather Martin, of the YouTube channel DaddyOFive, poured disappearing ink on to their son Cody’s carpet before – in Heather’s words – “flipping out” on the child.

“What the fuck did you do,” yells Heather to summon Cody to his room. “I swear to God I didn’t do that,” screams and cries Cody as his parents verbally berate him. His face goes red; he falls to his knees.

You won’t find either of these videos on either of their creators’ channels today. After considerable backlash, Pepper deleted his video and DaddyOFive have now made all of their videos (bar one) private. The Martins have faced international scrutiny after being called out by prominent YouTuber Philip DeFranco, who collated a video of clips in which Cody is “pranked” by his family. In one, Cody appears to be pushed face-first into a bookcase by his father. In another, a visibly distressed Cody sobs while his father says: “It’s just a prank bro.”

These five words have been used to justify some of the most heinous pranks in YouTube history. Sam Pepper famously called a video in which he pinched the bottoms of unsuspecting women, a “social experiment”. Usually, though, creators’ excuses follow a pattern. “It was just a prank,” they say. Then, if the heat doesn't subside: “Actually, it was fake.”

Three months after his “KILLING BEST FRIEND” prank, Pepper claimed the video – and all of his other prank videos – were staged. In a video entitled “Family Destroyed Over False Aquisations [sic]” the Martins have now also claimed that their videos are scripted. “We act them out,” says Michael. It seems many on the internet remain sceptical. The Child Protection Services website for Maryland – where the Martins live – has crashed after Redditors encouraged one another to report the family. If the Martins’ videos are indeed staged, Cody is one of the shining child actors of our time.

Though the Martins might yet face severe consequences for their pranks, it wouldn’t be surprising if they didn’t.  The “Just a prank”/“No it’s fake” cycle means that despite multiple headline-grabbing backlashes, YouTube pranking culture continues to thrive. Boyfriends pretend to throw their girlfriend’s cats out windows; fathers pretend to mothers that their sons have died. YouTubers deliberately step on strangers' feet in order to provoke fights. Sometimes, yes, pranksters are arrested for faking robberies, but in the meantime their subscribers continue to grow in their millions.

At present, there is no regulatory body that examines YouTube. Pranksters who break the law are arrested, but children whose daily lives are filmed for the site are not protected by the same regulations that safeguard child actors from being overworked or exploited. Though the communications authority Ofcom has guidelines about wind-up calls and consent, it does not regulate YouTube. The BBC were famously fined £150,000 by the body after Russell Brand and Jonathon Ross prank called Andrew Sachs, yet internet pranks remain out of its jurisdiction.

Though YouTube removes videos that breach its “Community Guidelines”, it seems illogical that we trust the service to police itself. Since the invention of the radio, we have assumed that independent bodies are needed to scrutinise the media – so why you should the largest video-sharing platform on the planet be exempt? No one is truly looking out for either the pranking victims or the children of YouTube. God forbid, like Cody, if you are both.

It is also arguable that YouTube pranks need more regulation than those broadcast on TV. Britain’s favourite pranking shows revolve around humiliating comedians themselves – Trigger Happy TV, Balls of Steel, Jackass – or are very soft (think a man pretending to be both a mime and a policeman) in nature. When someone is outright humiliated on TV, it’s because they are seen to be “fair game”, such as in Comedy Central’s Fameless Prankers, where people desperate to be famous are forced into increasingly humiliating situations. On YouTube, there are no consent forms or waivers to ensure filming remains ethical, and YouTube pranksters often target more vulnerable people.

“There’s an element of power here with the parents and it seems this is very top-down,” says Jonathan Wynn, a sociology professor at the University of Massachusetts who has written on pranks in the past. Wynn explains that traditionally pranks mock status and hierarchy, such as when court jesters taunted kings. When pranks come from the top down, Wynn says they allow a group to bond emotionally – arguably something the Martins are attempting as a family. Nonetheless, Wynn notes this would work better if the children also pranked their parents equally. “In this case the status differential is quite high, when you have children and parents.”

Traditionally, the mainstream media has had little room for this type of content. In 2012, two radio DJs attempted to prank the Duchess of Cambridge Kate Middleton by calling the hospital she was staying at, but instead tricked two nurses. When one of these nurses, Jacintha Saldanha, died by suicide days later, the episode seemed the ultimate illustration of the recklessness of pranks that “punch down”.

Conversely, status differentials are a large part of YouTube prank culture. Rather than attacking people in power, YouTube pranks are often played by those in power (the YouTube famous) on those who have lower social status. Frequently, boyfriends prank girlfriends, for example, and since 2014, white pranksters have filmed “in the hood” pranks provoking young black men. In “The N Word Prank!!” famous internet prankster Roman Atwood goes around saying “What’s up my neighbour” to people of colour, knowing that it will be misheard as a racial slur. In the context of this pranking culture, a parent pranking a child to the point of tears seems almost inevitable.

Perhaps, then, it is easy to understand why Michael and Heather Martin “prank” their children – it is harder to understand why anyone is watching. The DaddyOFive channel has over 750,000 subscribers, with over 7,000 of these subscribing after Philip DeFranco’s video accused the family of “abusing” their children. In order to defend themselves, the Martins initially employed another YouTube rhetoric, on top of “just a prank bro”. In a since deleted video, they invited their fans to “block the haters”.

This phrase is ingrained in online culture, and has allowed internet celebrities to dismiss criticism for years. By painting anyone who is critical as “jealous” or a “hater”, YouTubers can ensure their fans ignore their words and therefore stay loyal. In a video response to Philip DeFranco, the Martins riffed off a popular meme and placed spoons over their eyes to symbolise this mentality, and now fans as young as 12 are copying this action to show their support. When I search the hashtag used by the family’s supporters to see if anyone might be willing to explain why they still love the channel, I am faced with the reality that most of DaddyOFive’s fans are children. Though YouTube’s minimum sign-up age is 13, there is nothing really stopping children from watching – and normalising – harmful content, particularly when it is disguised as a “prank”.

In this context, it doesn’t matter in the slightest whether a prank is faked. Sam Pepper might have asked his friend's permission before he fake-kidnapped him, and perhaps Michael Martin was only pretending when he pushed his son into a bookcase. Neither of these facts will prevent children – 19 percent of whom have a desire to be famous – from copying these actions in order to promote their own YouTube channels. Even if a YouTuber is punished for a dangerous pranking video, there are thousands of other pranksters ready and willing to take their place.

It remains to be seen whether the Martins will continue with their YouTube channel. At the end of their now infamous invisible ink prank, Michael asks Cody to “do the outro” – the concluding section of a YouTube video. Wiping his nose and still red in the face, Cody rattles off his script at alarming speed.“Thank you guys for watching this video if you like this video and want to see more videos like this one leave a comment down the section below and don’t forget to follow us on Twitter, Instagram, Facebook, Snapchat… and don’t forget to… Like and Subscribe.”

Since the backlash, Michael has added a new line into the “About” section of the DaddyOFive YouTube channel. After reiterating that the videos are fake, he writes: “no child was harmed in the making of our videos”.

Amelia Tait is a technology and digital culture writer at the New Statesman.

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