Dark skies: a view of the milky way during a meteor shower, Myanmar. Photo: Getty
Show Hide image

Dark energy vs dark matter: a battle of two cosmic monsters

Michael Brooks’s Science Column.

It might be the most prestigious journal in physics, but the Physical Review Letters is no good at teasers. Early in November it published a paper entitled: Indications of a Late-Time Interaction in the Dark Sector. Hardly a great headline for what should have been, in the style of Alien v Predator, “Dark Matter v Dark Energy” – a story of two cosmic monsters locked in eternal conflict.

We believe these monsters exist, but we haven’t seen either of them and we know very little about them. We have suspected the existence of dark matter since 1933, when a Swiss astronomer noticed something odd about the way galaxy clusters spin. They looked like they were being held together by the gravitational pull of invisible matter, which he duly named dark matter. We have been trying to see the stuff ever since, to no avail.

Dark energy is a more recent idea. It, too, comes from astronomical observations, this time of supernovae. A 1998 analysis of the light from these stellar explosions suggested that not only is the universe expanding, but this expansion is getting faster all the time. That can only happen with the help of energy from some unknown source – hence dark energy.

Together, dark energy and dark matter make up 96 per cent of the universe. Now, it turns out, dark energy may be consuming the dark matter.

The discovery came from more observations: this time, of the rate at which cosmic structures form. Dark matter seeds galaxy formation, but galaxies aren’t forming as fast as we would expect. This would make sense if dark matter were disappearing from the universe, but various straightforward explanations for why that might occur have failed to correspond with the observed facts. Now a team of British and Italian researchers has created a computer model that does match the observations. Critical to its success is the idea that dark matter is slowly being converted to dark energy.

According to the simulation, the ingestion of dark matter would be a relatively recent phenomenon, beginning roughly eight billion years ago. If it is really happening, it is important to understand, because our attempts to chart the history of the universe depend on dark matter’s role in forming cosmic structures.

Working from observations of the cosmic microwave background radiation, which came into being roughly 300,000 years after the Big Bang, researchers have shown that the radiation’s distribution through the universe would have seeded long filaments of dark matter. The gravitational pull of these filaments attracted the first atoms of normal matter, gradually creating stars and galaxies in long strings. This is the kind of structure we see now.

Yet if dark energy is slowly taking over from dark matter our previous calculations of cosmic history will have to be corrected. And intriguingly (spoiler alert), it will change our predictions. If dark energy is consuming dark matter, the universe will become dominated by dark energy more quickly than previously thought. That will precipitate an inglorious finale in which dark energy’s repulsive power pushes everything interesting away from us.

Eventually, all the other galaxies will be so far away, and receding so fast, that their light will never reach what remains of our Milky Way. Nearby stars will burn out. Our sun is expected to end its life as a huge single crystal of carbon: a dark diamond in the sky, with no surrounding starlight to make it sparkle.

Afterwards, all the atoms will drift apart and then the fundamental particles of matter will slowly decay to nothing. It’s not a Hollywood ending, but don’t complain that you weren’t warned. 

Michael Brooks holds a PhD in quantum physics. He writes a weekly science column for the New Statesman, and his most recent book is At the Edge of Uncertainty: 11 Discoveries Taking Science by Surprise.

This article first appeared in the 27 November 2014 issue of the New Statesman, The rise of the insurgents

PewDiePie
Show Hide image

"Death to all Jews": Why Disney dropped YouTube's biggest star PewDiePie

The Minecraft vlogger turned internet celebrity's taste for shock comedy was too much for the family-focused corporation. 

Disney has cut ties with YouTube’s most-subscribed star after he paid two Sri Lankan men five dollars to hold up a sign that read “DEATH TO ALL JEWS”.

Feel free to read that sentence again, it’s not going anywhere.

A still from PewDiePie's video, via YouTube

PewDiePie, real name Felix Kjellberg, has over 53 million subscribers on YouTube, where his videos about gaming earned him over $15m last year. The 27-year-old, whose content is popular with children, came under fire this month after the Wall Street Journal investigated anti-Semitic comments in his videos. In one video, a man dressed as Jesus says “Hitler did absolutely nothing wrong”, while in another Kjellberg used freelance marketplace Fiverr to pay two men to hold up the offensive sign. The videos have since been deleted.

Jumpcut.

The Walt Disney Company became affiliated with PewDiePie after they bought Maker Studios, a network of YouTube stars, for nearly $1bn in 2014. Following the WSJ’s investigation, Maker dropped the star, stating: “Although Felix has created a following by being provocative and irreverent, he clearly went too far in this case and the resulting videos are inappropriate. Maker Studios has made the decision to end our affiliation with him going forward.”

When you sack a YouTube Star, makes no difference who they are.

Via Wall Street Journal

But why should the story stop there? Neo-nazi website The Daily Stormer are now defending PewDiePie, while the notoriously politically-incorrect 4Chan forum /pol/ have called him “our guy”.  

In his defence, Kjellberg wrote a blog post denying an affiliation with anti-Semitic groups and explained his actions, writing: “I was trying to show how crazy the modern world is, specifically some of the services available online.” In a video last December the star also said: "It's extremely annoying how I can't make jokes on my channel without anyone quoting it as actual facts, like something I actually said", before dressing as a soldier and listening to one of Hitler's speeches while smiling. 

Pause.

(If all of this sounds familiar, recall when disgraced YouTuber Sam Pepper claimed a video in which he groped unsuspecting females was a “social experiment”).

Play.

And yet the story still isn’t over. Disney have learned a hard lesson about assuming that YouTubers are the squeaky clean fairy-tale princes and princesses they often appear to be. Shay Butler, one of the original founders of Maker Studios, yesterday quit the internet after it was alleged he sent sexual messages to a cam girl via Twitter.

Butler is one of the original "family vloggers", and has spent nine years uploading daily videos of his five children to YouTube. A practicing Mormon, Butler has become emblematic of family values on the site. “My heart is sick,” he wrote on Twitter, neither confirming nor denying the allegations of his infidelity, “I have struggled with alcoholism for years… My purpose is to rehab.” 

The result is a very dark day for YouTube, which has now dropped Kjellberg from its premier advertising network, Google Preferred, and cancelled the second series of the star's reality show, Scare PewDiePie

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