Those hungry for answers to the mysteries of the cosmos gathered at the Skirball Centre in New York on Thursday night to learn about the dark side of the universe. The aim of this spectacularly engaging production was to discover more about the unknowns of the universe, with a panel consisting of some of the world’s leading researchers in the fields of physics and cosmology. The focus of this sold-out event was a topic which proves most mysterious to physicists: dark matter and dark energy….

This may sound sinister, but co-founder and executive director of the WSF, Brian Green, lightened the mood by introducing the audience to this enigmatic subject with a “physics” rendition of Jimmy Buffett’s Dark Side of the Moon.

With the audience excitable and geared up for an adventure out of this world, Brian revealed an unfathomable fact; despite everything we understand about the universe, scientists are still left in the dark about 96% of what is out there.

Brian Greene introducing the concept of dark matter

It is assumed that 73% of the universe is made of dark energy, and 23 % of dark matter; however, we do not fully understand what they are. Brian reveals that when someone does figure it out, they will be sure to make a trip to Stockholm!

The intersection of science and art meeting

Attempting to explain something that is invisible is a daunting task, yet today’s discussion aimed to do so, or at least to explain the theories underpinning these claims by addressing a range of questions. What is this dark stuff? How do we know it’s there? And what does it do?

Dancer-illusionists, Momix, known internationally for presenting work of exceptional inventiveness and physical beauty, opened the show with a mesmerizing performance. This unusually enchanting act, which mixed darkness and light, beautifully illustrated that the things we do see can be affected by the things we don’t. You can watch their performance and the whole event in the recording.

Dark matter Vs Dark Energy

Award winning journalist, John Hockenberry, who acted as moderator of the debate, opened up the floor by introducing us to the two teams:

Fighting in the Dark Matter corner were the all-female physicists, Katherine Freese, Elena Aprile and Glennys Farrar.

In contention, the Dark Energy team was made up of all-male physicists, Michael Turner, Saul Perlmutter and Brain Greene.

Dark Matter opens

Glennys Farrar, Professor of Physics at New York University, kicked off the debate by explaining what these unseen masses could be. Elena Aprile moved onto an explanation of how to design an experiment to detect dark matter. She revealed the workings behind her Xenon100 detector, which aims to measure WIMPs – Weak Interacting Massive Particles – hypothetical particles which serve as one possible solution to the dark matter problem.

The all-female dark matter team tried to answer questions such as, “Where do we go in the universe for direct evidence of dark matter?” As well as exploring the edges of the known universe in search of clues to nature’s dark side. Katherine Freese revealed that once the James Webb telescope is developed it may help prove the existence of dark matter. Finally the team revealed that dark energy is repulsive and dark matter is attractive and that “without dark matter, you would not be here today.”

The dark matter team certainly put up a fight. Next the floor opened up to the dark energy team…

Dark Energy

Michael Turner, the theoretical cosmologist from the University of Chicago who actually coined the term “dark energy”, began their argument by revealing that:

… nothing is something. It is repulsive gravity; we call this stuff dark energy.

Saul Perlmutter then continues on from this statement by explaining his research which could suggest the existence of dark energy. When examining the expansion of the universe one would expect that, because galaxies are rushing away from us, the measurable rate of this (according to gravity) should be slower. Saul and his team at Berkley’s Department of Physics, whilst working on the Supernova Cosmology Project which aims to measure the expansion history of the universe, discovered something quite shocking. The universe is moving away from us faster than we ever imagined. John Hockenberry interjects here asking the question we all wanted to know:

Will Saul Perlmutter get a nobel prize for discovering the universes stretch marks?

Saul explains that this is inline with Einstein’s predictions; dark energy has a repulsive push that gravity does not have. Gravity depends only on the mass of an object, not the material it makes up, but what Einstein proposed was that dark energy is defined by the material as well as the mass. Dark energy has a negative, repulsive gravity and the only thing in the universe we know that has this is the energy of nothing.

Cosmology was at a crossroads and Saul explains that we know the universe is accelerating due to the repulsive nature of dark energy. If this concept wasn’t baffling enough, Brian Greene then goes on to explain how string theory fits into this.

Finally

The debate squares off as John asks both teams how long it will be until their theories are proven scientifically:

Katherine Freese – Dark matter will be defined in the next decade. The next generation of telescopes has a shot at this.

Saul Perlmutter – Dark energy will be defined in the next 20 years (15 years for the data and 5 for the Aaahaa moment)

Brian Green – I will give you my answer at the next World Science Festival…

So who do you think won the argument? Your answer will mean nothing…….or will it…..?

If you want to read more highlights from the World Science Festival, you can find a summary of all our coverage here.