Sounds of Science #04

Dark Energy

So most of our universe (over 70%) is made up of something called Dark Energy. We can't see it and we don't really know what it is...

Matter - everything that makes up me, you, planets and stars - appears to make up only a very small fraction of the universe, about 4%. Instead, the universe seems to be filled predominantly by a very strange material known as dark energy and it is this material, with it's anti-gravity properties, which seems to speeding up the expansion of our universe. We've known that the universe was expanding since Edwin Hubble made his observations in the 1920s, however it's only in the last 20 years that we've realised that this expansion is actually speeding up! The problem is that we can't directly detect dark energy and this makes it very difficult to understand what it is and whether it really does exist.

Instead we must rely on indirect observations, looking at light travelling from the far reaches of the universe to determine whether the properties of this light has changed during the time it has taken to reach us. A good way to measure the expanding universe is to make observations of distant supernovae (huge explosions which follow the death of large stars) which act as 'standard candles' or 'lighthouses' because we know how bright these object should be. Measuring light from distant supernovae has allowed us to see that it is different to what it should be if these objects were positioned within a static universe. Instead what we see is changes in this light which indicates that these objects are being flung outwards and away from us via some sort of cosmic expansion.

A nice analogy to describe the expansion of the universe is what happens when two points are drawn on the surface of an inflating balloon. As the balloon is inflated, the two points begin to move further and further away from each other and as the material expands outwards, the distance between the two points also increases. Applying this analogy to the cosmos, we could imagine the same happening with two galaxies being pulled apart from each other as the space they exist in expands.

As dark energy is so difficult to detect, scientists have recently been looking for new ways to independently verify its presence within the universe. Whilst at the BBC I was lucky enough to interview cosmologist Dr Chris Blake from Swinburne University, Australia who has recently published two papers reconfirming dark energy via a new set of methods. Blake and his colleagues produced a galaxy map of over 200,000 galaxies and used this information to look at how these galaxies were distributed and how they grew relative to each other. Through this work Blake and his colleagues were able to reconfirm the presence of dark energy and perhaps most importantly were able to determine some of its properties.

I thought I'd use the audio from this telephone interview and spruce it for the next sounds of science episode:

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It probably sounds better with headphones (or obviously decent speakers).

Useful links:

Not bad for an old man... (Apollo 14)

Continuing the Apollo 14 coverage - I was inspired to create a short radio piece on the mission which was broadcast on our 'Science @ 1' show earlier today. Check it out: [soundcloud width="100%" height="81" params="" url=""]

[Update 03/05/11]

This segment was included on Short Science_89


"It looks like you’re about on the bottom step... and on the surface."

"Not bad for an old man."

- Mission Control referring to Alan Shepard as he first stepped out onto the moon's surface. At the age of 47, Shepard was the oldest man to ever walk on the moon.


I went to a very interesting night (run by Super Collider) on Monday evening which celebrated the 40th anniversary of the Apollo 14 lunar mission with a talk from Dr Christopher Riley – a broadcaster and expert on all things Apollo. Dr Riley also launched his new video installation entitled ‘Cone Crater’ - which I believe is showing throughout February at the Book Club in Shoreditch.

I must admit I knew very little about the story of Apollo 14, which turns out to be pretty interesting so I'll fill you in on some of the details...

Apollo 14 was the eighth manned mission in the Apollo program and the third to take men to the moon. The nine day mission took Commander Alan Shepard, Command Module Pilot Stuart Roosa and Lunar Module Pilot Edgar Mitchell to the moon after taking off from the Kennedy Space Centre on January 31st, 1971. Five days later Shepard and Mitchell landed on the moon in their Lunar Module whilst Roosa remained alone in orbit, aboard the Command Module.

The lunar landing was slightly stressful...

1) Firstly during the descent the Lunar Module computer went a bit squiff doo and started to receive an ABORT signal, which nearly initiated an auto-abort of the landing. This would have separated the ascent component of the Lunar Module from the descent component taking the crew back into orbit and thus cancelling a very expensive trip to the moon (not ideal). This was only corrected at the last minute, with Mitchell having to manually persuade the computer (inputting a software patch) to ignore the erroneous signal.

2) As if that wasn't enough, the Lunar Module radar altimeter (I definitely know what this is) failed to lock onto the moons surface, which would usually be pretty hard to miss – this was determined to be a consequence of the earlier software updates (was Microsoft involved?). To remedy this, the crew basically did what you might have done when your computer breaks - they unplugged it; then plugged it back in; only it actually worked.

During their stay on the moon (clocking in at about 33 hours) Shepard and Mitchell went out on two moon walks, the second of which they got very lost on. They attempted to navigate to the rim of a 300m wide crater but instead spent most of the time not actually finding it, so in the end they had to turn back - it turns out they got within 3om of it! In addition to this they also found time to fit in a spot of golf and with a make shift six-iron, Shepard managed to single-handedly (the suits were pretty cumbersome) dispatch two golf balls into the moon’s horizon.

The crew returned to Earth safely, dropping down in the Pacific Ocean on February 9th. During the mission Roosa had brought with him several hundred seeds which on return were planted as commemorative ‘moon trees’ across America. Apollo 14 also clocked up the longest distance traversed by foot on the lunar surface and was the first to utilise colour TV on the moon.

I left the talk in a state of wonder and with a sense of awe at the achievements of the Apollo missions - we'd put men on the moon (and filmed it!) before an age of portable computers, mobile phones and digital cameras. However, I couldn't help but feel slightly dejected by the current state of space exploration, especially with the planned retirement of NASAs shuttle program later this year. I wonder whether I will ever see images beamed back of someone walking on the surface of another world - sadly I very much doubt it.

I'll finish this post with one of my favourite videos - a live performance of Brian Eno's Apollo music (which was created specifically for the documentary 'For All Mankind' - check it out!) this, if anything is enough to keep me wishing for a future in space.