Of course, since this object has not cleared its orbit, I suppose it must actually be an exodwarfplanet.

Dark Matter & Dark Energy - [Read More about Dark Matter and Dark Energy]

Dark matter is hypothetical matter that feels no effect from electromagnetism, so we cannot see it. Its presence can only be inferred by the gravitational influence it exerts. Galaxy’s do not rotate as expected from Newtonian dyanamics. The Coma cluster of galaxies also has properites that gravity cannot explain.

Dark energy is similarly mysterious but even less easy to understand. It is a kind of energy that permeates the whole universe, driving it apart and causing it to expand. These two things together purportedly make up 96% of the content of the Universe.

Physical cosmologists study dark matter and dark energy with great interest. Change their names to ‘gravity not doing it what it should’ and things can look slightly different. A branch of physics labelled MOND (MOdified Newtonian Dynamics) tries to explain the observational evidence without adding in unknown forms of matter and energy. There are also many scientists who feel that ‘dark energy’ gives the wrong impresion and that this stuff might be normal matter that we simply don’t see for some reason.

So either gravity is wrong or matter is. That is quite a dilemma for astrophysicists to resolve.

Gravitational Waves - [Read More about Gravitational Waves]

Now, I’ve gotten in trouble before for having a beef with gravitational waves, so I’ll try to be kinder here. Gravitational waves are fluctuations in the curvature of spacetime which transmit the energy of gravity and propagate its effects through the universe. Light’s energy is transmitted to us by fluctuations in the electromagnetic field, this would be an alternative spectrum of waves, detectable by completely different means.

The study of gravitational waves has received a nobel prize (1993, I think?) when they were indirectly detected in a binary system containing a pulsar. The orbital energy in the binary system was seen to decay in exact accordance with the theories of gravitational wave physics.

Einstein’s general relativity explains gravitational waves very well  - in fact if gravitational waves don’t exists there is a big problem. The problem comes along when you find out that no one has ever detected a gravitational wave. People have been trying for quite some time.

I often see graphs which explain this lack of detection. Basically gravity waves may just be too subtle to be detected by current methods. The answer is to build larger, more complicated observatories (in space preferably). The plans are already made. If they don’t find them then, either a new idea gets floated, or a new graph gets drawn and an even bigger detector is created.

I hope they find them before too much money gets spent!

The Higgs Boson - [Read More about the Higgs Boson]

The Large Hadron Collider (LHC) had to be shut down for a little while and so its main target: the Higgs Boson remains an unknown and unverifiable character.

Imagine you had a really nice cake. You studied this cake for a long time and you managed to figure out exactly how it was made. You could tell me the proportions and nature of the original ingredients, the length of time for which it was baked even the exact colourings used in the icing. What you don’t know though, is the type of spoon that the cook used. Without knowing this you will never truly have understood how the cake was made - and you will never managed to recreate it. If it turns out that there was no spoon then your whole theory falls apart!

The Higgs Boson is that spoon.

Without the Higgs Boson the whole framework of our understanding of particle physics is incomplete. The LHC should be able to detect it. If it can’t, then there may be a problem and the standard model of patricles will need to be reconsidered. If it is found then we would have a complete understanding of the particles that make up the Universe. That would be profound and powerful. We may find out one way or the other in 2009.

Panspermia - [Read More about Panspermia]

How did life on Earth begin? Well one ides is that it came to our little rock from space. This notion is called Panspermia and it is actually as old as modern science. Early musings on evolution in the 18th Century considered that the original germs came from space.

Fred Hoyle (who died in 2001) and Chandra Wickramasinghe (who is now based in Cardiff’s astrobiology centre) were early proponents of Panspermia in its modern form. They also suggested that lifeforms continue to enter the Earth’s atmosphere, and that they might still cause epidemics and provide new genetic material for the planet.

The problem with Panspermia is that it solves a complicated problem (how did life spontaneously begin on Earth) with an even more complicated one (how did life spontaneously begin elsewhere and then travel across billions of miles of interstellar space). For this reason, many need a lot of convincing about the idea.

String Theory - [Read More about String Theory]

String Theory is the name given to a branch of physics and maths that aims to describe the Universe in terms of multi-dimensional vibrating strings. No this isn’t Pratchett. It would be a way to combine the as-yet irreconcilable theories of quantum mechanics and general relativity - this is something of a holy grail in modern physics.

String theory is a broad name for a collection of theories - some of which disagree with each other - but all of which boil down to the principle described above. The trick is, you cannot disprove string theory. You would need an experiment so large and powerful that it would require orders of scale larger than our Solar System. We are a very, very long way from achieving this.

The strings themselves would be so fantastically small as to be possibly prohibited from measurement by nature itself. Lengths and timescales so minute that we could never measure them.

One hope for string theory is that we may see evidence of hidden dimensions when the LHC begins operations. However this could also be evidence of other things, and not necessarily but a win for string theory.

For these reasons, many consider string theory not to be science, but rather mathematics. However, one day in the distant future we build the right apparatus and experimentally test this outlandishly cool idea. It may be right - or it may just be a mathematically self-consistent way to explain particle physics and gravity.

Summary

Popular ideas are not always good ones, nor are they necessarily bad. The work being done to advanced science in the five areas above is extremely important. However so is the work being done to provide alternative ideas and theories. Nothing in science is proven until it is proven.

Protons in 14,000,000,000,000 electron volt collisions

600,000,000 times a second

after travelling 26,659 metres

at 11,245 times a second.

10,080 tonnes of liquid nitrogen cooling

9,300 magnets

controlling collisions at 99.99% the speed of light.

All taking place at -271.3°C

and 10^-13 atmospheres.

It all turns on today with hopes of unravelling the mysteries of spacetime (and not spacetime itself as Radio 2 would have you believe - but as Brian Cox would say, they are “twats”).

Learn more right here.

Flickr user FlintstoneStargazer captured all 110 of the Messier Objects between March 7th and August 6th this year. They have all been compiled into a big mosaic. This is very cool - anyone else ever tried anything like it?

Finally my paper studying the Ophiuchus star-forming region is done and dusted and has been accepted for publication. Thanks to one of my intrepid co-authors, that paper appeared today on astro-ph, the preprint paper listing for astronomy and astrophysical theses.

We re-analyse all of the archive observations of the Ophiuchus dark cloud L1688 that were carried out with the submillimetre common-user bolometer array (SCUBA) at the James Clerk Maxwell Telescope (JCMT). For the first time we put together all of the data that were taken of this cloud at different times to make a deeper map at 850 microns than has ever previously been published. Using this new, deeper map we extract the pre-stellar cores from the data. We use updated values for the distance to the cloud complex, and also for the internal temperatures of the pre-stellar cores to generate an updated core mass function (CMF). This updated CMF is consistent with previous results in so far as they went, but our deeper map gives an improved completeness limit of 0.1 Mo (0.16 Jy), which enables us to show that a turnover exists in the low-mass regime of the CMF. The L1688 CMF shows the same form as the stellar IMF and can be mapped onto the stellar IMF, showing that the IMF is determined at the prestellar core stage. We compare L1688 with the Orion star-forming region and find that the turnover in the L1688 CMF occurs at a mass roughly a factor of two lower than the CMF turnover in Orion. This suggests that the position of the CMF turnover may be a function of environment.

It is a study of star formation and prestellar cores, the objects that precede protostars. You can access the online abstract and get more information at arXiv.org or simply download the PDF from Orbiting Frog.

Black holes are very interesting things, aren’t they? There’s something fascinating about those things which are so hard to understand. Black holes are one of the most asked about objects at almost any public space talk. Certainly school children seem to be obsessed with them!

So a question I was asked this week (by both John and Margaret) was ‘what is the smallest size of a black hole?’. If a star can collapse into a small space and become a black hole, can a planet or even a proton? Well yes, they can, so long as you squash them down hard enough.

There is no theoretical limit on the sizes of black holes. A black hole is determined by how much mass is being contained within a radius. If you put enough material inside a small enough space, you get an object which is so dense that even light cannot escape: a black hole.

Put another way, if you were to squash down any object far enough you eventually get a black hole. This critical size is called the Schwarzschild radius. For example, the Schwarzschild radius for the Sun would be 3km and for the Earth it would be about 9mm. Just imagine compressing the Earth down to just 18mm across!

The follow-up question from John was a great one:

Newton’s olde cannon fired objects toward the horizon at faster and faster speeds until they reached escape velocity and ‘fell’ into orbit. Fair enough, but this idea was never applied to light because light was just too damn fast and also no one believed it was affected by gravity anyway. Now we know better. So does this mean that if a beam of light approached a black hole at precisely the right glancing angle to match its speed that it would not fall in but form a kind of ‘light in orbit’… like saturns rings but made only of light?   

I had never though of this before - which is why I love people sending in questions. So I went to find out from some people who should know, here at the university, whether light could orbit a black hole. The answer surprised me: ‘yes’.

It turns out that light can orbit a black hole, but not for very long. Just beyond the event horizon of a black hole (the distance at which nothing can escape), there is a short distance in which an incident photon is deflected into a circular ‘photon orbit’. It won’t stay very long in this state though. These orbits are highly unstable and soon the photon would either spiral into the black hole’s event horizon or be ejected outward again. I just really like that this can happen, even it happens for a very short time. I wonder what it looks like?

I hope that this is just as interesting for everyone to learn about. If anyone out there knows more on this topic, I’d love to hear from you.

Spectrometers are used, like prisms, to spread light out into the component colours. This enables us to understand the compositions of everything from stars to streetlights. Here I show you how to make your own spectrometer and give you a few examples of what you can see with it.

What You Need:

• A cardboard tube (toilet roll or kitchen roll tubes are just perfect, in the pictures here, I have used more black card to make a tube myself.)
• 2 square pieces of black card (approx 8cm x 8cm)
• Black tape or masking tape (something that blocks out light)
• Razor blades (nothing fancy just cheap blades that are not attached to anything)
• A stanley knife
• An old CD

Make a Diffraction Grating:

Cut a small square hole (approx 1cm across) in the middle of one of your 8cm x 8cm black cards. Break the CD into pieces, just snap it. You’ll need a section of the broken CD that can nicely cover the 1cm hole in your card.

Using a bit of sticky tape, peel away any cover remaining on the piece of CD, so that it is transparent. Use tape to stick it over the hole, creating a sort of window. This will be our diffraction grating.

Make a Very Fine Slit:

Using a stanley knife, cut a slit in the middle of the other piece of 8cm x 8cm black card. This slit should be about 2cm long and just a few millimetres wide. Tape the the two razor blades either side of the slit. They should make an even narrower slit, just 1mm or less if possible!

The aim is create a very fine, narrow slit though which light can travel. Make sure the blades are securely attached with tape for safety.

Make the Spectrometer:

This is the easy bit! You now attach the two square cards to either end of the tube using the dark tape. You have to attach it in such a way that no light is let into the tube accidentally (hence the dark tape). When you look through the diffraction grating, you only want to see light coming from the slit.

Testing Out Your Spectrometer:

The best way to see how this works is to use daylight. Just point the spectrometer toward a window during the day or up at a cloud if you’re outside. You should not ever look directly at the Sun. You should see a nice, smooth spectrum (rainbow) somewhere in your field of view in the tube. Here is a photo of a cloud taken through my own spectrometer. The bright white light is the slit and spectrum is just off to one side.

What’s Happening?

When light enters the tube though the slit it spreads out - all waves do this when passing through small slits. The CD then makes the separate colours visisble to your eye. You see a nice, even spectrum from daylight sources because daylight is made up of all the colours of visible light from the Sun. Once you can see this pattern, you can start trying to find the spectra of other things.

In our physics lab we have lamps of different chemical make-ups. These let us see pure light from different sources. Here are a few I took today, all photos taken by my own camera through my own, homemade spectrometer.

Here is the spectrum for Zinc, which you can see contains some red and blue but very little green.

Cadmium is very distinctive, with short sections of each of the three primary colours and very little between them. It is less spread out than Zinc. There is a big gap between the green and red sections.

Krypton is seen to be fainter than the others here, but the spectrum is still visible. The blue section has become much more violet or indigo here and the green is greener than it was in Cadmium.

The Astronomy Connection:

This is how astronomers know what stars are made of. They use advanced spectrometers to measure the spectrum of stars and pull out the ‘fingerprint’ patterns of colour that you see above. Each element has a unique set of spectral lines (colours) and these can identify the presence of different chemicals in stars, nebulae and just about everything else.

This is the whole spectrum of the Sun. It is so detailed that it had to spread onto multiple lines to see it properly! You’ll see that in fact it is not perfectly evenly spread out as I suggested earlier. This was taken with a very advanced spectrometer that has a greatly increased sensitivity compared to one made here, but its based on the same principles.

Things to Look At With Your Spectrometer:

• Sodium streelights
• Compare daylight to a lightbulb.
• Different light bulbs look different (that’s why energy saving bulbs light up the room in a different way).
• Neon signs.
• TV  and computer screens.
• LEDs from computers or remote controls (these give very pure spectra, often only one colour).

Have fun with your spectrometer and why not try and take a photo through it? It worked fairly well for me. I’d love to see any photos you take with it, or of it. Let me know how you get on. Thanks to the Science Made Simple team for this great idea!

This amazing image was taken using an extremely fast, advanced technology. A short burst of laser light, mere attoseconds long is seen here, weaving its way through the electromagnetic field. Out of this world!

Read More on New Scientist

I found out today that I have annoyed some of my gravity-wave-studying contemporaries with My Beef with Gravity Waves. It got me thinking about gravity waves again and about black holes. I found a website, black-holes.org which has some interesting stuff. One highlight I thought I’d share are the sounds of black holes and other gravitational events.

Gravity waves, like any wave, can be interpreted as sounds and when they are, you get some interesting combinations of clicks and tones. Here are a few of the most interesting ones. Apparently they were all created by Teviet Creighton.

To begin we have the sound of a nice, steady object: a pulsar. These rapidly spinning, neutron stars produce gravity waves with a nice, regular tone. One day, I hope someone creates a gravity-wave telescope/instrument combination using pulsars as the keys.

Download audio file (periodic.mp3)

Two black holes that meet will merge and coalesce into a single, larger black hole. Here’s the sound of just such an event, where each black hole is about ten times as massive as the Sun.

Download audio file (inspiral.mp3)

An extreme mass-ratio binary is a system where two objects orbit each other, but one is far bigger than the other. This type of system is very well understood and takes a long time to evolve and infall. This next sound is that of an extreme mass-ratio black hole binary as it collapses…

Download audio file (extremebh.mp3)

and here is the same kind of event, but with more lead in time. This lets you hear the gradual change of the pitch and the ‘knocking’, as the black holes are drawn slowly closer together.

Download audio file (extremebh2.mp3)

The brightest events in the universe are supernovae: the death of giant stars. This cosmic flash is very different when observed through the microphone of gravity waves. Here is a supernova, blipping out of existence:

Download audio file (supernova.mp3)

Another familar idea seen through an unfamiliar, gravitational lens is that ’sound’ of the early universe. The Big Bang left a kind of echo, which was also represented by a gravtational background noise. If you had been detecting gravity waves during the early life of the universe it would have sounded like white noise.

Download audio file (earlyuniverse.mp3)

Finally, what is actually heard by a gravitational wave detector? They are not yet powerful enough to actually have made any detections because of noise. Like trying to see faint stars with all the street lights on, gravity wave detection suffers the problem of the Earth and its associated tremors. Earthquakes, lorries, even people create quakes and shakes which are confusing to gravity wave detectors. The microphone on a gravity wave detector would actually not hear the crisp tones so far discussed, but would actually hear this:

Download audio file (microphone.mp3)

There’s more to be found on the black holes website, and there will be more here on Orbiting Frog on the matter of gravity waves as soon as I collect my thoughts and actually get some work done!

You learn more about Planck and the LFI and HFI instruments via this link and you can also follow the craft’s Twitter feed. I like this whole Twittering spacecraft thing - its so accessible and easy for anyone. Brilliant.

Oh and did I mention that Cardiff University is heavily involved in Planck, particularly with the HFI instrument which was built here.

People always argue that science and religion do not deal with the same phenomena, or the same aspects of human life. Mang had already done so so in this debate:

“Religion and science fulfill different aspects of human needs. In that sense they are orthogonal or at least do not occupy the same space or set.” - Mang

I disagree with this point entirely. Religion makes scientific claims: miracles, prayer, virgin birth are examples. These are ideas at odds with science and if you take them literally then you must rationalise them as either being metaphors or being against physics or biology. If they are metaphors then your religion is dealt a blow (virgin birth, for example). If they go against physics then they directly contradict science and you have some cognitive dissonance going on!

Religions generally all believe that there is a God or collection of gods in charge of the universe. This is a hypothesis that can be tested in science. If God is ‘up there’ interfering with our daily lives then we should be able to test that. If God set the universe in motion then we will be able to test that at some later time in future history.

You might argue that God is ‘outside testing’. This is surely incorrect since God must act upon things to make things happen. Prayer for example, can be tested and in fact has been. This leads me another point, which is that religion is willing to use science to prove itself.

The idea that religion and science do not overlap in our lives is easily bunked by the existence of prayer experiments, but also by the turin shroud, for example. If someone dug up the body of Jesus would religion back off saying ‘nothing to do with us’? If the prayer experiments had proved that prayer works (they didn’t by the way), then it would have been held aloft as proof of religion working. Rather what we actually have are religious people trying to explain why the experiments wouldn’t work.

Another point to tackle is a response to part of Todd’s comment.

“In many ways religion and science are quite similar: they each define a human culture, they each espouse a certain orthodoxy among adherents, they each inspire passion and sometimes ill feelings between practitioners who don’t operate the same way, they each reveal the best and the worst of human beings.” - Todd

This is true of all human endeavours. It is not something special about science or about religion that creates this similarly, it is something about people. Politics, social clubs, theatre groups, office staff, classrooms and even blogs all have different styles of operation with in-groups and out-groups.

It doesn’t achieve anything to try to say that science is just like religion based on the fact that both operate in similar social ways. They are innately different.

So to finish (for now) I would like to put to it you all that science and religion are incompatible as world views. In our everyday lives, most of us only dabble in the shallow end of theology or of science, never finding a need to really decide between religion and science. I think though, that when faced with the deep questions, you have to choose. Trying to fit both into your world, won’t work in the end. If it seems to be working, then you haven’t fully understood at least one of them.

I leave you with a cartoon spotted on Digg recently:

I shall deal with gravity in three easy to swallow steps…

Step One: What is Gravity?

Gravity is the force felt by objects with mass, that pulls them toward other objects of mass. All mass in the universe is pulling on all other mass, all the time. You are attracting the computer screen, I am attracting the keyboard. Jupiter is pulling on your hair right now, as is the Andromeda galaxy and everyone in the room next door. Gravity is pervasive.

The strength of the pull of gravity between two masses (e.g. the mass of me and the mass of you) is determined by a famous equation, derived by Isaac Newton. In fact this equation is the subject of a t-shirt that is sold right here at Orbiting Frog.

F is the force of attraction, m(me) and m(you) are the two masses and r is the distance between the two masses. G is the gravitational constant and is a number that never changes. This kind of equation represents what is known as an inverse-square law. This refers to the fact that the force of gravity gets weaker as r gets larger by a factor of r x r. There are other inverse square laws in physics.

Step Two: How Does Gravity Work? - The Simple Answer

So having briefly covered what we’re taking about when it comes to gravity, we can now ask how gravity behaves and what is causing it. This was famously exemplified by Einstein with his General Theory of Relativity.

It is best to use an analogy here. Think of three dimensional space as a flat surface i.e. let’s ignore one dimension so our heads don’t explode. In this example we shall pretend that space is like a mattress, covering your bed.

If you put a big object on the mattress then other objects will tend to roll toward it if they get close enough. Try this yourself. Put a tennis ball on a bed and then go and put a heavy pile of books down on the bed next to it. The ball will roll toward the books, as if attracted by some force. By bending the fabric of the mattress you have created what looks like an attractive force between the two objects.

This is like the model that is used for gravity. The Sun is a very heavy object and it bends the fabric of spacetime around it, pulling objects toward it. Spacetime is the three dimensions of space plus time. You can think of it as the framework of the universe. Don’t get too carried away though, this is just a model. I don’t want you to think that spacetime actually is like a mattress! It just helps us to understand it better sometimes by making an analogy.

Step Three: How Does Gravity Work? - The Advanced Answer

So what is really happening? Why does spacetime seem like a mattress or a fabric on the face of things?

Quantum mechanics and something called the Standard Model are very good at modelling how the universe works. It tells us how three of the four forces of the universe operate. The electromagnetic force is conveyed via a particle called the photon. It is a massless piece of energy that moves through the electromagnetic field and thus transmits electromagnetic energy from one place to another. e.g. light travels from the Sun to your eyes via photons.

The strong force and the weak force are the two other forces covered by the standard model. Each of these also has a ‘carrier’ particle that transmits them across distances. These are atomic forces that only act on extremely small scales. They hold all your atoms together, so be grateful we figured them out or goodness knows what might happen!

Gravitons are postulated because of the great success of the standard model. In this framework, gravity is transmitted, or mediated, by gravitons, instead of being described in terms of our curved, mattress spacetime as above.

So why the two approaches? Well in on any large scale, the two models give the same result. The problem is that on a microscopic level, the massless graviton creates terrible mathematical issues that cannot yet be experimentally verified or corrected. Thus the graviton remains a theoretical particle… for now. Although people are looking for it.

If it exists then it fits in very neatly with the rest of physics and the graviton can start attending particle physics lunches without embarrassment. If it doesn’t fit in, then there is a problem. It would mean we have something wrong with our model and need to rethink quite a few things.

If you want to read more check out this Feynman book.

Link to Cosmic Variance post

Link to Quirks and Quarks Podcast