Q & A

Do you think we are in any danger from a collision with an asteroid? maybe in my lifetime? i'm 23!

Aaron - Dortmund, Germany

Yes, I'm afraid I do! I cannot give you a probability, but the probability is definitely not zero. It's only recently that the governments of the world have been funding searches for possible disaster-producing asteroids. And some have come very close recently (even inside the orbit of the moon) BEFORE BEING DETECTED!. Clearly we need to work harder on detection, but even if we were to discover something of any size on a collision course with us, it is doubtful that we could with our present technology do anything to divert it. Sorry to be the bearer of bad news. There is no point in panicking though ... there are many other things which could severely limit our social lives which could happen tomorrow ... super volcanoes, for instance, or airborne plagues .... hmmm ... better make every day count ! Let's enjoy life!

cheers

Brian May

With reference to you 'Bullet Cluster' article on the Bang! website, how valid can MOND be as a way of defining the Universe without dark matter if it actually requires a particular form of dark matter for it to be consistent with observations of the Bullet cluster? Is this not just a case of this theory being a step towards defining what constitutes dark matter, thereby nullifying MOND theory itself?

Vernon Reeves

Hi Vernon,

MOND has always been successful in explaining observations of galaxies - particularly disk galaxies like the Milky Way - and it manages that without including any form of dark matter. It's only on the largest scales that the presence of other massive particles is required, and while this
doesn't change the validity of the theory, I certainly feel it removes a lot of the simplicity from the theory. The attraction of MOND has always been that by altering gravity we avoid the need for mysterious particles, and to find we need both is upsetting! That said, the KARIN experiment
will directly test for the kind of particles MOND predicts, so will soon know if they're correct or not.

Chris Lintott

We have received several questions asking about the availability of BANG! in Australasia.

General Question from BANG! readers

Further info for anyone asking whether/when copies are available in Australia and NZ: we have sold it to publishers in both.

Bookwise will publish it in Australia (out this month) and contactable on: www.bookwise.com.au and

Reed Publishing published it in New Zealand (it was published last Friday) and they are contactable on: www.reed.co.nz.

Carlton Books Ltd

Dear Dr. May,

Huge fan! Got that out of the way.

I am curious about your feelings regarding one very interesting question when it comes to the BIG BANG. Keep in mind as I ask this question that I do believe the Universe started with a concentrated explosion (if you will), and that it is ever-expanding as I type. However, no order ever comes from an explosion... only chaos and destruction. So, here is my question...

If the universe did in fact come from an explosive force, then how is it that so many recorded heavenly bodies have been found in "perfect" orbit around their gravitational centers?

I mean our little solar system in itself is a marvel, is it not? The precision it takes us humans to create a perfect satelite orbit around the Earth is painstakenly perfect, or it decays in either direction. Yet these 9 (old fashion statement any more) planets around our sun seen to maintain just that... a perfect orbit. How?

I welcome your thoughts and opinions here, and should you respond privately or on your website, I would let you know my theories on this matter.

Keep Rockin',

Eddie McCracken - CA, USA

This question and answer originated from the Brian May web site: www.brianmay.com

I think we have to clear up one thing here. The Big Bang, if it did indeed happen as we are suggesting in the book, is not an ordinary explosion. Explosions in our experience always burst out into a space which is already occupied, and of course this DOES cause disruption and destruction, to the objects which were there first. In the language of Physics, ENTROPY is increased, because more chaos, more disorder, is introduced.

But THE BIG ONE is entirely different. We believe the Universe was, and is, exploding into nothing .... we believe that Space and Time did not, and do not, exist outside that expanding fireball. So there coud be no-one standing outside to see it the way we have depicted it (for fun, really) on the cover of our book. And there would be no objects which would get disturbed. We are seeing here an EXPANSION - which perhaps actually has more in common with a balloon being blown up than Nov 5th Banger. So the question of why the Universe looks nice and neat in some ways does not arise. But even this is an illusion really. Your planets in 'perfect' orbits are in fact only stable for periods which are blinks of an eye relative to the grand scale of the Universe. As you'll see in the book, even our cosy, safe-feeling Earth is in a very unsafe place. At present it is an elliptical orbit at a comfortable distance from an apparently stable star, but this will not be so for long, cosmologically speaking. I'm afraid I don't see anything out there as 'perfect' - it is just what it is, a vast agglomeration of matter and energy churning around in a variety of ways, evolving, never still, never stable, and in fact always running down. Yes, Entropy will get the better of us all in the end!

Cheers

Brian May

Why can i feel the heat of the sun stood on Earth yet if i were to travel 50 million miles closer to it i would probably freeze at a molecular level, now given the trillions of stars in the universe that would produce an immeasurable heat source why does space remain absolute zero? by the way are there any plans to take BANG! on tour i.e book signings?

Paul Nicholson - Birmingham, UK

Hi Paul.

There are many facets to your question(s). I'm not sure if I can answer them all on this page .. but ....

To begin with, "temperature" is a concept that can mean different things in different situations - especially to physicists. In every-day life we think something is hot if it communicates heat to our skin .... but actually this can be for various reasons. In the height of a hot summer, you could pick up a leaf from the pavement and have no problem, but if you picked up a metal key from the same place, which would measure the same temperature, it would probably be too hot to hold. Similarly you could put your hand in some of the plasma in those pictures from Hubble, which is said by astronomers to be at millions of degrees K, and not feel a thing. Astronomers measure temperatures by the speed at which the molecules are rushing about and bumping into each other. If you did indeed go 50 million miles closer to the Sun, my feeling is you would not last long ... I don't know why you think you would freeze ... if you were suspended on space on your own, yes, the side of you which was facing away from the Sun would get pretty cold, but that is true for an astronaut even in the neighbourhood of the Earth. Luckily their suits give them protection. The big problem would be dealing with the direct heat of the Sun at that distance. You would be at about 43 million miles from our Mother Star ..... close to the orbit of Mercury. The surface of Mercury gets to over 400 degrees Centigrade, so it's a pretty safe bet that, unless you had an amazingly efficient heat-dispersing space suit, you would fry very quickly.

Your question about the temperature of space ? Very briefly, yes there are countless billions of stars in the Universe, emitting vast amounts of energy, but the stars are very far apart ... so far that if two galaxies collide, there are very few collisions between stars (this always suprises me! ) ... so all this radiation has an awful lot of space to fill ... the "Temperature of Space" is hard to define - you will get different answers by measuring different particles. As I understand it, a unique temperature can really only be assigned meaningfully to a volume which is enclosed and in equilibrium, so all the molecules have had time to share their energy with each other. I'm not sure who told you that Space is at absolute zero, but I can tell you that the laws of Thermodynamics do not allow this. There is no such thing as a perfect vacuum, and no particle can be said to be at absolute zero. This would actually conflict with the famous Uncertainty Principle too ... it would mean that we would know exactly where the particle in question was, and exactly how fast it was moving (not!). Heisenberg's great perception forbids this.

The last question is perhaps the hardest to answer. Book signings. These are just about the most scary events (to be in the middle of) known to Man. Of course I would like to sell loads of copies of BANG!, and get out there and meet our readers - but I am not sure if any of our bodies would withstand the stress! For now we are hoping that we will 'meet' many of our readers like this - ON LINE! Thanks for communicating.

Cheers!

Brian May

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