This week's watchword has to be "random". We've had the kind of thought-provoking, fun questions that make The Last Word such an interesting forum, ranging from ornithology to mathematical philosophy.

Starting off with physics, have you ever wondered how fast bubbles rise? ln64z3 asked us: what is the speed of bubbles? And while we still don't have a definitive velocity, we do have suggestions of how to find one out http://bit.ly/fgy2tq?.

Onto a bit of arithmetic: 2 + 2 = 4. Or does it always? See what the Last Worders made of this seemingly cut-and-dried question http://bit.ly/e7NFWS?, which also went down a storm on Facebook http://on.fb.me/eij6MP.

Getting a bit more biological, possibly inspired by seasonal migration, petefinn asks why, if flying in a V formation is meant to allow them to maintain visual contact, why do ducks quack during flight? http://bit.ly/esFESm. Heading over into human physiology, benpbway asked us: how sweaty do you get in the bath? http://bit.ly/eljK7Y We're still looking for that answer – can you supply it?

Finally, we finish with something on my Christmas wish list – a Harry Potter-style invisibility cloak. Is there any chance of such a thing existing? http://bit.ly/h4s8Iz? If you know how to make one, send a prototype my way!

Wishing you a smashing weekend,

Kat

Letters and comments editor, New Scientist

Image:  phil landowski/stock.xchng

We have had a week of involved debates on The Last Word. markct1989 caused a storm with his question: how do you define temperature? Check out the various definitions suggested by the Last Worders: http://bit.ly/dYJwIi

Another debate, which has been raging for over a week, stems from translatrix's observations that the amount of water in a sealed plastic bottle seems to decrease over time. Can water evaporate through plastic? http://bit.ly/g2SOWv

petethebloke asked us: how long have humans been as intelligent as they are now http://bit.ly/exZyaD? The question got our Facebook followers ever so excited: http://on.fb.me/dL0IK0

Another of this week's questions was similarly popular on Facebook: why do flames make a noise when you blow them out? See if you think Last Worders http://bit.ly/dWU3me? or Facebookers http://on.fb.me/h9Dzfh have got to the bottom of it.

Our very own Feedback editor joined the fray this week when tbrucenyc wanted a bit more explanation of one of the week's Feedback items. What's so funny about computer algorithms? Find out here: http://bit.ly/gN5KyS

If you want to test your mettle, why not see whether you can provide an explanation as to why fingernails grow faster than toenails? http://bit.ly/hohXCg

Hope you have a great weekend,

Kat

Letters and comments editor, New Scientist

Image: www.shutterstock.com

Welcome to another round-up of the week's excitement on The Last Word, and what a collection of questions and answers I have for you this week!

Ever been out camping and found you've forgotten to bring matches? In the daytime you can always whip out a mirror and use sunlight to spark your fire… but can you light a fire with starlight? The Last Worders have a crack at quantifying the likelihood here: http://bit.ly/dMB0Fc. That's not the only option though, you could employ the method that caused a spontaneous fire in Paul_Pedant's briefcase: http://bit.ly/fpzgV7

Suppose you desperately need to cook a turkey and you still can't light a fire. Well, maybe there's a more unconventional solution. This week, doedfisk asked us: what's the optimum altitude from which to drop a turkey so that it cooks on re-entry to the Earth's atmosphere? http://bit.ly/emIFmC

Now for something a little different. How do you relate bones to Greek legends? Last week Apqad asked us whether, if you didn't know what an elephant looked like, you could tell from looking at its skeleton that it had a trunk and large ears. LokiNight has just come up with a very interesting answer relating prehistoric dwarf elephant skulls to the Cyclops legend of ancient Greece. You can find out more here: http://bit.ly/dTnVTz

Keeping on the theme of bones, is cracking your knuckles bad? http://bit.ly/h6rG3z? In my opinion, yes, if I have to hear it. I get grossed out by my own ankle clicking.

To finish off we have something completely different. John Chapman asks: how do anti-static sprays work? Where do the electrons go to or come from to neutralise a charged surface? http://bit.ly/glpe6h

Just to remind you, if you answer any of the questions that appeared in New Scientist magazine – like John Chapman's question above – and we print your answer on The Last Word page of the magazine, you will win a cheque for £25 (or the US$ equivalent). But we can only send it to you if you provide us with your address in your online profile!

Have a great weekend,

Kat

Letters and comments editor, New Scientist

Hello Last Word folks, are you looking forward to the weekend?

If you are going to watch some kind of sports this weekend – say the Aston Villa v Arsenal match tomorrow that is likely to split my family down the middle – why not spend half-time pondering how many goals would be scored if you played football with two balls? http://bit.ly/etUcCq?

Or perhaps you'll be seeing the in-laws? In which case this question might be more pertinent: why is it that so many people can't keep their noses out of other people's lives? http://bit.ly/eeqhjf Do you think there could be an evolutionary advantage to interfering?

Last weekend saw some animal experimentation, in the form of gummy bear-icide by Last Worder ln64z3. On trying to melt one of these cute candies over a campfire, he was most surprised to see it bubble instead of melt. Can you help explain why it frothed instead of dripping as you might expect? http://bit.ly/9dqkn2?

While ln64z3 was having fun toasting gummy bears, I was flying back from a diving trip in Egypt. So I was thrilled to see a timely question on The Last Word to greet my return. dendurrant has been wondering why the Red Sea is so much warmer at depth than other seas and oceans. It seems I have the thermal vents in the seabed to thank for keeping me warm: http://bit.ly/gPiDaA

Finally, here is a question still in need of a complete answer. Can you tell us why some hairs are thicker than others? We have had some amusing and informative answers, but are still in need of an expert to solve the query: http://bit.ly/i8BM8r?

Hope you have a fantastic weekend,

Kat

Letters and comments editor, New Scientist

Another week, and another rash of great questions on the Last Word site. We started on a fishy note, with baloo asking why it is that fish gills only work in water. Find out why here: http://bit.ly/b4w8n5

canivet290468's question caught my eye, as my morning train ride in to the New Scientist offices has been shrouded in mist most of the week. If you could assemble a temporary building in seconds in thick fog, would you still see the fog inside?? http://bit.ly/aCW5UE

Fitness fanatics among you might be intrigued by mal14's poser: when you burn fat off, where does it actually go? Well, where does it go? Down the toilet or somewhere else? http://bit.ly/92qVQh?

The penultimate question is particularly poignant for me, as I sit typing before I head out of the office for lunch. draki asked why some people get irritable when they're hungry? http://bit.ly/dwS8u9? I'll do my best to behave calmly, dear reader, but I am in need of food.

So let's quickly finish up. Here's a final question to get you thinking over the weekend. What is technology doing to the evolution of the human species? Have your say here: http://bit.ly/9N42z4

Have a great weekend, and make sure to eat enough to stave off bad moods.

Cheerio,

Jamie

Are you sitting comfortably? I am, I'm sitting with my legs crossed. Of the four people whose legs I can see from my vantage point in the New Scientist offices, three others are sitting the same way. So why is it that we instinctively sit with our legs crossed? http://bit.ly/9aJ7HK?

There have been some planetary ponderings this week on The Last Word. hugolabs wondered if we can determine the thermodynamic state of a planet. What do you think – can we calculate whether a planet emits more heat than it absorbs? Have your say here http://bit.ly/bU2hHM and check out what our Facebook group thought here http://on.fb.me/cTxX9l

Similarly, alanrbarrowXqzBk wondered if the mass of the Earth varies. With meteorites crashing into the planet, and the dynamic between gaseous, liquid and solid material, is the mass of the Earth increasing? http://bit.ly/baDmSn

If all that space-based fun gets you hot under the collar, maybe you'll be interested in Marmaduke's question. He asked The Last Word, given that humans evolved to live in hot environments, why is it that we all prefer air conditioning to being stuck in the heat? http://bit.ly/9fAQRl

Finally, here's something for the weekend: it might come in handy if you have occasion to prepare a Sunday roast. Why is it that when frozen peas are put into a pan of water some float and some sink? http://bit.ly/c9VkBo

That's all from me for this week! Have a great weekend.

Peas!

Kat

Letters and comments editor, New Scientist

We've had great, and complicated, group of questions this week on The Last Word. Starting small, jagged asked if birds rehearse their songs. So far, the answers seem to suggest they do, but you can have your say at http://bit.ly/aIm8ap?.

That wasn't the only animal-based question. philthepower1985 asked Last Worders to identify a creature he's stumbled across. Nobody seems to know at the moment – you can make your suggestions here http://bit.ly/bRoMJt?.

translatrix has been pondering whether we have the technology to produce glasses that could help us distinguish colours more easily. We're not sure if it would be a good idea to look at The Last Word website wearing them, but you can read what people have to say about it here http://bit.ly/cy2Fh4?.

My personal favourite this week was asked by johnconnellx, who asked: what is the pH of the universe? This has got discussion going, especially as pH can only be measured for aqueous solutions. Here at New Scientist we're neutral on the subject, but you can join in the debate here http://bit.ly/cu4FHs.

Our final question of the week comes from our very own KatLastWordHost. Because the UK's sky will be filled with fireworks this evening to celebrate Bonfire Night, she wonders how much damage a stray firework could do to a passenger plane fuselage? Let her know here http://bit.ly/9jzcs3.

Have a great weekend, and enjoy the fireworks if you're in the UK.

Cheerio,

Jamie

We had a host of interesting physiological questions this week on The Last Word, not least was Jen.elise's "Can you breathe through your ears?" http://bit.ly/bq7AaJ?. After some wrangling over the various possibilities, the general consensus was that it would perhaps be possible but painful. An intriguing offshoot to the discussion was tbrucenyc's suggestion that you can hear through your open mouth.

danredfern has been wondering how giraffes regulate the blood flow to their brain when bending their head to the ground. He calculated that the pressure in the arteries generated by the movement would be very high – in fact, double the pressure that would cause a haemorrhage in humans. So why don't giraffes keel over when they bend their necks? http://bit.ly/b7bZE2.

With the budget cuts in NASA's space programme, the sci-fi dream of living on Mars might seem a long way off. That hasn't stopped Last Worder Milon from thinking ahead: he's been wondering how fast we will be able to walk when we get there. Not only that, when we set up a colony and settle in (getting very hopeful there, Milon), will human beings adapt and end up walking at the same speed as they do here on Earth, or will we walk faster or slower because of the difference in gravity http://bit.ly/axxeCI?

Coming back down on Earth with a bump, Cliffo wonders why there are no devices on aircraft to spin the wheels in order to stop the rubber burning up on touchdown http://bit.ly/clmVfp.

Ever wondered how to make a flame-thrower? drdingus did, and generated a lot of suggestions from the forum – almost all of which were prefixed with "Well, if you want to get yourself killed…" Indeed, interesting reading but definitely don't try this at home! http://bit.ly/ah6cwD

Wishing you an inventive but flame-thrower-less weekend,

Kat

Letters and comments editor, New Scientist

This week we've had three questions exploring the human body. john.dalgleish wondered why hard work and exercise causes physical development. Here at New Scientist we don't get to leave our desks too much, so it's up to you to suggest your own ideas at http://bit.ly/c7Jikn.

Alan Williams made us squirm when he asked why pulling out nasal hairs makes our eyes water with pain. Last Worders have suggested that there's a high concentration of nerve endings in the nose, and that the eyes and nose are also linked by the same facial nerve. Personally, I agree with petethebloke: maybe Alan should try trimming instead of plucking. Have your say at http://bit.ly/dvWs8b.

The final question about the human body came from Philip2511, who wondered why he shivers when he yawns. If you've got any ideas, let him know here: http://bit.ly/9QrA3E?.

Changing topic altogether, KaterinaChristoforou asked if plants ever die suddenly like humans? This one sparked great debate amongst Last Worders, especially over quite what counts as death. To read more, or have your say on the matter, head to http://bit.ly/aXoqDC.

And finally, one to keep you amused over this cold, autumnal weekend (for those of us in the northern hemisphere, anyway): what is fire made of? http://bit.ly/aBznxI

Have a great weekend, and keep warm!

Cheerio,

Jamie

This week we had two questions on colour. marcparry wondered why his left eye sees colours more vibrantly than his right. The Last Worders provided a variety of explanations – decide which you think is right or add your own at http://bit.ly/cgHgdb?. The debate continued on Facebook, with Marc himself getting involved there as well http://on.fb.me/cAUFDv. How multimedia!

Our second colour-related question regards the spice saffron. In its raw form it is red, so why do the foods that it is added to – rice or soup, for instance – turn yellow? http://bit.ly/aIsTk4

My personal favourite question came from Friedag, who noticed that plastic boxes in his basement became fused together if left for a long time. Is there a chemical process involved? If not, what is happening? There may not yet be a conclusive answer, but there is some rather diverting discussion to be found at http://bit.ly/bH0s1G?

How many sheets of paper would it take to stop a bullet? As Paul_Pedant blithely commented, if you listen to war stories the sheets are much more effective when formed into a Bible. More lively scientific exchange followed at http://bit.ly/d9BbGl?

And here's one for the weekend: why is it when you stay in bed for longer you feel more tired? http://bit.ly/bGAzz2

Hope your weekend is restful – but maybe not too restful.

All the best,

Kat

Kat Austen, letters and comments editor, New Scientist