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

Given that astronomical observations do not need the horizontals but might serve to stabalise the structure - if it wasn't for the engineering needed to lift such monstrosities to that height. And alleged sacrifices were conducted at the altar, according to the conquering elite who tried to discredit the Druids. Is it not possible that dignitaries would given air burials in sacred places - after all the News Scientist published articles that stated there could have been air burials on borders of territories - eg Doggerland.

I want to know if my Dad had any last thoughts.....  Its been 2 years and I'm not going to be upset - I just need to know.  Thanks!

Why do thermal ink receipts fade out when you put them between statically charged surfaces?

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

My goal is to make my webpage (www.MyTree.TV) CO2-neutral! In order to reach this goal I intend to buy CO2-Certificates from www.newTree.org but the problem is that I don't know how to calculate the CO2-emissions of a webpage! The number of users is certainly important but if you consider just the electricity-consumption of a server it's not correct in my opinion. Does anyone know how to make a sound estimation?