This photo shows a green sweet that has been discovered by ants on a paved path in my garden. The sweet had been dropped several hours before, and had attracted the interest of an ant colony which was carrying it away. But the pattern of the surrounding plant debris is a mystery. What accounts for its arrangement around the candy?

Roy Levian, Lexington, Massachusetts, US

When I buy asparagus and keep it too long small beads of liquid appear on the tips. Why does it seem to decay preferentially from the tips, and what is the composition of the liquid that appears there? More importantly, can I still eat the asparagus after the liquid starts to appear?

Tyler Keaton, Bolton, Lancashire, UK

My daughter has an old victorian brass microscope mounted in a mahogany case. Most of the time this sits in my study and is only brought out to look at on occasions. New Year's Eve turned out to be one such occassion, when some of our party, rather full of seasonal spirit, decided to investigate some of out antique scientific instruments. The last time my daughter had put the microscope away, she had stuffed a polyethylene supermarket bag into the box, to hold the package of slides in place - that was probably a couple of years ago. And something bizarre had happened: the bag had become extremely brittle, locked into its scrunced-up shape, It had also become extremely fragile, dissolving into tiny flakes when touched, and even smaller flakes/powder when a handful of flakes were rubbed together. The flakes and powder had a very strong 'brassy' smell. The bag was least friable in the centre of the scrucnched-up 'ball', but even there it fell into the same flakes with a slightly heavier touch

What has caused this? Googling to find out what reaction might be happening, I couldn't find anything, but mentions of brass fittings on polyethylene pipes failing came up, which could be related?

More information: The bag was definitely not a biodegradable bag, I've checked that. I'll see if I can find out more about it.

The last time the microscope was cleaned will have been at least 25 years ago and then it would probably have been with duraglit wadding... but I'm not sure whether it was ever cleaned like that. Most of the time it sits in a closed mahohany box.

So: no sunlight, it would have been completely dark in the box, which is stored in a corner of my study. Ambiant temperatures would have ranged between about freezing point and about 27 degreex C in summer, I suppose. No solvents I can think of, and as I said, a very strong 'brassy' smell to the degraded plastic. I am experimenting with another bag in a screw-top brass jar which I know has only ever contained water, and that 100 years ago!

I heard the question 'what happens when an Unstoppable force hits an immoveable object?' and I thought that the force would just go through the object, is this possible?

Why does the Roayal Mint only issue the current years coinage in December?

I've always noticed that the current year's coins only appear in circualtion at the end of the year - I'm sure the 2010 coins will popup soon, I've not actually seen any yet.

Why is this - is the mint stockpiling for the whole year before releasing them to the general public?

Cheers

fj

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

Mathematically, this is sum of zeros. All definitions of a line are that it has no “width” but should it also be true that it should ahs no “length”?

Is this true?

Most people know about 3Ds. And some people have theories on 4Ds. So my question is, how many theories on new dimensions(if there is any) have been created? What are these new dimensions called? And have these theories ever been acknowledged by other people?