Field of bubbles
When I placed a glass of still mineral water in front of my computer screen I noticed that tiny bubbles started to form around the edge of the glass. Why does this happen and is the water still OK for me to drink? And if it was the screen that caused this, what is happening to my body, which is essentially liquid, when I sit in front of my computer?
鈥� The correspondent who claims that bubbles form in mineral water as a result of him placing a glass of water in front of a computer screen is mistaken about the cause.
I always have a glass of water by my side. If I leave that glass for an hour or two, without touching it or drinking from it, small bubbles form over the glass surface below the water level.
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I presume in your correspondent鈥檚 case that the mineral water was bottled from a pressurised source where more air was dissolved than would be if it was bottled at atmospheric pressure. In my case the bubbles come from the air dissolved due to the mains pressure in the pipes. The water is perfectly safe to drink, including its bubbles.
Gordon Thompson
Crewe, Cheshire, UK
鈥� Water has air dissolved in it and the colder it is the more air is dissolved. Fish tanks found in aquariums and homes make use of this dissolved air to allow the fish to breathe. They must also have some means of refreshing the air content of the water, or the fish will suffocate and die.
Your glass of mineral water was probably chilled when you poured it out so a lot of air will have been dissolved in it. As it warmed up, air came out of solution and formed bubbles on the side of the glass. Being in front of the monitor may have warmed the water a bit more quickly, but those bubbles were going to appear anyway.
Stephen Forbes
Leeds, UK
Spare parts
How many organs can be removed from the human body before it stops functioning well 鈥� in other words, without the assistance of medical devices? I know we can live with one kidney, half a brain, no gall bladder, no tonsils and no appendix. Any more?
鈥� There are quite a few more bits and pieces that you can do without. You can live with only one-third of a kidney and a third of your liver, provided these remain healthy. And, depending on how well they function, less than half of your lung capacity should be enough for you to continue to breathe successfully. One-tenth of your pancreas should supply you with enough insulin and you can part with your stomach, although that would cause some level of dyspepsia. A large portion of the small intestine and the whole of the large intestine and anus can go.
If you are an adult, you can say goodbye to your spleen without any dire consequences. You can live without your urinary bladder. Your limbs are not necessary, while teeth, tongue, eyes, nose, ears, breasts and many of your veins and some arteries can go too.
And if you don鈥檛 mind being reliant on drugs, you could do without your thyroid gland, the whole of your pancreas, adrenal glands and parathyroid glands.
Jan Strojil
Olomouc, Czech Republic
鈥� Assuming the end product of the removal of the various body parts is a person of relatively normal appearance while wearing clothes, and retaining the use of some limbs and senses, but allowing for medication, then our victim may lose toes, the large bowel and most of the small bowel, ending with an ileostomy (why bother to stop at the appendix?).
The person in question can also lose one kidney and the bladder with a urostomy. Waste water can still be passed. All the external and internal genitalia can be removed, as can the spleen, the pancreas, most of the liver and gall bladder, at least one lung and possibly a lobe from the other, the larynx with a tracheostomy, one eye, both external and one internal ear, teeth and hair.
We could niggle about how many fingers a person might need, but to lose a thumb is very disabling. And 鈥渉alf the brain鈥� is doubtful 鈥� people may develop with much of their brain missing, but to have a significant part of it removed always incurs some loss of function.
This person will need to use insulin, pancreatic enzymes, other diet supplements and antibiotics. With a greater reliance on disability aids, then it is quite possible to survive hemicorporectomy (amputation at the waist), amputation of the arms, and loss of the other eye and the internal ears. Obviously quality of life begins to become an issue at this point.
John Davies
Lancaster, UK
鈥� There is one body part that is positively beneficial if removed 鈥� the foreskin.
Guy Cox
University of Sydney, Australia
This week鈥檚 questions
Hello, I鈥檓 on the train鈥�
How fast must a train be travelling for the Doppler effect to put all the mobile phones being used on it out of action?
Philip Woodward
Malvern, Worcestershire, UK
Fly trap
A few years ago my attention was caught by a wasp apparently attacking the corpse of a freshly killed mouse. It dug quite a deep hole in the remains of the mouse and waited. A fly, failing to notice the wasp sitting in the cavity, landed on the corpse, climbed in the hole, and was promptly grabbed by the wasp. I watched as the wasp repeated this trick at least 15 times, carrying away each fly and returning a few minutes later to wait for a new visitor. Is this an example of tool use in insects, and has such intelligent behaviour been recorded before?
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