HUMAN LIMITATIONS
1. Human Speed: Last year, Usain Bolt stunned athletics fans when he hacked 0.11 seconds off his previous world record for the 100-metre sprint. But what's the ultimate human speed limit?
2. Concentration: It's a challenge that most of us have faced when up against an essay deadline, a late-night crisis in the office or perhaps a long car drive. Just how long can we push ourselves mentally before our brain needs a break?
3. Survival in a Vacuum: Sadly we know how long humans can survive if suddenly exposed to the vacuum of space. Three Soviet cosmonauts died in 1971 when a faulty valve caused their Soyuz 11 capsule to depressurise at an altitude of 168 kilometres, shortly before re-entry into the Earth's atmosphere. Investigations revealed that the cabin pressure dropped to zero for 11 minutes and 40 seconds, until the capsule hit the atmosphere. The crew died within 30 to 40 seconds from hypoxia. "You need both oxygen and air pressure to deliver oxygen to the brain," says Jonathan Clark, a former space shuttle crew surgeon.
4.How Much Can We Remember: Remembering an 11-digit telephone number is hard enough for most of us. Yet one of the current record-holders for a feat of memory, Chao Lu of China, was able to accurately recite 67,890 digits of pi from memory in 2005. But is that a mere drop in the ocean compared to the brain's true capacity?
5.Holding Your Breath: Most people find it hard to hold their breath for more than a minute, so imagine the extreme self-control Stephane Mifsud mustered on 8 June last year when he held his breath for 11 minutes and 35 seconds, setting a new world record for stationary breath-holding, or "static apnoea".
