How many times will your heart beat?

Each Thursday morning, between 3am and 4am UK time, Dr Karl answers any science questions whatsoever that Radio 5 listeners can throw at him. This week, he was joined by Dr Chris Smith. It's brilliant stuff. For example, you know the feeling that one nostril is partially blocked whilst the other is free? Well, apparently this is by design: larger molecules take longer to lock into the nerve cell receptors in the nose, and these require reduced airflow. Other smaller molecules lock into place quickly, and these can be smelt via the larger airflow in the other nostril. (If the BBC Radio Player doesn't work via this link, go to the Up all Night page, look for Thursday, and click on 'Listen' next to 'Dr Karl answers your science questions').