Hello you know those movies about zombies and that they die if you shoot them in the head they die and if the bite you turn into them, while is was watching day of the dead (new movie) i was thinking what if they acctually come to life well you never know.So what i want to know is if zombies could acctually come to life? thank you newscientist i love your new book Do polar Bears ever get lonely and 101 questions.

This answer has been selected and edited by New Scientist staffSeeing the curvature of the Earth can mean either seeing the surface of the Earth in front of you fall away towards the horizon, in the same way that you see the ground fall away when standing on a rounded mountain top, or seeing the horizon as a curved rather than horizontal line.It is actually possible to see the curvature of the Earth, in the second sense outlined above, at any height: for example, sitting on the beach, standing on the deck of a ship or looking out of a plane window. This is to be expected, because a view from any point on a sphere such as the Earth will give the horizon as a disc. The height of the viewpoint will simply determine its size.The visual cues employed to see the curvature of the Earth are many, but judging the line of the horizon relative to the horizontal is generally not one of them. Instead, two more obvious cues are noting that the distance of the horizon is the same in any direction, and seeing that the texture gradient - the way a view changes in appearance and perspective with distance - of the sea or land is constant within that distance.I agree that increased viewpoint height will yield a richer set of cues, especially those associated with seeing the horizon in the second sense, delivering a more obvious curvature. Nonetheless, this curvature can still be noted at sea level.John Campion, Psychologist and vision scientist, Liphook, Hampshire, UK

Re - curvature of the EarthDriving from Riviére du Loup to Quebec City there's a good stretch where the St. Lawrence river is about 12 (= 2 x 6) miles wide and you are down almost at water level. On a good day it's very obvious that the centre of the river obscures both the opposite bank and the lower parts of houses lining it. Maybe there's some effect from flow, but almost certainly a good part of it is the river's surface curvature over the Earth.The traffic's easy, so one day - assuming the river was obscuring about 15ft of the other side, and using the "intersecting chords" theorem - I calculated the Earth's diameter to be about 12,600 miles.Well, this was a bit high, but it could easily be just over 20ft that is obscured, which would give a figure close to the proper diameter.Tony SharpeAlmonte, Ontario, Canada

I have often noted the curvature of the Earth from the summit of Orcas Island in Washington state. It's not the horizon that looks curved, but the surface of the Earth itself. I wouldn't see the curvature if I weren't so familiar with nautical charts of the area. The ratio of the altitude of Orcas above sea-level, and the height of my eye above the table where I spread out my maps seems to be roughly equal. The map's scale plays a part as well. The 'curvature effect' is striking.

This answer has been selected and edited by New Scientist staffEvery time I read yet another theoretical contribution to your debate over whether the curvature of the Earth is apparent from the top of Blackpool Tower, I turn to the front cover of the magazine just to check that the word "scientist" is really still there.I would have thought that by now someone would have followed the scientific method: just do the experiment and report the result. I would certainly have had a look if I lived a little closer.John Twin, Ross-on-Wye, Herefordshire, UK