Many people think that weightlessness is a strange and even dangerous condition, but there's nothing particularly weird about it. Anyone can experience it (briefly!) by just jumping into the air, or for up to about a second by jumping off a wall. While you're airborne your body is in weightlessness. Trampolinists and high divers experience weightlessness for up to a few seconds.

Some people say "they feel their stomach jump", and that's quite right. Normally when standing up your stomach is pressing down on the organs below it (your guts), pulled down by gravity. But when you jump in the air, all parts of your body fall at the same speed, so your stomach no longer presses down on the parts below it. It "floats".

If you "stand on your head" your face goes red because blood which is normally trying to fall down into your feet when you're standing upright now tries to fall into your head. Being in zero G is in between the two - more like lying down. The fluids in your body are no longer trying to fall into your feet, and so people's faces tend to swell and become rounder than they are on Earth.

If you stay in zero G for months, your bones start to lose mass and get thinner, since they're not carrying weight. To counteract this you need to do particular exercises. But for a few days or weeks these effects are no problem. Also, in getting used to zero G your head learns to ignore what your inner ear is saying about your balance, so some people have some giddiness on their return to Earth (hence the chairs sometimes used by Russians returning from space; it's not because they're "basket-cases" as some newspapers have liked to suggest! Overall, a short stay in orbit has no ill effects.

If you're just visiting space in order to enjoy living in zero-G as most tourists will be, it's simply fun - as almost everyone testifies. For example:

• The first US woman to visit space, Sally Ride, said it was "the greatest fun of her life".

• After the repeated "parabolic flights" on board an aeroplane to produce 20-second periods of zero gravity while filming "Apollo 13", Tom Hanks said he never thought he'd have such fun again. (He will - once space tourism services start!)

• Shannon Lucid, after returning from spending 6 months on board the Russian space station Mir in 1996, said that if she had the opportunity she'd return to orbit on the next shuttle flight. "You just sort of get used to floating around." And remember - she was working busily in a cramped craft with one small window at the end of a tube - with a cover which was usually closed! Imagine how much more fun it will be when people are staying for pleasure and relaxation in hotel-like surroundings with picture-windows facing Earth!

Scientists prefer to use the word "micro-gravity" to weightlesness or zero G since, strictly speaking, the effect of gravity is only zero along the single line through the center of mass of an orbiting vehicle along its orbital path. Everywhere else in the vehicle there are "gravity gradient" forces tending to move things either "up" or "down" away from the center of mass. But these forces are very small. For you and I floating in an orbiting hotel, the effect of gravity gradients would be barely noticeable even in a room tens of meters across. (What would happen is that objects would drift very slowly "upwards" or "downwards" - away from the center of mass of the hotel.) In Space Future we use the terms zero G and weightlessness which are well-known and understood.

One of the big debates about orbital accommodation is whether more people will prefer zero gravity or partial gravity. Of the people who have spent time in orbit, there are those who prefer zero gravity, and those who think that partial gravity will be more popular. Of course no-one has yet created a partial gravity environment in orbit, because it's more complex to build a rotating station than a static one.

Some people take the view "What's the point of going to orbit - and then making artificial gravity? Just stay on Earth." Others say that partial gravity (for example 1/6 of Earth gravity - like on the Moon's surface) will be interesting compared to Earth gravity, but will be more convenient for living in than zero gravity, of which short periods for sports will be quite enough.

Like so many matters about space tourism, we don't need to predict. We can find out by experience. Companies will build both hotels providing zero G and hotels providing artificial G of different levels, and customers will decide which they prefer - just as they do with resort hotels on Earth. And the competition between different hotels will drive costs down, expand the market, and make it possible for more and more of us to make the trip.