Hollywood loves to delight us with fantastic gadgets and amazing technologies, but it also has a tendency to go over the top. Remember the truly dreadful portrayal of tech in films such as The Net?

So how much of the sci-fi we see on our screens is actually possible - and if it's possible, how long is it before we can have it?

Let's find out the truth about our favourite on-screen inventions.

The Babel Fish

This one's organic rather than man-made, but it's still amazing technology: the only obvious drawback of Douglas Adams' Babel Fish is that you have to stick a fish in your ear (oh, and the theological arguments that resulted from the "bizarrely improbable coincidence that anything so mind-bogglingly useful could evolve purely by chance,") but the upsides are many: instantaneous, accurate translation of anything said to you in any language.

Is it movie bollocks? The fish bit is, obviously, but Google Translate is getting there: the latest version can translate handwriting as well as text.

KITT

Knight Rider's KITT (it's short for Knight Industries Two Thousand, which must have sounded amazingly futuristic back in 1982; in the 2008 movie the number was upped to three thousand) could see the road ahead, communicate with David Hasselhoff, play music and video and even let the driver play video games. KITT's memory capacity was a massive "1,000 megabits".

Is it movie bollocks? Not at all. Cars might not have KITT's, ahem, winning personality, but self-driving cars are mainstream now: many mainstream vehicles use crash-avoidance technology to compensate for driver error and, of course, Google is running fleets of autonomous vehicles.

Health pods

The health pods in Elysium aren't just magic cancer-killing machines that can rebuild your entire DNA. Oh no.

They're magic cancer-killing machines that can repair your head even if most of it's been shot off, right down to recreating the exact length of stubble you had before your meeting with Mister Shooty. And here's us thinking spray-on plasters are pretty clever.

Is it movie bollocks? Very much so, but while we can't magically rebuild people, we can use genetic scanning to identify potential problems before they occur, and nanomedicine to create very targeted drugs. For example, this week in India a nanomedicine for drug-resistant blood cancer was announced.

Glasses-free 3D

For us, our first sight of glasses-free 3D was in Star Wars with its holographic chess and communications. "When will we get such wonders?" we asked. "And will they be as horribly glitchy as that Princess Leia-gram?"

Is it movie bollocks? Nope. They may cost more than a Death Star, but glasses-free 3D UltraHD TVs have been around for a while now.

A remote control for reality

Wouldn't it be great if the same pause-live-TV tech we take for granted also worked in real life? That was the premise of Click, in which Adam Sandler used the real-life remote with the obligatory "hilarious results".

Our favourite bit was when he paused his boss mid-chat and walloped him repeatedly. We could do that all day. What do you mean, we have issues?

Is it movie bollocks? Yes. The closest we've got is the ability to delete our own tweets.

Time machines

From Back to the Future's time-travelling car to Looper's steampunk contraption, you'll find time machines of all shapes and sizes in sci-fi movies.

In many cases the travel is one-way, so you can travel backwards in time but not forwards, but that's not always the case. It's as if people are making this stuff up.

Is it movie bollocks? Probably. Where are all the tourists from the future?

Holodecks

Never mind virtual reality: Star Trek's holodeck offered simulated reality. Over to you, Wikipedia! "Objects and people are simulated by a combination of transported matter, replicated matter, tractor beams, and shaped force fields onto which holographic images are projected."

Is it movie bollocks? For now the Oculus Rift and the Igloo are as close as we've got. Virtual reality is much easier to do in your head than in an entire room.

Matter transporters

If you're optimistic you'll be thinking of the transporters from Star Trek, and if you're pessimistic you'll be remembering what happened in The Fly.

Matter transportation solves the problem of travelling large distances by scanning your individual atoms, disassembling you, and then rebuilding you somewhere else - with not only your body but your consciousness intact.

Is it movie bollocks? Not necessarily. Scientists have used quantum teleportation to transmit data over 89 miles, although doing the same with people is a very long way off - assuming that it's even possible.

Active camouflage

Where human soldiers use traditional forms of camouflage, the titular Predator had a much better system back in the 1980s: its active camouflage changed as the monster moved, rendering it almost entirely invisible.

Is it movie bollocks? No. BAE has been working on active camouflage for tanks that uses sheets of metallic pixels and on-board cameras to make vehicles disappear, although similar tech for soldiers isn't remotely cost-effective yet.

Brain erasers

Men In Black used them on passers-by and the characters in Eternal Sunshine of the Spotless Mind used them to forget unhappy memories, but the idea was the same: machines that could selectively erase your memory, enabling you to forget a very specific memory or selection of memories without also forgetting who you were or how to walk.

Is it movie bollocks? Not necessarily. Researchers in Florida have found ways to delete memories from the brains of rodents by blocking proteins.