The video above compiles some of the most striking videos captured by an MRI machine, including a quasi-NSFW clip of a couple having sex. Magnetic Resonance Imaging has been commercially available since the 1980s, but more recent improvements in resolution and computing have made it possible to build videos from the scans, and even provide technicians with detailed real-time moving images.
MRI scanners generate an image of the human body by mapping the position of hydrogen protons, which are abundant in the water molecules and the fat in our tissues. The machines create a strong magnetic field so that when the patient is placed inside it, the hydrogen protons in their body align like a needle in compass.
By sending pulses of energy via a specific frequency of radio waves into the body, the MRI machine alters the behavior and orientation of the protons momentarily. When that radio signal is shut off, the hydrogen protons realign with the magnetic field and in doing so, emit radio waves that communicate their position in the body and the type of tissue in which the reside. Pretty brilliant, right?
What it's like to make love in an MRI machine
In 1999 Dutch scientist Pek van Andel created the following video of a couple having sex inside an MRI machine, as part of a study on the feasibility of recording images of a couple having sex inside an MRI machine (hypothesis confirmed):
Ida Sabelis, an anthropologist and one of the subjects of the study, said this about her experience (through an amateur translator, apparently):
Suddenly I become conscious that I have a strange position: the only woman between four men, on the verge of becoming intimate with my lover in that machine, while the other three gentlemen in the next room are operating all sorts of machinery to take a shot of our inner side. [...]
Then nothing for a little while. Confined by the space we make the best of it and that’s just not so uncosy. On a certain moment there’s sounding through the microphone "the erection is fully visible, including the root." Again nothing for a little while. ... The first shots are taken: "Now lay down very still and holding your breath during the shot.!" Forty rythmic little bangs of the magnets above us and then one may exhale. [...]
It's becoming pleasantly warm in the tube and we truly succeed in enjoying each other from time to time in a familiar way. When the microphone is telling us that we may come- insofar possible- and that only we have to inform them in connection to the photo, we burst out into a roar of laughter and some moments later we do what is the purpose.
Birth, as seen by magnets
Radio waves are harmless — unlike X-Rays and CT scans, which rely on high-frequency, ionizing radiation that can damage cells. MRI scanners are noisy though (in some cases as loud as a rock concert) because the metal coils of the magnet vibrate when the electric current is switched on and off. That's why the video of live birth cuts off when the baby's head emerges — they didn't want the noise to damage the baby's hearing:
The video has many more examples, including a beating heart and a person drinking pineapple juice. It's a fascinating way to look at the body from the inside.