The Experiment Seems To Confirm The Mind-Bewing Effect Of Penrose-Terrell, Predicted 66 Years Ago

The effect describes the strange way we see objects, such as a spacecraft moving at the speed of light.

The experiment visualized the prediction of objects moving at the speed of light, known as the Penrose-Terrell effect, first made more than 60 years ago.

When objects approach the speed of light (let's call it a spaceship, for convenience), several strange things happen. According to our best classical model of the universe, an observer looking at a passing spacecraft will see the length of the spacecraft shorter.

"Suppose the rocket flies past us at a speed of ninety percent of the speed of light," Professor Peter Schatschneider from TU Wien explained in his statement. "For us, it no longer has the same length as before take-off, but 2.3 times shorter."

Meanwhile, the spacecraft will perceive its own length as normal and see it as you, which has been shortened in length.

This, like the back of time, is a generally accepted part of Einstein's theory of special relativity. But other effects were predicted, including the obvious rotation of objects, passing away from each other at a relativistic speed. One of the predictions made by James Terrell and Roger Penrose in 1959 is that objects other than a sphere (with its enviable rotational symmetry) will seem rotated to another observer.

"It is shown that if the visible directions of objects are built in the form of points on the sphere surrounding the observer, the Lorentz transformation corresponds to the conformal transformation on the surface of this sphere. Thus, for a sufficiently small subject solid angle, the object will look - optically - the same shape for all observers. The sphere will be photographed with exactly the same round contour, whether motionless or moving in relation to the camera," Terrell explained in one of the 1959 articles on this topic. "An object with less symmetry than a sphere, for example, a measuring stick, will seem to be in rapid motion in relation to the observer, having undergone rotation, not contraction."

According to the works, this reduction and rotation cannot be photographed by the sphere.

"If you wanted to take a picture of a rocket when it flew past, you would have to take into account that the light from different points took different time to get to the camera," explained Shatschneider.

"At first, this result may seem paradoxical. For example, one might think that for a distant sphere moving perpendicular to the line connecting its center with the observer, smoothing in its direction of movement will certainly be obvious, Penrose and Terrell explained in another 1959 article.

"Since the tangents from the observer to the flattened sphere are almost the same length, it may seem that the final speed of light does not matter here. However, the light that seems to the observer to come from the leading part of the sphere leaves the sphere later, in the observer's frame, than the one that seems to come from the back. In fact, the light from the back reaches the observer because of the sphere, which he can do, since the sphere constantly goes out of its way. Thus, the length of the image of the sphere in the direction of movement is greater than one would expect, so if it were not for the flattening, the sphere would seem elongated."

While the spheres will look spherical, they will seem like a different pole, as if it were rotated. The effect is easier to explain with a cube, and it was with the help of the cube that the new team tried to visualize the phenomenon using extremely short laser pulses and a high-speed camera.

"We moved the cube and the sphere around the laboratory and used a high-speed camera to record laser flashes reflected from different points on these objects at different times," said Victoria Helm and Dominic Hornoff, two students who conducted the experiment. "If you specify the time correctly, you can create a situation that will give the same results as if the speed of light was no more than 2 meters per second [4.5 miles per hour]."

Imagine a hollow cubic structure moving at an absurd speed, or a slow version of this cube emitting incredibly slow waves of light. If two photons of light hit the eyes at the same time - one from the front of the cube and one from the back of the cube - this means that they were emitted at slightly different times, with the photon from the back of the cube emitted first.

"It makes us look like the cube has been turned," added Schatschneider.

"A train of laser pulses is sent to the object, and the reflected light is recorded with the help of a closed camera," the team specifies in its article. "The delay Δt between laser pulses and exposure is scanned, effectively revealing the movement of pulsed light on a static object. The trick of visualizing relativistic motion is to move the object to the distance it will move during the delay time Δt".

Using the setting, the team created a visualization of what we will see if the cube moves at a speed of 80 percent of the speed of light, and a sphere at a speed of 99.9 percent of the speed of light.

"We combined still images into short video clips of ultra-fast objects. The result was exactly as we expected," said Schatschneider. "The cube seems twisted, the sphere remains a sphere, but the North Pole is in a different place."