Using ultra-fast laser pulses and special cameras, scientists have simulated an optical illusion that seems to defy Einstein's theory. special theory of relativity.
One consequence of special relativity is that fast-moving objects should appear to be shortened in the direction of their motion, a phenomenon known as Lorentz contraction. This effect was indirectly confirmed in experiments at particle accelerators.
Although previous models have worked with this illusion, now called the Terrell-Penrose effect, this is the first time it has been done in a laboratory setting. The team described their results in a journal Physics of communication.
“What I like most is simplicity” Dominic Hornoffquantum physicist at the Vienna University of Technology and first author of the study, told Live Science. “With the right idea, you can recreate relativistic effects in a small laboratory. This shows that even centuries-old predictions can be brought to life in a truly intuitive way.”
Recreating the Illusion
In the new study, physicists used ultra-fast laser pulses and gated cameras to create images of a cube and sphere “moving” at almost the speed of light. The results showed images of rotated objects. This proved the validity of the Terrell-Penrose effect.
But like every study, this one also had its challenges. Moving any object at or near the speed of light is currently prohibited. impossible. “In Einstein's theory, the faster something moves, the more its effective mass increases. As you get closer to the speed of light, the energy you need increases significantly,” Hornoff said. We can't generate enough energy to accelerate something like a cube, and that's why we need huge particle accelerators, even just to move electrons close to that speed. This will require a huge amount of energy.”
Therefore, the team used a cunning replacement. “What we can do is simulate the visual effect,” Hornof said. They started with a cube about 3 feet (1 meter) on each side. They then fired ultra-short laser pulses at the object—each lasting just 300 picoseconds, or about a tenth of a billionth of a second. They captured the reflected light using a closed camera, which was opened only for that moment and took a thin “slice” each time.
After each cut, they moved the cube forward about 1.9 inches (4.8 cm). This is the distance it would travel if it were traveling at 80% the speed of light during the delay between pulses. The scientists then combined all these fragments into a snapshot of a moving cube.
“When you put all the pieces together, the object looks like it's moving incredibly fast, even though it never moved at all,” Hornof said. “At the end of the day, it's just geometry.”
They repeated the process with the sphere, moving it 2.4 inches (6 cm) per step to simulate the speed of light at 99.9%. When the slices were combined, the cube appeared to be rotated and the sphere looked as if one could see beyond its sides.
“Rotation is not physical,” Hornoff said. “It's an optical illusion. The geometry of how the light hits at the same time tricks our eyes.”
This is why the Terrell-Penrose effect does not contradict Einstein's special theory of relativity. A fast-moving object is physically shortened in the direction of its movement, but the camera does not record this directly. Because the light from behind takes longer than the light from the front, the shot is shifted so that the subject appears rotated.
“When we did the calculations, we were surprised how well the geometry worked,” Hornof said. “Seeing it appear in the images was really interesting.”