Physicists in Vienna have recreated a bizarre visual illusion from Einstein’s relativity—the Terrell-Penrose effect—by simulating slow light speeds with lasers and cameras.
A fast-moving cube appears twisted, as predicted over 60 years ago.
Relativity Gets Weird at Light-Speed
When things move really, really fast, close to the speed of light, our everyday ideas about space and time start to break down. This is the heart of Einstein’s special theory of relativity. Objects actually shrink in length as they speed up, and time flows differently for them than it does for someone watching from the outside. Sounds wild, but it’s been confirmed by countless experiments.
But there’s one mind-bending prediction of relativity that had never been seen, until now. It’s called the Terrell-Penrose effect, and it says that super-fast objects shouldn’t just look shorter, they should look rotated. Back in 1959, physicists James Terrell and Roger Penrose came to this conclusion independently. And now, for the very first time, scientists in Vienna have managed to visually recreate this strange illusion using high-speed cameras and laser pulses, by slowing down light itself to just 2 meters per second in a clever lab setup.
The Faster You Go, the Shorter You Look
“Suppose a rocket whizzes past us at ninety per cent of the speed of light. For us, it no longer has the same length as before it took off, but is 2.3 times shorter,” explains Prof. Peter Schattschneider from TU Wien. This is the relativistic length contraction, also known as the Lorentz contraction.
However, this contraction cannot be photographed. “If you wanted to take a picture of the rocket as it flew past, you would have to take into account that the light from different points took different lengths of time to reach the camera,” explains Peter Schattschneider. The light coming from different parts of the object and arriving at the lens or our eye at the same time was not emitted at the same time – and this results in complicated optical effects.
Relativity’s Illusion: A Rotated Cube
Let’s imagine that the super-fast object is a cube. Then the side facing away from us is further away than the side facing towards us. If two photons reach our eye at the same time, one from the front corner of the cube and one from the back corner, the photon from the back corner has traveled further. So it must have been emitted at an earlier time. And at that time, the cube was not at the same position as when the light was emitted from the front corner.
“This makes it look to us as if the cube had been rotated,” says Peter Schattschneider. This is a combination of relativistic length contraction and the different travel times of light from different points. Together, this leads to an apparent rotation, as predicted by Terrell and Penrose.
Of course, this is irrelevant in everyday life, even when photographing an extremely fast car. Even the fastest Formula One car will only move a tiny fraction of the distance in the time difference between the light emitted by the side of the car facing away from us and the side facing towards us. But with a rocket traveling close to the speed of light, this effect would be clearly visible.
Recreating Relativity in a Lab
Technically, it is currently impossible to accelerate rockets to a speed at which this effect could be seen in a photograph. However, the group led by Peter Schattschneider from USTEM at TU Wien found another solution inspired by art: they used extremely short laser pulses and a high-speed camera to recreate the effect in the laboratory.
“We moved a cube and a sphere around the lab and used the high-speed camera to record the laser flashes reflected from different points on these objects at different times,” explained Victoria Helm and Dominik Hornof, the two students who carried out the experiment. “If you get the timing right, you can create a situation that produces the same results as if the speed of light were no more than 2 meters per second.”
Snapshots Across Time Reveal the Impossible
It is easy to combine images of different parts of a landscape into one large image. What has been done here for the first time is to include the time factor: the object is photographed at many different times. Then the areas illuminated by the laser flash at the moment when the light would have been emitted from that point if the speed of light was only 2 m/s are combined into one still image. This makes the Terrell-Penrose effect visible.
“We combined the still images into short video clips of the ultra-fast objects. The result was exactly what we expected,” says Peter Schattschneider. “A cube appears twisted, a sphere remains a sphere, but the North Pole is in a different place.”
When Physics and Art Collaborate
The demonstration of the Terrell-Penrose effect is not only a scientific success – it is also the result of an extraordinary symbiosis between art and science. The starting point was an art-science project by the artist Enar de Dios Rodriguez, who several years ago, in collaboration with the University of Vienna and the Vienna University of Technology, explored the possibilities of ultra-fast photography and the resulting ‘slowness of light’.
The results have now been published in the journal Communications Physics – a step that may help us understand the intuitively elusive world of relativity a little better.
Reference: “A snapshot of relativistic motion: visualizing the Terrell-Penrose effect” by Dominik Hornof, Victoria Helm, Enar de Dios Rodriguez, Thomas Juffmann, Philipp Haslinger and Peter Schattschneider, 1 June 2025, Communications Physics.
DOI: 10.1038/s42005-025-02003-6
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10 Comments
Physicists in Vienna have recreated a bizarre visual illusion from Einstein’s relativity—the Terrell-Penrose effect—by simulating slow light speeds with lasers and cameras.
VREY GOOD.
According to the topological vortex theory (TVT), the human visual illusion must always be viewed in two parts. The Uncertainty Principle truly reflects the essence of spatiotemporal motion in the material world. Scientific research guided by correct theories can enable researchers to think more.
First, this is an artifact of math – which contracts linear numbers. What most people don’t think about is that it contracts every number. It’s a bit of a mind virus, so we’re lucky it doesn’t escape a given use or it might infect all numbers – where you wouldn’t even be able to count on a cup of flour reliably. :-}
It did give the obvious idea that curvature can be introduced to straight lines – and therefore direction in space, hence curved space. Lucky for him, the ‘space’ we think of is curved.
But don’t worry, you don’t have to think more on that.
Physics question: What about a person inside the rocket? Is their size affected, too, by the the same ratio? What happens to their perception of things–even if this is merely a hypothetical, or as suggested, an artifact of math?
English Language Use: The English word to describe physical distance is “Farther.” Further used is for all other purposes of conceptual, non-physical distance, such as, “As we look further into this…” Sometimes further is akin to saying, “additionally.”
The sentence should be: “Then the side facing away from us is farther away than the side facing towards us.”
(I don’t know if the article’s author(s) will read this, but I thought I’d correct the record for readers, too, who might not know this.)
Perfect ! Appreciate your knowledge…. 🙂
Nice
“What about a person inside the rocket? Is their size affected, too, by the same ratio?”
Yes. But the ratios differ depending on the observer.
An outside observer will see both the rocket and the passenger shrink, and in the same ratio.
The person inside the rocket won’t see any such contraction in size.
The contraction depends on the velocity relative to each other. Higher the relative velocity, more is the contraction.
Hydrogen and other Elemental Energy is Real Source for our climate change and Even For mars Colonized Theorem. We need to appreciate AND promote Space X Company. Because due to climate change our earth is more risky for humankind.
Transphobic, deadbeat dad, money-wendigo Elon is the problem, not the solution. If we can terraform the Moon or Mars into a livable and less risky environment, a second Earth, then I’m sure we can terraform Earth back into Earth. If we can’t because of human weaknesses like greed or overpopulation, then those same weaknesses will persist on the Moon and Mars, dooming them too, but faster than Earth, because they’re more fragile environments for life, subject to weakness. For example, compare the greed that promotes fossil fuels over greener tech development on Earth with the greed that would extract profits from people for water and oxygen on the Moon and Mars. We’re simply nowhere near the terraforming technology level and nowhere near the cultural maturity level required for living on the Moon or Mars as anything but an absolute nightmare. hth
I’m seeing twisted stuff when I’m tripping, too.
thank you for this