The connection of everything to time bending: from the speeding fly to Einstein

Time is not a simple thing: in physics, the rate of clocks depends on speed and gravity, while in the brain, the sense of time is influenced by attention, memory, and emotional state. A journey through flies, astronauts, and neuroscience shows where time really changes—and where only our experience changes.

We are used to talking about theזמן As if it were one cosmic clock, ticking at the same rate for everyone. But modern science presents a more complex picture. In physics, time is part of space-time and its measured rate depends on motion and the gravitational field. In the brain, however, the sense of time duration depends on mechanisms of perception, attention, and memory.

These are two very different phenomena, and they should not be confused. A fly that dodges an approaching insect is not a "time traveler," and a person who experiences an accident in slow motion does not change the laws of relativity. Still, the connection between them is interesting: in both cases it turns out that the simple concept of "how much time has passed" also depends on who is measuring, under what conditions, and in what system.

The fly doesn't stop time—it perceives changes faster

One of the most prominent examples of differences between animals is the Critical Flicker Fusion Frequency, or CFFThis is the rate at which the flashes are fast enough to stop being perceived as separate flashes and appear as continuous light.

Comparative studies have shown that small animals with high metabolic rates tend to have higher visual temporal resolution. In some species of insects and birds The visual system Able to notice changes much faster than a person notices them.

Therefore, when a hand approaches a fly, its visual system can provide very frequently updated information and enable a rapid escape response. The image of “slow motion” is useful for illustration, but it should be used with caution: there is no proof that the fly’s subjective experience is actually a slow motion movie. CFF measures the temporal resolution of the visual system, not the “speed of time” experienced by the animal.

For Einstein, time is truly not absolute.

בTheory of relativity According to Einstein's theory, a clock moving at high speed relative to an observer ticks more slowly than that observer's clock. In general relativity, gravity also plays a role: clocks in different gravitational potentials do not tick at the same rate.

These are not just theoretical ideas. In the famous Hepple and Keating experiment of 1971, atomic clocks were flown around the world in airplanes, and the time differences measured matched the predictions of relativity. Since then, accuracy has improved so much that in 2010, NIST researchers were able to measure a difference in the rate of optical clocks separated by less than a meter.

And what happens to the astronauts on the space station?

The International Space Station orbits the Earth at about 7.7 kilometers per second. The high speed causes clocks on it to lag slightly behind clocks on Earth. On the other hand, gravity is weaker at the station's altitude, so general relativity works in the opposite direction, causing the clock to run slightly faster.

In the low orbit of the space station, the effect of velocity is greater than the effect of gravity, so on balance, an astronaut who spends a long time in orbit will return a tiny fraction of a second younger than someone who stays on the ground. It's a difference too small to feel, but it's real and can be calculated and measured.

When you're afraid, time seems longer.

The human experience provides a completely different kind of “time bending.” People who have had accidents or falls sometimes report that a few seconds felt much longer.

Psychologist and researcher David Eagleman and his colleagues examined this phenomenon in an experiment in which subjects experienced a safe free fall from a great height. The participants retrospectively estimated that their fall had lasted longer than others' falls, but they did not find an increase in their ability to notice rapid visual information during the fall.

The conclusion was that the experience of "time slowing down" does not necessarily result from the acceleration of the perceptual system in real time. A possible explanation is that a frightening or unusual event is encoded in memory more richly, and when it is recalled, it seems longer.

Even "flying" time is a product of the brain

At the other extreme are moments when time seems to disappear. During concentrated work, creativity, play, or sports, people may enter a state known as “flow”—where attention is almost entirely directed to the task.

In such a situation, the physical clock of course does not change. What does change is the degree of attention we pay to tracking time. So an hour may feel like a short moment, while waiting a few minutes without doing anything may feel very long.

Biological clocks and navigation in nature

In the animal world, too, time is not just a matter of vision. Circadian rhythms synchronize activity with cycles of light and darkness, influencing sleep, foraging, migration, and reproduction. In migratory birds, internal time mechanisms combine with various environmental cues—including the position of the sun, stars, and the Earth’s magnetic field—to time and direct long journeys.

Here it is important to note again: the biological clock does not "measure relativity," and the magnetic field does not set the pace of time. These are different systems that evolution has combined to solve problems of timing and orientation.

So what really "bends"?

The answer depends on what time we are talking about.

In physics, the theory of relativity states that the interval between events is not absolute and uniform for all observers. Velocity and gravity measurably change the rate of clocks.

In biology and psychology, physical time does not change, but the way the nervous system samples information, directs attention, encodes memories, and estimates durations can vary greatly.

Maybe here we find it."The connection of everything": Not that all phenomena are the same, but that one everyday concept—time—takes on a different meaning when one moves from physics to the visual system, from the brain to memory, and from humans to other animals.

Questions and Answers

Does a fly really see the world in slow motion?

Not in the sense that time itself moves slower for him. The visual system of Flies and other insects are able to perceive changes more rapidly than humans, so the image of slow motion could help explain their reaction advantage. It is not evidence of a subjective experience of slow time.

Does time really pass more slowly for astronauts?

Yes, in the physical sense of relativity. The high speed in orbit slows down the clock relative to the clock on the ground, while the weaker gravity works in the opposite direction. On the space station, the overall effect is very small but measurable.

Why do moments of fear sometimes seem longer?

An experiment by Eagleman and colleagues found no improvement in temporal resolution during a frightening event. The more likely explanation is a change in the way the event is perceived and remembered, making it seem longer in retrospect.

What is the difference between physical time and subjective time?

Physical time is measured by clocks and described by the laws of physics. Subjective time is our experience of the duration of time, and is influenced by attention, emotion, memory, and sensory processing.

Scientific sources

• Metabolic rate and body size are linked with perception of temporal information — Animal Behaviour, 2013
• Does Time Really Slow Down During a Frightening Event? —PLOS ONE, 2007
• Around-the-World Atomic Clocks: Predicted Relativistic Time Gains — Science, 1972
• Around-the-World Atomic Clocks: Observed Relativistic Time Gains — Science, 1972
• Optical Clocks and Relativity—Science, 2010
• Long-distance navigation and magnetoreception in migratory animals — Nature, 2018

More on the subject on the science website

• From dragonfly to starfish: Why don't animals see time at the same pace?
• Happy Birthday Einstein: Can we feel the dilation of time from the theory of relativity?
• Einstein — the man who began to take us out of the Matrix: There are gravitational waves
• The complete guide for the time traveler
• Time in a side view

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