In anticipation of my next public lecture, the organizer asked the title of my lecture. I suggested: “Hunting aliens.” The organizer expressed his concern that some members of the audience can confuse me for an American government officer looking for illegal alien beings in the vicinity of the southern border wall. I explained that no two -dimensional wall on earth would protect against alien beings because they will arrive from above.
It’s just a matter of time until we notice that interstellar travelers arrive without a good visa. A policy to deport them back to their home exoplanet will be expensive – more than a billion dollars per flight. The journey will also take a long time – for a billion years with conventional chemical propulsion. We will have to learn how to live with these aliens and promote diversity and inclusion in a galactic context.
The sun was formed in the last third part of cosmic history, so we are relatively late for the party of Interstellar travelers. Experienced travelers may have been busy with their interstellar journeys for billions of years. To properly interpret their recorded diaries and photo albums in terms of the specific stars they visited, we should accurately interpret their time measurements.
Imagine an interstellar tourist who wears a mechanical analog watch. Such a timepiece is at best accurately up to 3 seconds a day, or equivalent 30,000 years per billion years. This timing error is similar to the amount of time needed to jump from one star to the other with chemical propulsion. Interstellar travelers must wear better clocks to have a reliable record of time.
Our best atomic clocks are accurate for a fractional uncertainty of approximately One billionth of one billionth. They use the natural transitional frequency of atoms, such as Ytterbium. Transitions with a higher frequency ensure greater precision. This was recognized in A recent articleWhat suggested the use of nuclear transitions in future clocks.
What is the ultimate precision feasible through clocks? In the context of our current understanding of quantum mechanics and gravity, there could be no transition between discreet quantum states in which the emitted particle carries more than the Planck energy. Distributing this maximum energy by the constant of Planck yields the maximum frequency of each clock. This suggests that no clock could use a timing cycle shorter than the opposite of the Planck frequency, 5.4 × 10^{-44} seconds. The age of the universe is 8 × 10^{60} Planck units.
Because every clock cycle offers an independent measurement, the Central limit In statistics, the temporary precision of a clock could improve reversed with the square root of the number of cycles. A Planck clock that works all over the cosmic history would at best reach a precision of 4 × 10^{-31} Planck times or 2 × 10^{-74} seconds. This is good enough for all practical purposes of interstellar travel.
So far we have assumed that time is continuously as posted in modern physics. But what if time is achieved as a series of discreet points? We would not notice the difference between these cases if we use a clock that cannot solve the discreetness of time, because the inherent timing errors introduce fuzziness, which means that the discreet time steps appear as a continuous order. When investigating a collection of atoms with poor spatial resolution, much larger than the separation between the atoms, the system appears as a continuous liquid. When watching a film with a frame speed that exceeds the sample speed of our visual sensory system, the film seems continuous. In reality, the film is a collection of snapshots.
Is the reality a collection of snapshots?
Since the speed of light is a universal constant, discretion over time translates into discreetness of space. The spatial pixel length is the temporary pixel -expensive times the speed of the light.
Computers simulations use discreet pixels in space and time. If our world is a computer simulation, such as suggested In 2003 by the philosopher Nick Bostrom, then improved clocks could eventually solve the discreet intervals of the simulation. Accurate clocks would detect a physical reality that consists of snapshots, in which nothing happens between discreet time steps.
A film guard with an exceptionally high sampling speed will see a series of snapshots. For the same reason, future clocks can reveal experimental that we live in a simulation. But winning the Nobel Prize for Physics for such a discovery will not be particularly satisfying, because the price ceremony is part of the simulation and not really in a meaningful way. The discovery must be choreographed by the maker of the simulation.
Here it is hoped that our interstellar visitors will wear a Planck clock that would show the best possible precision that time is continuous and that we do not live in a simulation. In that case, the reality of their visit would feel much better than a Hollywood script for an artificial order of snapshots.
But there is also a cultural nuance for our future encounters with alien beings. The way we express the age of the universe as a 13.8 billion years reflects our anthropocentric worldview, in which we document the cosmic history based on the orbital period of our home planet around the sun. Aliens can use the orbital period of their home planet. Keep that in mind when scrolling their photo albums in chronological order.
