From: mk_thisisit
This article explores the concepts of spacetime, the nature of time, the possibility of time travel, and the physics of faster-than-light travel, drawing insights from recent advancements in physics.
What is Spacetime?
Spacetime is the fabric of our universe, a four-dimensional continuum that combines space and time. A new instrument being created in Poland is designed to examine our position in relation to spacetime [00:00:02].
Space itself is not an aether, as suspected for centuries, but rather possesses certain properties [02:52:00]. Spacetime can stretch and contract, and time flows differently depending on gravity and speed [03:00:00]. It should be treated as a coordinate system [03:18:00].
The Nature of Time
The concept of time is difficult to define [06:20:00]. We perceive time as a river flowing in one direction, though we are not fully aware of it [06:34:00]. Physics suggests that the passage of time is associated with matter; without matter, the concept of time loses its meaning [06:55:00]. As long as there is change, there is sense in measuring time [09:09:09].
The Beginning of Time
For decades, the beginning of time was believed to be the Big Bang [00:00:16]. This theory suggests that before the Big Bang, approximately 14 billion years ago, there was no time [16:26:00]. Some physicists believe we are not authorized to look into what happened before the Big Bang [16:33:00], while others believe time existed even before then [16:43:00].
Modern physics is moving slightly away from the sole Big Bang model for the origin of time [09:30:00]. The concept of a multiverse is gaining traction, where our known space might be one of many [09:50:00]. If we accept the existence of multiverses as coexisting bubbles that are created and end, the understanding of dynamics and change implies that time must also exist outside our specific universe [17:00:00].
A radical physicist, Julian Barbour, proposes that the entire universe is static, and our perception of change (and thus time) is merely the superimposition of our consciousness onto this static reality, where past, present, and future coexist [15:15:00]. This perspective suggests that from a theoretical standpoint, there is no distinct past, present, or future [15:45:00]. While mathematical equations might allow for the reversibility of the passage of time and the second law of thermodynamics, humans perceive time as irreversible due to entropy [15:52:00].
Some physicists even believe that the observed expansion of the universe is an illusion, and in reality, it is time that is expanding [17:32:00]. Time serves as a scale for measuring observations [17:48:00].
The End of Time
Physicists believe that time will eventually end [06:14:00]. This is based on the idea that when the universe is filled only with black holes, and they have absorbed all visible matter, there will be no more atoms in space [07:11:00]. At this point, the conversation about the passage of time loses its meaning, as there will be no matter or change to measure it [07:22:00]. Every star is thought to eventually become a black hole, and these black holes are increasing in number, eventually absorbing all matter and leaving the universe cold and empty [08:34:00].
Time Dilation and Relativistic Effects
Time is considered immutable, though some radical physicists believe it might not flow the same everywhere due to gravity and speed [10:52:00]. This is consistent with Einstein’s theory of relativity.
Time dilation is an effect where time flows slower closer to a mass (due to gravity) or when moving at higher speeds [03:09:00]. For example, time flows slightly faster on Mount Everest than at sea level [03:33:00]. This phenomenon can be observed in everyday life through the GPS satellite system [03:35:00]. Time on board GPS satellites, orbiting 20,000 km above Earth, flows faster, an effect that must be corrected daily to ensure accurate positioning [03:48:00].
Wormholes and Time Travel
For many years, wormholes were considered purely theoretical and beyond human reach [01:18:00]. However, physicists are now more open to the theoretical possibility of traveling with the help of space-time tunnels [01:30:00].
Quantum Entanglement
Space-time tunnels, particularly those created by the merger of two black holes, imply that these black holes must be completely entangled [02:15:00]. Entanglement is an inexplicable phenomenon where two particles behave in a consistent way; a change in the quantum state of one particle instantly affects the other [02:28:00]. In laboratory conditions, two particles must interact for entanglement to occur [02:48:00].
The challenge for time travel through space-time tunnels has been their perceived instability [03:09:00]. Inside, there’s a disruption where time and space exchange places, making it difficult to maintain stability and exit the other side [03:32:00]. However, recent significant progress in the quantum theory of the gravitational field suggests that with the right amount of information introduced into entangled black holes, stability might be maintained [03:13:00], though exiting from the other side remains beyond current civilization’s technical capabilities [04:59:00].
The Physics of Faster-Than-Light Travel
The possibility of achieving a speed greater than light has been a significant topic of discussion [00:00:11].
The CERN Neutrino Anomaly
Around a dozen years ago, there was much talk about potentially exceeding the speed of light [11:31:00]. An experiment between CERN and Gran Sasso, involving sending neutrinos, initially indicated that they arrived slightly faster than light [12:27:00]. This created a sensation, as it seemed to challenge Albert Einstein’s theory of relativity [11:52:00]. However, it was later discovered to be a technical error – the length of the optical fiber was incorrectly calculated [12:37:00]. Ultimately, Einstein’s theory remains valid [12:11:00].
White Rabbit Synchronization Protocol
In Poland, a synchronization protocol called “White Rabbit” was developed by engineers Tomek Włostowski and Grzesiek Daniel [12:49:00]. This protocol, highly accurate in distributing time patterns, impressed the world and is now used in the financial, energy, and scientific sectors, even being a candidate for quantum cryptography [13:16:00]. It was intended to help verify the CERN experiment, but the error was unrelated to its function [13:56:00].
Expanding Space vs. Expanding Time
While nothing with mass can travel faster than light, the universe itself can expand faster [18:42:00]. The observation that the oldest galaxies are moving away from us at speeds exceeding light, evidenced by their infrared shift, does not violate Einstein’s laws because it is space itself that is expanding [18:30:00].
Measuring Time
Atomic Clocks
Atomic clocks are critical for precise time measurement because they work the same regardless of geographical location, making them invaluable for the industrialization of space [24:43:00]. They function by counting the excitations of atoms, which vibrate very regularly [25:45:00]. The most precise atomic clocks, such as cesium fountains, operate in a vacuum and are cooled to ultra-cold temperatures, slowing down atomic movement to allow for extremely precise measurement [26:05:00]. These devices act like a magnifying glass for time, revealing events that would otherwise be immeasurable [26:30:00].
Optical clocks, which use photonics phenomena, represent the latest advancements in timekeeping, moving beyond atomic clocks [27:32:00]. A clock is fundamentally an oscillator, a counter that registers events with high regularity [27:47:00].
The Sagnac Interferometer
A highly sensitive instrument being created in Poland, known as the Sagnac interferometer, aims to examine our position in relation to spacetime [28:29:00]. It uses an optical fiber where light is released in two opposite directions, and their interference determines the device’s position not relative to Earth, but to spacetime [28:47:00]. This instrument can register changes in position with the accuracy of a helium atom’s nucleus [46:30:00]. It can even detect minute vibrations, such as tourists’ footsteps on the fourth floor of Książ castle, even from 100 meters underground [47:03:00]. Potential applications include non-invasive searches for gas and thermal water deposits [48:23:00].
The Double-Slit Experiment
The double-slit experiment demonstrates the wave-particle duality of light. When light from a bulb passes through two slits, a stripe spectrum (interference pattern) is created on a screen, indicating light’s wave nature [20:55:00]. With technological advancements, the experiment can be performed with single particles (photons or electrons), and surprisingly, the same stripe spectrum appears, even if particles are shot at very low frequencies (e.g., once every 10 years) [21:25:00].
This phenomenon puzzles physicists. Some explain it as the multiverse, where the photon follows all possible trajectories until a measurement is made [22:45:00]. What is most perplexing is that if photon detectors are placed behind the slits, the photon behaves like a particle, flying through only one slit and producing only two stripes on the screen [23:13:00]. Removing the detectors brings back the stripe spectrum [23:31:00]. This raises profound questions about the nature of reality and information transfer, which even theoretical physicists like David Deutsch have pondered for decades without finding an answer [23:38:00].
Time Synchronization and Space Industrialization
On Earth, universal time (UTC) is used, based on atomic clocks and adjusted with leap seconds to match astronomical time [41:42:00]. However, in the context of space industrialization (e.g., operating industrial automation on the Moon or Mars), current Earth-based timekeeping presents challenges [43:12:00]. Commands sent from Earth to the Moon experience a one-second delay [43:32:00]. There is a need to build consistent time scales and conversion systems for different celestial bodies, possibly through independent satellite systems around the Moon or strengthening existing Earth-based ones [44:05:00].
GPS receivers determine position and time by receiving signals from satellites. Initially, a receiver is in a state of uncertainty, but it synchronizes its internal clock by decoding radio messages from satellites [39:30:00]. By measuring the time difference between signal transmission and reception, and assuming the speed of light, the receiver can determine its distance from multiple satellites and thus its position [40:02:00]. GPS can be “spoofed” or hacked by transmitting false signals, a vulnerability especially for older receivers that were not designed with such threats in mind [35:18:00]. This vulnerability has been known in the financial sector for almost 15-20 years [37:07:07].