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Review
What is time? This question may sound abstract, but it is one of the oldest and most thought-provoking questions in human history.
Throughout the ages, human beings have been searching for the essence of time and seeking its meaning. And now, with the help of advanced scientific and technological means, a space telescope named Webb has brought us a subversive answer: there may be no time in the universe!
What is Webb Telescope?
The James Webb Space Telescope (JWST or Webb), one of the crystallization of human space technology, was launched on December 25, 2021, and flew to the L2 orbit of the Lagrange point, which is about 1.5 million kilometers away from the Earth.
As the result of trilateral cooperation between the United States, Europe and Canada, the Webb telescope is not only the successor of Hubble, but also one of the most advanced, complex and expensive space telescopes in human history.
The space tech giant is unique in its massive gold-plated mirror, up to 6.5 meters in diameter, made up of 18 hexagonal lenses capable of capturing seven times more light than Hubble.
In order to maintain the telescope's operating temperature below -233°C, the Webb telescope is also equipped with a 250-square-meter solar sail to shield it from the thermal radiation of the Sun, Earth and Moon.
The Webb telescope, which focuses on the infrared light band, is designed based on the characteristics of the expansion of the universe. The wavelength of light in distant galaxies is elongated due to the expansion of the universe, changing from visible light to infrared light.
This allowed the Webb telescope to look deep into the early stages of the universe, even hundreds of millions of years after the Big Bang, opening up the possibility for humans to explore the origin and evolution of the universe.
The Webb telescope's observations reflect the evolution of the universe and the notion that these changes take time. From the data of the Webb telescope, we can get a glimpse of the different periods that the universe has gone through since the Big Bang, such as the era of dark energy matter, the era of reionization, and the era of galaxy formation. These periods represent how matter and energy in the universe have evolved over time.
For example, dark energy is a mysterious force that accelerates the expansion of the universe, and dark matter is a substance that can only be directly observed through gravity.
The era of reionization saw the transition of the universe from opaque to transparent, while the era of galaxy formation marked the stage in which stars and galaxies flourished in the universe.
All of these periods highlight the importance of time, as they constitute a description of the sequence and continuity of events, without which there would be no history and future of the universe, no changes and development of the universe.
What is time?
Time is a complex and fascinating concept that has been defined differently in different disciplines and fields. In physics, time is seen as a measure that describes the sequence and continuity of events, and together with space, it forms space-time and becomes a fundamental part of physical phenomena.
- In the field of psychology, time is regarded as a kind of subjective perception of human beings, which is closely related to memory, attention, emotion and other factors, and different individuals may have different perceptions of time in different situations.
- Philosophically, time is considered to be a mode of being, involving issues such as causality, free will, eternity, etc., and different philosophical schools have different views on the nature and meaning of time.
There are several main views on the modern perception of time:
- Newton's Absolute Time: This classical view holds that time exists objectively, is not affected by matter and space, and does not change due to the movement of the observer. Newton likened time to a constant-flowing "river" that is not disturbed by external forces.
This view is a good way to explain and predict simple physical phenomena such as planetary motion, clock timekeeping, spring vibrations, etc. However, there are many contradictions between this and many of the theories that have been put forward since then, as well as the results observed through experiments.
- Relativity: This revolutionary view holds that time is relative and changes with matter, space, and observer motion. Einstein unified time and space to construct a curved four-dimensional space-time structure influenced by matter and energy.
While it is good at explaining complex phenomena such as black holes, gravitational waves, and nuclear reactions, it also raises problems of causality, such as time travel, closed space-time curves, and faster-than-light communication.
- Hawking's arrow of time: This modern view holds that time has a direction and flows into the future due to the increase in entropy in the universe. Entropy indicates the degree of disorder of the system and is an irreversible process.
Hawking linked the direction of time to an increase in entropy, forming an arrow of time that indicates the direction of events in the universe. Although it can explain and predict thermodynamic and statistical physical phenomena such as heat conduction, diffusion, and mixing, it ignores the possibilities of quantum mechanics.
- Carl Sagan's Cosmic Calendar: This popular view holds that time is a scale used to measure the history and future of the universe.
Carl Sagan compresses the age of the universe (about 13.7 billion years) into one year, and vividly describes the time and sequence of events in the universe. Although cosmological knowledge can be popularized and disseminated, and an intuitive impression can be formed, it is only an artificial division that does not reflect the true time scale and flow of the universe.
There may be no time in the universe
As the Webb telescope continues to send back data from its observations to scientists, some have made a startling suggestion that the universe may run out of time.
They believe that there are many inconsistencies between these data and our current understanding of the universe, mainly in the following aspects:
- Differences in the propagation time of light: The early cosmic light observed by the Webb telescope came from more than 13 billion light-years away from us, and the time spent on light exceeded the age of the universe (about 13.7 billion years).
This raises the question of whether these galaxies already existed when the universe was born, or whether light was produced when the universe first formed. This is inconsistent with the Big Bang theory, which holds that the universe originated from an infinitely small, infinitely dense, infinitely hot singularity in which there is no space and no time.
- Redshift and expansion velocity: The early cosmic light observed by the Webb telescope is infrared, suggesting that the expansion of the universe has led to an elongation of the wavelength of light in distant galaxies.
This raises questions about whether the rate of expansion exceeds the speed of light. The theory of relativity holds that no matter or information can exceed the speed of light, otherwise the law of cause and effect would be violated. If the universe expands faster than the speed of light, we will not be able to see the boundaries of the universe and determine the size and shape of the universe.
- The Problem of Cosmological Isotropy: Observations show that the early universe is in an isotropic state, i.e., homogeneous, homogeneous, and flat, which does not correspond to the various structures and differences that exist in the universe.
There are countless celestial bodies in the universe, all of which have their own very different compositions, and all have their own characteristics and laws. If the early universe were homogeneous, there would be a lack of entropy, and it would be impossible to explain the degree of disorder in the universe and the existence of the arrow of time.
Based on these ideas, some have concluded that there may not be time in the universe, and that time is just a tool created by our brains to understand and interpret the universe. They assert that time is an artificial concept that has no objective existence and meaning, but is only a product of our perception and imagination.
epilogue
In fact, not only time, but all human scientific systems are based on our own language, describing the world in a way that we can understand.
With the development of technology, it is not very surprising that some previous language was not rigorous or incorrect. After all, science is always evolving, and the research of future generations is always patching up for their predecessors. We should not be afraid of subverting ideas, as long as we can always maintain the spirit of exploration.
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