What the future looks like through the eyes of the James Webb Space Telescope
What the future looks like through the eyes of the James Webb Space Telescope
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  • 승인 2023.01.17 11:45
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International Astronomical Union XXXI General Assembly BUSAN 2022
Professor Brian P. Schmidt is being asked about James Webb Space Telescope. Photo: Kim Jung-A
Professor Brian P. Schmidt is being asked about James Webb Space Telescope. Photo: Kim Jung-A

The James Webb Space Telescope is currently overhauling the observation records set by GN-z11, which was formerly designated as 'the oldest galaxy' by the astronomical community. GN-z11 was discovered using the Hubble Space Telescope in the Ursa Major constellation in 2015. However, when the new James Webb Space Telescope entered the picture, everything changed. For example, the title of the oldest galaxy has changed hands three times over the past few months with new galaxies being discovered to have been created just 300 million years → 290 million years → 235 million years after the Big Bang. These galaxies, named GLASS-z11 and GLASS-z13, were discovered by astronomers at the Harvard-Smithsonian Center for Astrophysics, and although they are comparable to GN-z11, they have yet to gain mainstream attention.

So, why do people pay attention to old galaxies? It is to learn aboutᅠthe expansion of the universe. The universe has been expanding steadily until about 4 billion years ago when it started to expand at an accelerated rate. Evidence supporting the expansion of the universe include redshift, the mass ratio of hydrogen and helium, and cosmic microwave background radiation. Among these, cosmic microwave background radiation is a collection of various forms of electromagnetic waves in the universe. If one uses an optical telescope, the universe will look like empty black space, but if a radio telescope is used, one will be able to observe background radiation that are not related to stars.

The rate at which the universe expands is accelerating. The reason for this is dark energy. The existence of dark energy can be indirectly inferred through gravity, but it is a mysterious phenomenon that cannot be observed at all through means such as electromagnetic waves. In order to determine what dark energy is, we must first solve the error of the Hubble constant by determining an accurate value. The Hubble constant is the ratio of the velocity at which a galaxy moves to the distance between the galaxy and the observer. As the universe expands outward, the distance between stars gradually increases. Imagine that you draw two stars on a deflated balloon, then if you blow the balloon, the stars will move further apart. If you can calculate the expansion rate of the universe - that is, the Hubble constant - you can estimate the age of the universe by calculating it in reverse considering its size. In fact, according to the official results of the Hubble Constant Determination Project using the Hubble Space Telescope in 2001, the Hubble constant was determined as 72 km/s/Mpc, with a margin of error of 10%. At first glance, there seems to be no big difference, but there is a difference between the above value and the conclusions drawn using another independent measurement method that extends beyond the margin of error. The fact that this discrepancy has yet to be resolved is referred to as the 'Hubble conflict' or 'Hubble tension'ᅠ

The future of the universe is dark energy. Dark energy is absolute energy, and it accounts for 68.3% of the energy in the universe. On the other hand, stars and gas clouds that we can observe account for only about 4.9% of the entire universe. Most of them are interstellar dust or gases, and the substances that make up stars and galaxies comprise only 0.5% of the universe. The remaining 95 percent consist of dark energy and unknown substances called dark matter. Dark energy pushes the universe, but has no mass and is different in nature from wave-shaped energy like light. If the universe expands and the amount of matter in it remains constant, then the density should decrease as expansion progresses. However, dark energy maintains its power even as the universe continues to expand. Professor Brian P. Schmidt stated at the International Astronomical Union XXXI General Assembly BUSAN 2022 (IAUGA 2022) that "the universe will ultimately expand further from where we are today and will reach a point where everything is too far away to be seen. Eventually, if dark energy doesn't suddenly disappear, the universe will expand more and more rapidly and eventually disappear."

We live in a fast-paced society. From a thermodynamic perspective, this means that society is getting hotter than in the past. If the social temperature is low, order can be maintained with less energy, but if the temperature is high, much more energy is needed to maintain the same level of order. When this energy is scarce, society collapses. Society today is full of various forms of disorder in its larger populations and complex systems. Shocks from natural disasters, infectious diseases, and financial crises have already brought forth a global crisis. In the end, would we end up in a situation where the Earth becomes uninhabitable?

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