Analysis Of Down To Earth Magazine: ”Our Cosmic Roots”

Relevance

”GS 3: Space Technology”

Context

Recently, the James Webb Space Telescope (JWST) or Webb opened its 18 golden mirrors to the universe and captured its first image—of a sun-like star called HD-84406, some 260 light-years from the Earth.

When the telescope was launched?

• The telescope was launched on December 25, 2021.
• It took 30 days to travel 1.5 million km from Earth in a direction opposite to the Sun to reach its destination—a gravitationally stable point named L2—from where it will orbit the Sun, slightly changing its position every three weeks to stay in a halo orbit.
• NASA states the aim of the telescope is to examine the formation of galaxies and the evolution of our own solar system.

About James Webb Space Telescope (JWST) or Webb

• US space agency NASA took 30 years to build the telescope.
• The telescope was named after NASA’s second administrator James E Webb.
• JWST in its formative stages in the 1990s was called the Next Generation Space Telescope.
• It is based on infrared light and can see events from 13.5 billion years back in time.
• This is right after the Big Bang, when a single, unimaginably hot and dense point called the singularity exploded to form the Universe.
• Its observations of the earliest galaxies could be instrumental in understanding life today.

James Webb Space Telescope (JWST) vs Hubble Telescope

• Webb often gets called the replacement for Hubble but actually it’s a successor.
• Webb’s science goals were motivated by results from Hubble.
• Hubble’s science pushed us to look to longer wavelengths to “go beyond” what Hubble has already done.
• In particular, more distant objects are more highly redshifted, and their light is pushed from the UV and optical into the near-infrared.
• Thus observations of these distant objects (like the first galaxies formed in the Universe, for example) requires an infrared telescope.
• This is the other reason that Webb is not a replacement for Hubble; its capabilities are not identical.
• Webb primarily looks at the Universe in the infrared, while Hubble studies it primarily at optical and ultraviolet wavelengths (though it has some infrared capability).
• Webb also has a much bigger mirror than Hubble.
• This larger light-collecting area means that Webb can peer farther back into time than Hubble is capable of doing.
• Hubble is in a very close orbit around the earth, while Webb will be 1.5 million kilometres (km) away at the second Lagrange (L2) point.

Why should we know about the early universe?

• learning about the very early universe is still an important goal because it traces our cosmic roots.
• One of the biggest mysteries in the study of the cosmos is: What happened before the Big Bang? Einstein’s theory of gravity breaks down at the singularity of the Big Bang. We currently do not have a working theory that unifies quantum mechanics and gravity that could take us through that singularity.
• Some people are also searching for clues about the very beginning in the cosmic microwave background (residual electromagnetic radiation from an early stage of the universe) and in the distribution of galaxies.
• Of course, there is also the question of how and when the stars and galaxies formed.
• We, humans, are possible thanks to heavy elements like carbon or oxygen that were produced in stars, not the Big Bang. So tracing our cosmic roots will bring us to the period when the first stars formed and enriched the environment with heavy elements. In a way, it’s the scientific version of the story of Genesis.

Conclusion

JWST could be helpful in measuring the expansion rate of the universe versus cosmic time, by looking at very distant supernovae. This would allow us to set limits to detect dark energy evolution over time, and in much the same spirit also set limits on dark matter. The more data we get, the better our limits on nature can be.