The James Webb Space Telescope: Is Our Universe Older Than 13.8 billion Years?
We are quickly approaching the second anniversary of the launching of the James Webb Space Telescope (JWST) on December 25th, 2021. Since the launch and start of operations, there has been a deluge of published papers which have excited both the public and professional astronomers. Located nearly 4 times further from the Earth than the moon, the JWST has peered into the depths of the cosmos offering great insights and presenting exciting questions.
Why is the JWST special? First it has a diameter nearly three times that of the Hubble Space Telescope (HST). Consequently, it has greatly increased resolution and is able to see objects nearly 9 times fainter than can be viewed with the Hubble (see above images). Also, it is observing at infrared wavelengths. Consequently, the telescope can penetrate the dust which obscures observations at visible wavelengths. This technology has pushed the boundaries of observational science and has presented new opportunities to test hypotheses and enhance our understanding of the cosmos.
The JWST’s discovery of unusually large galaxies in the early universe has sparked intense debate. Either galaxies form much faster than scientists thought or the universe is much older than 13.8. billion years! These speculations came about from a paper by Ivo Labbé et al, published early this year in the journal Nature, concerning large galaxies found using the JWST Near Infrared Camera (NIRCam), using long exposures to pick up distant galaxies.
The distant galaxies were identified in the first observations of the JWST Cosmic Evolution Early Release Science (CEERS) program. The CEERS program, using the JWST NIRCam, imaged an area of the sky to overlap with an existing HST image of a galaxy cluster known as SMACS 0723. As the above image shows, the JWST is capable of imaging far beyond the capabilities of the HST!
However, a complete spectrum from the light of the galaxies was not a part of the study, only images via filters. Consequently, an accurate distance of the galaxies observed could not be determined, but only inferred based on the data, as seen in figure 1 below. The inference of galaxy mass and distance came from using different filters for the light to determine the redshift of each galaxy. This, however, can lead to large errors and uncertainty because there can be large gaps in the wavelengths between the filters used. Unfortunately, the media can take over a story and publish wild headlines, such as the universe being twice the age it is believed to be, from 13.8 billion years to 26.7 billion years old!
A more recent paper by Pablo Arrabal Haro et al, in the journal Nature, follows up on a galaxy first measured as having a redshift (z) of 16.2. These authors found that the actual redshift was 4.9. Note how different Figures 1 and 2 are. In Figure 1 there are only 9 wavelengths with significant gaps between them whereas in Figure 2 there are many wavelengths without gaps. This suggests that the early measurements of distance of a few candidates can possibly be attributed to issues such as dust, which can make galaxies appear redder, and thus appear older than they are. With a redshift of 16.2, the galaxy would have emitted the light we see today when the universe was approximately 244 million years old, as opposed to a redshift of 4.9, which correlates to a universe that is 1.2 billion years old. With further analysis of the data and subsequent observations, we will gain a clearer picture of our universe. It is still too early to change our textbooks!
This is an exciting time for the field of astronomy, as the JWST allows for the testing of new ideas and presents new questions as we peer into the depths of the universe with greater resolution than ever before!
References:
Labbé et al. (2023) – https://arxiv.org/pdf/2207.12446.pdf
Haro et al. (2023) – https://arxiv.org/pdf/2303.15431.pdf
My thanks to George Roush for his review, insight, and improvements to this article.
