The universe is full of mysteries, and one of the biggest is dark energy. But a new study suggests that a tiny supernova error could be the key to solving the 'crisis' surrounding this elusive force. But here's where it gets controversial...
Dark energy is one of those cosmological features that we are still learning about. While we can't see it directly, we can observe its effects on the universe - primarily how it is causing the expansion of the universe to speed up. However, recent results have shown that the expansion isn't happening at the rate our math would predict, leading some to question the very nature of dark energy.
A new paper from Dr. Slava Turyshev, who is also the most vocal advocate of the Solar Gravitational Lens mission, explores an alternative possibility. Instead of attributing the discrepancy to dark energy evolving over time, the paper suggests that our data is simply messy due to inaccuracies in how we measure particular cosmological features, like supernovae.
The debate stems from the Dark Energy Spectroscopic Instrument (DESI) releasing its second batch of data, known as DR2 in astronomy jargon. Previous papers had found a disconnect between DESI's new galaxy maps and the Cosmic Microwave Background (CMB), which is the leftover remnants of the Big Bang. One potential explanation for that mismatch is that dark energy is 'evolving' - either getting stronger or weaker over the course of billions of years.
But Dr. Turyshev argues that extraordinary claims require extraordinary evidence. He points out that if our measurements of supernovae are off, even by 0.02 magnitudes, it could explain the disconnect. Supernovae are commonly used for distance measurements at cosmological scales, so getting their brightness exactly right is critical to accurately measuring distance. And Dr. Turyshev, like many other astrophysicists, isn't sure our current crop of telescopes is up to that task.
Another potential point of error is the 'cosmic ruler' used in these scenarios. Known as the 'sound horizon', it measures the distance a clump of matter would move from its starting point out into the universe, but at a very specific speed - the speed of sound in the hot plasma that made up the early universe. These waves, known as Baryon Acoustic Oscillations, lasted for about 380,000 years before coming to a halt when the universe cooled down enough for the first atoms to form, essentially freezing them in place.
We use that distance as a ruler to measure distances to other things spread throughout the universe. But, since it is again a measurement, slight errors in the instruments used to calculate that measurement can introduce further errors down the line. To rectify this, Dr. Turyshev suggests a mathematical trick called the Alcock-Paczynski (AP) diagnostic. Instead of using the sound horizon, this technique uses a calculated shape of the universe that isn't reliant on fuzzy measurements of a certain point in the universe's early history.
If dark energy still seems to be fluctuating even after those checks are made, Dr. Turyshev has some potential answers as to why. He came up with a new one, called the Late-Transition Interacting Thawer (LTIT) model, which models how dark energy could 'thaw' after a certain amount of time after the universe started and is slowly beginning to interact with dark energy more and more, which is what we see as the expansion of the universe. Another potential explanation is known as the 'Phantom Crossing', where dark energy might become extremely powerful at some point, transitioning to what is called 'phantom' energy.
But if this theory is true, according to Dr. Turyshev, we will need a whole new set of physics to explain it, as it doesn't fit the standard model at all. Ultimately, we're still collecting more evidence on dark energy and all its associated mysteries. Luckily, even more data is coming, and some is already here.
Euclid, another cosmological probe, recently released its first data set, and astrophysicists are already poring over it in the hopes of shining some more light on this dark force in the universe. There's still plenty more discoveries left to come in this space, as DESI is also actively collecting data for its third data release, which will contain data from the first three years of the main survey, hopefully later this year. This research is available as a preprint on arXiv. This article was originally published by Universe Today.
