https://www.space.com/astronomy/how-fast-is-the-universe-actually-expanding-ripples-in-spacetime-could-finally-solve-hubble-tension

Robert Lea published another space.com article on March 2nd covering scientists’ discovery of a method to calculate the Universe’s rate of expansion. They say i’ts possible to use ripples in spacetime, or gravitational waves, to measure the rate of which our universe is expanding. This discovery could bring astronomers closer to solving the mystery of the Hubble tension, the disparity in calculating the rate of expansion. Since 2998, Scientists have known the universe is expanding at an accelerated rate. The unknown force causing the accewleration is called dark energy, and the Hubble constant is the unit of measurement. Scientists have been seeking a third way to measure the Hubble constant, and the answer to that, and resolving the Hubble tension, may lie in gravitational waves. Albert Einstein’s theory of gravity, general relativity, brought gravitational waves to the attention of the science and astronomy communities. General relativity suggests that objects with mass warp the fabric of spacetime. In correlation, objects that accelerate in spacetime, generate ripples that radiate outward at the speed of light, those ripples are the gravitational waves in question. Gravitational waves were first concretely detected in 2015, and as the technology to detect them improves, so will our understanding of how they relate to the expansion of the universe. The journey to unlocking all of the knowledge of the universe has been a long one and there is still so much to learn. 

We discussed how astronomers know the universe is expanding in the very last tutorial from the lecture tools textbook. Starting on page 197 in the section about the Big Bang. The diagrams presented show a universe that starts small and then expands, vs a large universe that did not expand with a small cluster of objects in the middle that spread out. We are asked to choose the correct one out of two students who are debating about the diagrams. The second student is right because they observed that diagram A had the only expanding grid. After this, a succession of diagrams, C, D, and E show the universe expanding. We drew an arrow from the youngest to oldest. We also went back to the first one and drew the very beginning, when the universe was just a dense, hot ball ready to burst. The universe is 13.7 billion years old, and this can be proven by the Hubble constant, with an equation of speed + distance divided by time.

Personally, I’m on board with the Big Bang theory and the idea that the universe is constantly expanding because of the evidence presented and I’m excited to see how much more evidence we collect for it in my lifetime. Reading this article and doing the tutorial sealed what I’d already agreed with for years at this point, ever since I’d first heard about it. I also believe in human evolution, and I think one of the most defining features of our world and universe is that they are constantly evolving.