While these extensions to the standard model relieve the Hubble tension, they are regarded by many cosmologists as fine-tuned — opportune mathematical additions that have no clear justification.
For example, most cosmologists think space exponentially expanded at the start of the Big Bang during a period known as inflation, which was driven by a different kind of dark energy than the one that exists today.
But in a preprint submitted to Physical Review D in March, Barker and three co-authors acknowledge that much more analysis is needed to see if the model can describe not only how the universe expands but also how structures like galaxies and clusters evolved. With contemporary telescopes offering a glut of impressively precise data on such structures, devising a theory that matches all the observations is no mean feat. Even with the extra freedom, most of the nonstandard models only reduce the Hubble tension rather than eliminating it.
In the coming years, the Euclid telescope and others will meticulously map how gravity and dark energy have shaped cosmic evolution. Meanwhile, gravitational waves emitted from colliding neutron stars offer a new way to measure the Hubble constant. The new data will rule out some of these novel solutions to the Hubble tension, but new cracks in the standard model may appear.
For now, many cosmologists are loath to complicate the model when it otherwise works so well. She added that even if the Hubble tension turns out to be nothing more than an accumulation of errors, this search for new physics may not be in vain. And how much can we change things? This article was reprinted on Wired. By studying infrared wavelengths, it will allow better measurements that won't be obscured by the dust between us and the stars. If they find that the difference in the Hubble Constant does persist, however, then it will be time for new physics.
And although many theories have been offered up to explain the difference, nothing quite fits what we see around us. Each potential theory has a downside. For example, it might be there was another kind of radiation in the early universe, but we have measured the CMB so accurately this does not seem likely.
Another option is that dark energy could be changing with time. It has forced scientists to dream up new ideas that could explain what is going on.
Depending on what these new telescopes reveal, Beaton and Freedman could well find themselves in the midst of a mystery worthy of an Agatha Christie novel after all. Join one million Future fans by liking us on Facebook , or follow us on Twitter or Instagram. If you liked this story, sign up for the weekly bbc. The mystery of how big our Universe really is. Share using Email. By Abigail Beall 29th March The cosmos has been expanding since the Big Bang, but how fast?
The answer could reveal whether everything we thought we knew about physics is wrong. Two competing forces — the pull of gravity and the outwards push of radiation — played a cosmic tug of war with the universe in its infancy.
Download references. News 09 NOV News 17 SEP Obituary 06 AUG Temple University. Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily. Advanced search. Skip to main content Thank you for visiting nature. You have full access to this article via your institution. Download PDF. References 1. Close banner Close. The peculiar curvature of space predicted in the equations was quickly endorsed in famous experiments, and by the early s most leading scietists agreed that Einstein's field equations could make a foundation for cosmology.
I have erected but a lofty castle in the air So let us be satisfied and not expect an answer, and rather see each other again as soon as possible! EXIT to read more about Einstein's general theory and the observations that made it famous. Einstein's first try at a model likewise could not contain matter and be stable. For the equations showed that if the universe was static at the outset, the gravitational attraction of the matter would make it all collapse in upon itself. That seemed ridiculous, for there was no reason to suppose that space was so unstable.
E instein found he could stabilize his model by adding a simple constant term to the equations. If this constant was not zero, the model would not have to collapse under its own gravity. This "cosmological constant," Einstein admitted, was only "a hypothetical term. The introduction of such a constant implies a considerable renunciation of the logical simplicity of the theory Since I introduced this term, I had always a bad conscience I am unable to believe that such an ugly thing should be realized in nature.
Vesto Slipher. How Slipher could measure velocities in the heavens. Spiral Nebula in Ursa Major M. T he powerful belief in a static universe could only be overturned by the weight of accumulating observations. The first of these observations had already been reported in Probably the observation was unknown to Einstein when he was developing his theory and corresponding with de Sitter.
World War I had disrupted communications between the English-speaking nations and Germany, where Einstein worked, while de Sitter had only a second-hand, incomplete report of the crucial observation. The observation had been made at the Lowell Observatory in Arizona.
Its founder, Percival Lowell, suspected that spectral lines seen in the light from one species of nebula, the "planetary" nebulae, might also be found in the spectra of spiral nebulae. In Lowell asked his assistant Vesto Slipher to get spectra of spiral nebulae. Slipher initially doubted that it could be done. W ith a new camera, its speed increased by a factor of 30, on the night of 17 September Slipher obtained a spectrogram for the Andromeda Nebula.
The spectrogram indicated that the nebula was approaching the solar system at an amazingly high velocity. Slipher made more observations, exposing the same photographic plate over multiple nights for example, 29, 30, and 31 December That was so large that some astronomers did not believe it possible. Over the next two years, Slipher measured velocities for other spiral nebulae. The first few measurements revealed approaching nebulae on the south side of our galaxy and receding nebulae on the opposite side.
Slipher formed a "drift" hypothesis. He thought that it was our galaxy that was moving relative to the nebulae, toward the south and away from the north. However, observations of more spirals contradicted this. Receding spirals were found on the south side of our galaxy as well as on the north side. Slipher nevertheless clung to his drift hypothesis.
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