“This is not some fringe idea, where a few contrarian scientists are overemphasizing a small difference in the data. If both groups are correct — and no one can find a flaw in what either one has done — it might be the first clue we have in taking our next great leap in understanding the Universe. Nobel Laureate Adam Riess, perhaps the most prominent figure presently researching the cosmic distance ladder, was kind enough to record a podcast with me, discussing exactly what all of this might mean for the future of cosmology.
It’s possible that somewhere along the way, we have made a mistake somewhere. It’s possible that when we identify it, everything will fall into place just as it should, and there won’t be a controversy or a conundrum any longer. But it’s also possible that the mistake lies in our assumptions about the simplicity of the Universe, and that this discrepancy will pave the way to a deeper understanding of our fundamental cosmic truths.”
In science, if you want to know some property of the Universe, you need to devise a measurement or set of measurements you can make to reveal the quantitative answer. When it comes to the expanding Universe, we have many different methods of measuring light that fall into two independent classes: using the imprint of an early relic and using the cosmic distance ladder. These two techniques each give solid results that are mutually inconsistent: the distance ladder teams find results that are higher than the early relic teams by about 9%. Since the errors are only about 1-2% on each measurements, this has been dubbed cosmology’s biggest controversy.
But perhaps it’s not about “who is right,” but rather about “what is the Universe doing?” Perhaps it’s a clue, not a controversy. Come learn about the cutting-edge science behind this fascinating and unexpected result.
washing the dishes
making your bed
tidying your book/dvd shelf/shelves
cleaning the cupboard/wardrobe
reading
sleeping
writing a blog
planning your month/week/day
replying to messages or asks
responding to emails
sorting through letters/mail
clearing your email inbox
organising stationery
clean your sinks
clean your toilets
pet your pet
sort through old clothes
give to charity
go on a walk
go on a run
clean down any surfaces
work out
meal prep
get rid of empty shampoo bottles from the shower
clean out old food from the cupboard/fridge
empty out your school bag
call your parent
unfriend/unfollow people you no longer interact with
watch a TEDTalk
empty the bins/trash
clean the mirrors in your house
hug your pet
wash some clothes
buy any birthday cards/presents that you need to
reply to any old texts
make a tumblr post on productive things that aren’t studying
“Finally, there are the wavelength limits as well. Stars emits a wide variety of light, from the ultraviolet through the optical and into the infrared. It’s no coincidence that this is what Hubble was designed for: to look for light that’s of the same variety and wavelengths that we know stars emit.
But this, too, is fundamentally limiting. You see, as light travels through the Universe, the fabric of space itself is expanding. This causes the light, even if it’s emitted with intrinsically short wavelengths, to have its wavelength stretched by the expansion of space. By the time it arrives at our eyes, it’s redshifted by a particular factor that’s determined by the expansion rate of the Universe and the object’s distance from us.
Hubble’s wavelength range sets a fundamental limit to how far back we can see: to when the Universe is around 400 million years old, but no earlier.”
The Hubble Space Telescope, currently entering its 30th year of service, has literally revolutionized our view of the Universe. It’s shown us our faintest and most distant stars, galaxies, and galaxy clusters of all. But as far back as it’s taken us, and as spectacular as what it’s revealed, there is much, much more Universe out there, and Hubble is at its limit.
Here’s how far we’ve come, with a look to how much farther we could yet go. It’s up to us to build the tools to take us there.
“As we look farther back in time, we find that younger galaxies formed stars at faster rates than galaxies do today. We can measure the star-formation rate, and find that at earlier and earlier times, it was more intense. But then we find it hits a peak when the Universe is about two billion years old. Go younger than that, and the rate goes down again.”
We’ve come incredibly far in our quest to learn how the Universe came to be the way it is today. We can see out in space for tens of billions of light years, to galaxies as they were when the Universe was only a few percent of its present age. We can see how galaxies evolve, merge and the stars inside change. And we can see to even before that, when no stars or galaxies existed at all. But how did we get from there to here? There are still plenty of gaps in the story. We’ve never seen the first stars or galaxies; we’ve never witnessed the start of cosmic reionization; we’ve never seen the star formation rate jump from zero to a real, finite number. Yet with James Webb and WFIRST on the horizon, these gaps in our knowledge may – if we’re lucky – all disappear.
Come get the story on what we know about the first galaxies, and what we hope and have left to still learn!