When we look back at the last century there's no denying that astronomer Edwin
Hubble's discovery of the universe's expansion is definitely the biggest finding in the field
of astronomy in the 20th century before that discovery we humans had no idea about how the
universe functioned and if it was eternal or had a beginning point what was its age
where was it coming from and where is it going Hubble not only discovered that the universe was
much much bigger than our milky way galaxy but there were many more galaxies out there as well
moreover these galaxies weren't just standing still that said he was never fully convinced
of the idea of a uniformly expanding universe he suspected his measurements might be evidence of
something odder going on in the universe and now almost a century later the findings of a
telescope named after him have shined an even brighter light on his seminal work
welcome to Factnomenal and today let's look at how three decades of space telescope observation
has shown us that something really weird is going on with the expansion rate of the universe
for decades after Hubble astronomers have labored to put a pin on the exact value of the expansion
rate that would reveal the true age of the universe when the Hubble space telescope was
launched in 1990 we were truly spitballing the universe's expansion rate and due to a
lack of data our guess back then was anywhere between 8 billion years and 20 billion years
scientists had to build a string of cosmic distance ladders where every step was assembled
from sources that scientists could reasonably trust regarding their intrinsic brightness
they shortlisted type 1a supernovae as the steps of these ladders as they're the brightest and
farthest detectable markers in space acting as beacons of the universe but with the data Hubble
has provided we've narrowed down the expansion rate to a precision of just over one percent
this is astonishing not only because of how much we've narrowed down the range of precision
but also because the Hubble telescope has outperformed our expectations the measurement is
about eight times more precise than was Hubble's expected capability moreover this is beyond just
crunching numbers thanks to Hubble we were able to discover the mystery of dark energy and its role
in the expansion of the universe with the help of this data we were also able to discern that the
expansion rate of the universe has drastically changed since the universe came into being with
the big bang now we have more questions that need answers and more answers that further raise even
more questions for example we can now predict that in the next 10 billion years the size of
the universe will double but there's a twist the Hubble telescope calibrated more than 40 mile post
markers out there in space time for over 30 years providing scientists with data that can precisely
calculate the universe's expansion rate on its mission the Hubble and other telescopes as well
found a strange twist a discrepancy between the expansion rate as measured in the local
universe compared to independent observations from right after the big bang which predict a different
expansion value well we're still trying to figure out what exactly the mystery is behind
this discrepancy Hubble's data supports the idea that something weird is going on based
on observations of a variety of cosmic objects that serve as distance markers this could be
a new branch of astrophysics that we're perhaps not even aware of yet Nobel laureate
Adam Reese of the space telescope science institute leads a scientific collaboration
investigating the universe's expansion rate called shoes which stands for Supernova H0
for the equation of state of dark energy their paper on the Hubble constant is the biggest
and likely the last major update to the expansion rate of the universe as they reanalyzed all the
old data sets and studied all the new information from Hubble and other telescopes including over
1,000 Hubble orbits the results were based on more than double the prior sample of cosmic data
markers one of the important objectives behind the development of the Hubble telescope was to resolve
the mystery of the cepheids cepheids are stars that brighten and dim periodically seen inside
our milky way and also in other galaxies cepheids have long been the gold standard of cosmic mile
markers since their utility was discovered by astronomer Henrietta Swann Levitt in 1912
to calculate much greater distances astronomers use exploding stars called type 1a supernovae
cepheids have played an important role in building that cosmic distance ladder we mentioned before
and thus they've been essential to measuring the expansion rate of the universe called the Hubble
constant after Edwin Hubble as we know without the Hubble constant we can't decipher the age
or a proper understanding of our good old universe the shoes team measured 42 of the supernova mild
post markers with the Hubble because they're seen exploding at a rate of about one per year
Hubble has for all practical purposes logged as many supernovae as possible for measuring the
universe's expansion Reese said we have a complete sample of all this supernovae accessible to the
Hubble telescope seen in the last 40 years like the lyrics from the song Kansas City from the
broadway musical Oklahoma Hubble has gone about as far as it can go but most importantly shoes
had an answer for us 73. no this is not the newly updated answer to the ultimate question
regarding life the universe and everything that answer is still 42 as far as we know 73 is the
estimated value of the Hubble constant according to shoes but see that's where the problem begins
the expansion rate of the universe was predicted to be slower than what Hubble actually sees by
combining the standard cosmological model of the universe and measurements by the European Space
Agency's Planck Mission which observed the relic cosmic microwave background from 13.8 billion
years ago astronomers predicted a lower value for the Hubble constant according to them it should
be 67.5 give or take point five kilometers per second per megaparsec not 73 as shoes estimated
this is a huge discrepancy according to rhys himself given the large Hubble sample size
there's only a one in a million chance astronomers are wrong due to an unlucky draw which is a common
threshold for taking a problem seriously in physics what was becoming a nice and tidy
picture of the universe's dynamical evolution has been unraveled by this startling discovery
astronomers are baffled and unable to come up with an explanation of the divide between the
expansion rate of the local universe against the primordial universe but the answer might include
a yet to be discovered layer of physics of the universe instead of getting disappointed reese
and other cosmologists are actually excited about this mystery 30 years ago they set out to measure
the Hubble constant to benchmark the universe and now it's become something much more interesting
there's also an additional method researchers have been trying to find better standard candles
than cepheids which tend to exist in crowded dust-filled regions that can distort estimates
of their brightness but according to astronomer Wendy Friedman of the university of Chicago
up to this point we've had no check on the cepheids and we need to have
better independent methods the continual interplay between applying our fundamental theories to what
we see and then having what we see come back and perhaps even modify our fundamental theories so
there may be so for example newton's laws hold up over in the solar system but when you get out to
greater distances you need Einstein's theory of relativity friedman has spent much of her career
improving the precision and accuracy of cepheid measurements but she and her colleagues are now
sidestepping cepheids all together instead using red giants as their standard candles red giants
are old stars that become puffed out together with supernovae explosions which serve as signposts for
more distant galaxies Friedman's team used the technique to calculate the distances to
18 galaxies and obtained an estimate of the Hubble constant that for the first time has accuracy
comparable with that of the cepheid-based studies however this study still relies on assumptions
about the amount of dust in galaxies particularly in the Large Magellanic Cloud which the study used
as an anchor point but space dust is tricky to estimate and the techniques precision will improve
as more data on red giants accumulates they could perhaps beat cepheids in the near future
yet this is not just about the age of the universe anymore now we're searching for an
unknown dimension of physics that has hidden its existence from us till now Hubble may be getting
too old for this but the James Webb telescope is going to pick up right where Hubble leaves off the
Webb telescope will add to the Hubble's work by showing these cosmic milepost markers at greater
distances or with sharper resolution than what the Hubble can see and maybe if we're lucky we'll see
something that we've never seen before the world of astrophysics is about to get bigger better and
broader tell us in the comments what you think what can we achieve by learning more about the
universe and as always thanks for watching Factnomenal and don't forget to like and subscribe