Astronomy & Astrophysics 101: Measuring the Age and Size of the Universe

Galaxy NGC 4603

Spiral galaxy NGC 4603 containing Cepheids being used for distance measurements. Credit: ESA/Hubble & NASA, J. Maund

How do we measure the age and size of the universe?

The search for Cepheids

The top-ranked scientific justification for building the Hubble Space Telescope was to determine the size and age of the Universe through observations of Cepheid variables in distant galaxies. This scientific goal was so important that it put constraints on the lower limit of the size of Hubble’s primary mirror. Cepheids are a special type of variable star with very stable and predictable brightness variations. The period of these variations depends on physical properties of the stars such as their mass and true brightness. This means that astronomers, just by looking at the variability of their light, can find out about the Cepheids’ physical nature, which then can be used very effectively to determine their distance. For this reason, cosmologists call Cepheids “standard candles.”

Astronomers have used Hubble to observe Cepheids with extraordinary results. The Cepheids have then been used as stepping-stones to make distance measurements for supernovae, which have, in turn, given a measure for the scale of the Universe. Today we know the age of the Universe to a much higher precision than before Hubble: around 13.7 billion years.

“We certainly live in exciting times. Hubble has made enormous progress possible within cosmology. Today we have a much more unified cosmological picture than was possible even five years ago when people were talking of ‘The Cosmology in Crisis’. We have seen a dramatic change from misery to glory!”

Gustav A. Tammann, Astronomer, University of Basel

Supernova 1994D in Galaxy NGC 4526

Pictured is the supernova of the type Ia star 1994D, in galaxy NGC 4526. The supernova is the bright spot in the lower left corner of the image. Credit: ESA/Hubble

The expansion of the Universe

One of Hubble’s initial ‘core’ purposes was to determine the rate of expansion of the Universe, known to astronomers as the “Hubble Constant.” After eight years of Cepheid observations this work was concluded by finding that the expansion increases by 70 km/second for every 3.26 million light-years you look further out into space.

Hubble’s sharp vision means that it can see exploding stars, supernovae that are billions of light years away, and difficult for other telescopes to study. A supernova image from the ground usually blends in with the image of its host galaxy. Hubble can distinguish the light from the two sources and thus measure the supernova directly.

For many years cosmologists have discussed whether the expansion of the Universe would stop in some distant future or continue ever more slowly. From the results of Hubble’s supernova studies, it seems clear that the expansion is nowhere near slowing down. In fact, due to some mysterious property of space itself, called dark energy, the expansion is accelerating and will continue forever. This surprising conclusion came from combined measurements of remote supernovae with most of the world’s top-class telescopes, including Hubble. Furthermore, recent supernova results indicate that cosmos did not always accelerate, but began accelerating when the Universe was less than half its current age.

Since Hubble’s measurement of the expansion of the Universe, there have been other more precise measurements, such as with the Spitzer Space Telescope. However, these different measurements haven’t been in agreement, causing a mystery and spawning new theories. New measurements with NASA’s Roman Space Telescope or from gravitational waves may help resolve the controversy.

The discovery of the accelerating expansion of the Universe led to three astronomers, Saul Perlmutter, Adam Riess, and Brian Schmidt, being awarded the 2011 Nobel Prize in Physics.

“Hubble gave us the distance measurements of the first four supernovae that made us realize something was wrong with our present understanding of the Universe. Even though the definite proof that the Universe is accelerating came later, we could not reconcile our Hubble observations with a Universe where the expansion is slowing down.”

Bruno Leibundgut, Astronomer, European Southern Observatory (ESO)

10 Comments on "Astronomy & Astrophysics 101: Measuring the Age and Size of the Universe"

  1. David Raften | May 29, 2022 at 5:58 am | Reply

    Good article, but it doesn’t address the discrepancy measuring the Hubble Constant using the Cosmic Microwave Background. 68 vs 70.

  2. Charles G. Shaver | May 29, 2022 at 6:49 am | Reply

    In my senior lay American male discoverer model of a universe in which gravity is locally induced to pulse in individual objects and cohere with all of the gravity of all of the objects in all clusters (e.g. from a single photon to supermassive black holes) to radiate outward in fields of consistently less dense coiled and spiraling lines of attractive force and, based on those same pulsing lines of local gravity force causing photons (minimally) to create the standard pattern of duality in double slit experiments, it stands to reason that photons will accelerate with expanding lines of gravity force when emitted from their sources and decelerate with contracting lines of gravity force after crossing the gravity neutral point between their sources and our solar system. Therefore, the farther a Cepheid variable is from the earth the more it’s photons can accelerate before crossing the gravity neutral point and begining to decelerate, causing an apparent higher average rate of travel assumed to be constant across the known universe and appearing to be accelerating away from the earth, in every direction. The big difference is I don’t adhere to the theory that the speed of light is constant, except within a particular field of gravity or light transmitting substance. The mystery to me is what exactly is inducing those pulsing lines of attractive force to radiate from all objects?

  3. BibhutibhusanPatel | May 30, 2022 at 3:16 am | Reply

    The accelerated expansion rate relative to the Hubble’s constant measured from galaxies near the milky way is due to rotation,that can be expressed in terms of dark matter.

  4. BibhutibhusanPatel | May 30, 2022 at 3:42 am | Reply

    Accelerated expansion rate is seen since half way from from the big bang in galaxies.Thus,a mean or mid point is present.So this fact is important as to grant the phenomena as basic property of the cosmos.

  5. Mike Pollock | May 30, 2022 at 4:31 am | Reply

    The discrepancy in the measurement of the the “expanding universe” exists because supernovae do not exist. Supernovae confuse the true entropy of all celestial objects. Stars do not blow up right in the middle of their lives. That is not rational. All of them began their history as black holes which are made of quark plasma, not gas and dust. This plasma systematically creates all the naturally occurring elements all by itself from the outside of the mass inward using the beta minus decay reaction. Supernovae were invented because the Big Bang theory only “created” three elements at the “beginning of the universe” and science had to “ad-hoc” a theory that would explain how the heavier elements were created. No scientist actually understands how supernovae work anyway. This faulty theory is why two different expansion rates exist since the actual life of a star is misinterpreted. The reality is that kinetic energy black holes follow the conservation of energy law by turning into potential energy rocks. It is just as simple as that.

    Edwin Hubble discovered the galaxies expanding, not the universe.
    13.8 billion years ago, our universe already existed. Space and normal matter already existed. The first law of thermodynamics proves that this statement is a fact. Science will never know where space and the normal matter came from because our universe has been here as long as it will be here. It is impossible for humans to deduce when it was “born”. Any attempt to do so is simply an exercise in religion to relate our universe to religion. Specifically, the religion of Genesis.

    There is a legitimate, law-abiding reason the galaxies are expanding. It is because the galaxies are shrapnel from a collision. Two objects, that contained the mass of the observable galaxies that already existed 13.8 billion years ago, simply collided in an already existing, static universe. This created quark plasma shrapnel that are the galaxies. This collision created a non-isotropic expansion of galaxies that will look like an expanding universe if it is mistakenly assumed that the universe is expanding. This whole problem is based on the misinterpretation of what Hubble discovered and he, and many of his colleagues as well, never accepted the interpretation Georges Lamaitre assumed because of the fact it sounded religious. They all knew more study needed to be done to explain the expanding galaxies but Lamaitre’s assumption was rushed into production as a fact with no consideration of the laws of physics at all. The scientist in this article stated “We have seen a dramatic change from misery to glory!” but that is not true at all. The misery still exists because dark matter, dark energy, black holes, supernovae, the muon and boson problems, gravity, and virtually every other observation ever made by scientists remains unexplained to this day. Scientists only state things like this to make their careers seem like that are actually accomplishing something when, in reality, nothing of any substance has been accomplished in the century since the Big Bang theory was made a fact.
    I have the true “Theory of Everything”. I know this because my theory follows all the laws of physics that were ignored to make the Big Bang theory a fact. The first law is satisfied because everything already existed when the Big Bang happened. The second law is satisfied because all the energy we see was produced from the pressure and friction from the collision and everything has cooled ever since. There is no ability for a cold cloud of gas and dust to turn itself into a star when there is no energy to perform such a task.

    Newton’s third law is satisfied because the “action” that caused trillions of galaxies to expand was the “reaction” from the collision creating shrapnel.

    How does the Big Bang theory explain any of these physics laws? Shouldn’t the theory be held accountable to explain how the laws are applied? If my theory follows all of them perfectly and the current theories do not explain anything at all, isn’t my theory not only a much better theory but, in reality, the only possible explanation?
    Einstein said “imagination is more important than knowledge”. Unfortunately, there is no more imagination in science. It is all about the “knowledge” that the Big Bang theory is a downright fact. Imagination is not allowed to be considered. Imagination is considered to be “crackpottery”. It is considered to be unscientific. Before I created my theory, I used the Big Bang theory for a year because that was all there was. I quickly realized that it was impossible to explain the myriad of problems using this lawless theory. Now, I have legitimate, law-abiding explanations for virtually every problem that exists including the problem of the “expanding universe discrepancy”. I can explain why fusion has never worked and never will. It is so easy to explain if the laws are followed. Our universe simply turned itself into a massive particle collider creating a non-isotropic expansion of matter that looks like an accelerating, expanding universe if it is mistakenly assumed that the universe is expanding. The “supernovae” that scientists are using to make the measurements simply do not exist. Any “supernovae” is simply an unfortunate star or black hole that was impacted by an object. Every single supernovae that scientists study don’t even possess the characteristics that they are supposed to. I know this for a fact because I’ve studied every one of them myself by reading the data on all of them. Besides, scientists admit that not nearly enough supernovae exist to explain the Big Bang theory anyway.

    It is obvious science is going to have a hard time rejecting everything that has been taught for 100 years. That is why paradigm shifts are so hard to realize no matter how much better the theory is. Everything has become a fact even though nothing is explained. Max Planck stated that no scientific community ever realizes any scientific truth and that it will always be one person that realizes the truth. That person is me because I went at all the problems without using the theory everyone is forced to adopt as a fact in their educations. I kept the Big Bang theory a theory and realized it is an impossible theory because of its desecration of all the laws. To this day, I don’t see how this theory has been allowed to survive so long. It is so unscientific that it is staggering that it exists.

    It is time for the scientific community to use my law-abiding theory. If the laws are followed, nothing can go wrong.

  6. If the Universe is infinite, then how is it possible to measure it’s size ?

  7. Tænkte på om det er muligt at den udadgående rotationskræft der er i en galakse som vil slyng stjernerne ud af galaksen hvis det ikke var på grund af tyngdekraften må det på en måde have en kraftig effekt på selvsamme så den kan være meget svlngene i styrke,kun en tanke.

  8. gerard van bekkum | May 31, 2022 at 7:16 am | Reply

    ik ben niet geïnteresseerd in de eindeloze wetenschap, vertel mij wat er is na het oneindige..hoe ziet en ervaart en omschrijft men het oneindige..dank, een simpele ziel

  9. The universe has no measurements or calculations. You cannot assume, guess or predict. Science knows nothing about the universe. It’s always been here, always has and always will. There are just no theories. Use your common sense

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