Astronomy

Age of the universe

Age of the universe


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A Galactic year is estimated to be around 250 million "terrestrial" years. That means there will be about 4 rotations per billion years. And age of the universe is estimated to be near 13.8 billion "terrestrial" years. It looks improbable to think that our galaxy has rotated 50 times since the beginning of time. Could someone explain this please?


Your calculation sounds correct. It is however based on assumptions that are non-trivial. An analogy with the Earth would give that the Earth rotated around the Sun 13.8 billion times since the Big Bang. Which is meaningless since the Earth was created only a few billion years ago. Our galaxy, the Milky-Way, may have had a long and quiet history since 10 billion years ago (http://arxiv.org/abs/astro-ph/0702585), which is not too far from the age of the Universe. Our Galaxy, however, evolved, and its rotation speed too. As for the solar system, the duration of a "year" (ie one rotation over the Sun) on Earth is very different from the duration of a "year" on other planets. It is the same in the Milky Way where the revolution period is different depending on the distance from the center of the galaxy. As an order of magnitude, and considering in first approximation that our Galaxy is old, and that its properties did not change too much, an order a magnitude of a few tenths revolutions since our Galaxy is a stable disk sounds plausible. As a first approximation. I hope this will help you to find that such a value is not improbable.


Currently Astronomy relates to Time in a manner similar to the Geocentric / Heliocentric syndrome that plagued early Astronomers that did not have enough information available to accurately describe how the Solar System maneuvered.
Earthlings use Time as it relates to Earth to measure the Age of Celestial objects because we don't currently understand how Time works. More specifically we use the J2000 epoch to tell time on Earth because it was designed hundreds of years ago, appears to work for the time being and is commonly agreed upon.
The problem is that we believe our planet is approximately 4.5 billion years old and a year is an approximate amount of time that is consistent over long periods of time. So we extrapolate out and use that to measure objects outside our system since that is the only reference point we know and understand and we do not have access to a Time system that explains other Systems and is capable of measuring them.
The Universe if it is the largest encapsulating structure needs its own time system that starts from its origin and is consistent to measure against other systems. For example using a second instead of a year (presuming a second takes the same duration in all systems).
A Galaxy would need its own Time reference from its origin with in the Universe using a similar consistent standard like a second so you could accurately compare their ages. If you just look at the Earth year we don't know how long a year was a billion years ago, it may have only been 100 days and we don't know how long one will be in a billion years, it may be 1000 days, just to make an example. So an Earth year is a poor way to measure the age of other Celestial objects but it is the best we have at the present time so we continue to use it. Technically we shouldn't be able to measure anything older than approximate 4.5 billions years because theoretically that time doesn't exist because Earth didn't exist. You can see how this resembles the Geocentric / Heliocentric problem.
In the future we will realize the J2000 epoch is based on the birth of Jesus Christ and that we are not accurately measuring time on our own planet based on its beginning but rather basing it on an individuals life. At some point we will agree on a common starting point for the planet and develop technology to determine that moment similar to how we developed carbon dating.
You can see how this will even effect the term light year as we realize the length of a Earth year changes over long periods of time and is not accurate to measure distances that light travels relating them to orbital period of our planet. Note also light appears to travel a linear fashion whereas our planetary orbit is circular. The key would be to have a time standard that is linear in fashion as well.
Your point about how many times the galaxy has rotated is similar to the age of an earth year problem, no one from Earth really knows how fast or how long a galaxy evolves so they are just estimating based on the best information available and that is commonly agreed upon.


The age of the Universe

Dating the Universe has always been a tricky business with unsatisfying answers. Astronomers now have a better clock, based on radioactive uranium, that puts the age at around 12.5 billion years.

How old is the Universe? This simple and fundamental question has dominated much of astronomy for centuries. Many different techniques have been applied to the problem, including observations of the expansion rate of the Universe, implied by the velocities of distant galaxies, and of the luminosity of the faintest white dwarf stars, which are dying embers of their former selves. But these methods cannot give direct measurements of age — they all rely on assumptions about the nature of the objects being observed. A better approach, radioactive cosmochronometry, relies on measuring the abundance of radioactive thorium found in stars. On page 691 of this issue, Cayrel et al. 1 report the discovery of radioactive uranium in a very old star called CS31082-001, resulting in a major advance for this method. Radioactive cosmochronometry may some day prove to be the anchor for all other estimates for the age of the Universe.

Almost all chemical elements are formed or synthesized by nuclear fusion reactions in the hot and dense interiors of stars or in supernovae. Fusion cycles, such as the conversion of hydrogen to helium and then to carbon, give off energy, which provides the outward pressure needed to stabilize stellar interiors against the inward pull of gravity and the light output of the stars. Progressively heavier nuclei require more energy to form and fusion becomes increasingly difficult. Nuclei of iron are the most tightly bound of all, with nuclei heavier than iron becoming unstable and difficult to create by fusion. So massive stars are fuelled by fusion until they develop an iron core, at which point unbalanced gravitational forces cause the core to implode, sucking in the outer layers until they meet in the middle and rebound, releasing energy — this is a supernova.

The extreme temperature and density of a supernova create huge but short-lived fluxes of neutrons. These fluxes yield extraordinarily neutron-rich nuclei that quickly rearrange themselves for greater stability. This mechanism, called neutron capture, is responsible for the production of the heavy, long-lived radioactive elements, most notably thorium (the half-life of 232 Th is 14.1 billion years (Gyr)) and uranium (the half-life of 238 U is 4.5 Gyr 235 U has a much shorter half-life and so is of less interest here). These elements are especially useful for astronomy because their half-lives are considerable fractions of current estimates of the age of the Universe as determined from other techniques. These estimates currently span the range 9–16 Gyr (for example, see ref. 2).

A high-mass star born early in our Galaxy's history would end its typically short life in a supernova explosion. If that supernova spewed out elements produced by neutron capture into the interstellar medium, some would be radioactive thorium and uranium, and many of those atoms should still be around today, because of their long half-lives. The next generation of stars can sweep up supernova ejecta and we should be able to detect them in their atmospheres by measuring the absorption spectra of the ionized species.

Happily, these elements have been found in stars that reside in the outer regions of the Galaxy — the Galactic halo. Here there are demonstrably old stars that have much less iron (and similar metals) than our relatively young Sun. In some cases, these very metal-poor stars have less than a thousandth of the Solar metal abundance — they have absorbed little supernova ejecta because, when they were born, very few element-donating stars had died. It is difficult to find metal-poor stars, and taking a census of our Galactic halo at moderate photometric and spectroscopic resolutions 3 was a necessary first step.

Ionized species of the rare-earth metals from supernova ejecta are easily detected in metal-poor stars that are enriched in the neutron-capture elements. However, thorium is less prominent, and its abundance in most stars has to be derived from a single transition that is contaminated with other absorbing species 4 . Despite this, thorium has been detected in several metal-poor stars, but in smaller amounts than in the stars in the vicinity of our Solar System, implying that the metal-poor stars are substantially older. Detailed thorium and neutron- capture abundance studies 5,6 suggest that the synthesis of thorium occurred some 14–16 Gyr ago, but the error estimates on this value are frustratingly large, about 4 Gyr.

Cayrel et al.'s studies of the star CS31082-001 could bring us closer to finding out the age of the Universe. This star, serendipitously discovered in a large high-resolution spectroscopy study of very metal-poor stars, has about a thousand times less iron than the Sun. But its neutron-capture elements still exist in high quantities, so their absorptions stand out prominently in this star's spectrum. The authors detected not one but eleven transitions of thorium in CS32081-001. And most importantly, an ionized uranium transition is detected for the first time in a metal-poor star.

The importance of having abundances of both thorium and uranium in a single star cannot be overstated. It is difficult to predict the production of either of these elements by themselves in supernovae and a lively debate 7,8 has centred on how to turn an observed thorium abundance into a reliable age estimate. But it is relatively easy to predict the relative production of thorium to uranium because these elements are separated by only two atomic numbers. And the different decay rates of 232 Th and 238 U ensure that the abundance ratio of these two elements will be a sensitive function of their age. Cayrel et al. 1 propose that the neutron-capture material in the atmosphere of CS31082-001 has an age of 12.5 Gyr with an uncertainty of 3.3 Gyr, a more accurate estimate of the age of the Universe. Further analysis of the whole range of neutron-capture elements in this star will refine this age estimate, narrowing the uncertainty.

We now know of a handful of stars born early in our Galaxy's history that are anomalously enriched in radioactive thorium, and at least one with uranium. We may expect to find more examples of such stars, as our surveys of the Galactic halo with the new generation of very large telescopes is just beginning. With new discoveries, more age estimates will be found, further nailing down the exact age of the Universe.


Age of the Universe? Science versus Young-Earth Creationism

connections between design and age: Most evidences for a design of nature are due to the many fine-tuned properties of nature that must be "just right" for the natural developments that occurred during astronomical evolution. Ironically, when young-earth creationists argue against age-principles (below) they argue against the strongest evidences for an intelligent design of the universe.

This section will help you understand the natural processes that, according to conventional scientific theories, produce astronomical evolution to form stars and galaxies, planets and solar systems. By contrast, most proponents of young-universe theories claim this natural evolution could not occur, and all of them think it did not occur.

Some of the abundant evidence for an old earth and old universe is in AGE OF THE EARTH & UNIVERSE — SCIENTIFIC EVIDENCE which is based on this educational philosophy:
"Our goal is to help you get an accurate understanding, so we've tried to find the best information and arguments claimed as support by both sides, young earth and old earth. And even though the overall result won't be NEUTRAL, we will try to be FAIR by letting representatives of each perspective clearly express their own views and criticize other views, and by treating their views with respect."
Below are two parts of the page (Overviews & Responses, Selected Topics) plus questions about Distant Starlight:

Astronomy — Overviews & Responses
To help you learn quickly and well, here are some carefully selected resources:

The Big Bang Expansion
There is strong evidence indicating that the universe has been expanding for the past 14 billion years.
FAQ from NASA explains why the Big Bang was not an "explosion".
NASA's Universe 101 [also in PDF] &mdash The Big Bang (from Exploratorium) &mdash Three Supports (by Perry Phillips) &mdash news + FAQ + tutorial (from Ned Wright) &mdash Chapters 10-17 in Foundations of Modern Cosmology.
Scientific Confidence: An introductory overview about The Big Bang from All About Science ends with questions that are more skeptical than is justifiable based on evidence and logic. Among scientists who have studied the evidence, almost all (everyone except young-earth creationists whose "scientific" views are based on their interpretations of Genesis, not on scientific evidence-and-logic) have concluded that our universe began with a rapid "big bang" expansion 13.7 billion years ago. Many cosmologists think the expansion was extremely rapid at the beginning, in an inflationary phase, and then slowed down to the current rate of expansion.
More information about cosmological inflation is in the links-page about DESIGN OF THE UNIVERSE, including an explanation of the early shift from high-energy conditions to (relatively) low-energy conditions, which is outlined in Wikipedia's history of the Big Bang (assuming inflation) in a graphical timeline and (with a caution that "all ideas concerning the very early universe are speculative") verbal timeline.

The Life Cycle of Stars
Although there is some variation in lifetimes, for most stars the processes in a life cycle require billions of years. And when we look at different distances away from earth (and thus different times in the past) we can observe many successive generations of stars, each lasting billions of years.
The Life Cycle of Stars - and Birth of Planets (by Deborah Haarsma & Loren Haarsma) &mdash The Life and Death of Stars (from NASA) &mdash Life Cycle of a Star (Protostar & Lifetime - main sequence, equilibrium, after - and HR-Diagram introduction) &mdash How Stars Work (introduction) by HowStuffWorks, including Life & Death and How the Sun Works and more &mdash The Birth of Stars (from Enchanted Learning)

Distant Starlight
This is a major problem for those who propose a young earth-and-universe. Why? If the universe has existed for less than 10 thousand years, how can we see light from distant stars, from stars so far away that light coming from them would take billions of years to reach us? This problem, and proposed solutions, are examined in Distant Starlight - a problem for Young-Earth Creationists.

Determining Age from Observations
&bull Calculating Age (a short series of pages by Exploratorium)
• old-universe claims by TO and Hill Roberts a good overview of current young-universe astronomy by Danny Faulkner young-universe claims by Don DeYoung and Jason Lisle (in chapters from Taking Back Astronomy). The overviews & responses above also include some astronomy, especially in Humphreys (topics 1-3), and TO's Topic-List & Tiscareno (astronomy plus the final topic in page, Star Distances).
There is plenty of evidence for the Big Bang, as described by Hugh Ross & TO (brief) & TalkOrigins (in depth), plus responses to 10 Problems for the Big Bang (Richard Deem) and Astronomical Complexity & The Second Law of Thermodynamics. David Berlinski (OE) wonders what happened before the beginning and Apologetics Press (YE, A B) describes science history and science. John Hartnett and Carl Wieland think disagreements among OE-scientists shows the Big Bang theory is in trouble, but Greg Neyman (A B) explains that this is just how science works.
You can also learn about Distant Starlight (which includes subsections for Light Speed Slowdown [c-decay] & White Hole Cosmology) and more in ASTRONOMY: AGE OF THE UNIVERSE [which is the page you're now reading].

And in the Selected Topics,

Speed of Moon Recession — a problem for OE?
If the moon had moved away for 4.5 billion years at the current rate, it would be much further away.
Speed of Moon Recession — an OE solution?
The arrangement of continents has changed, and this changed the rate of recession, so the "if" isn't correct and neither is the calculation. (TO)
Number of Supernova Remnants — a problem for OE?
In an old universe, we would see more second- and third-generation supernova remnants.
Number of Supernova Remnants — an OE solution?
The YE math is based on wrong premises, and supernovas support OE in several ways. (TO Neyman)


ADDITIONAL RESOURCES
If you want to explore more widely, the Potential Resources Page for Astronomy has links (that are several years old, because the page was assembled in 2006) for resources to supplement those above (the overviews & responses , plus pages about moon recession & supernova remnants and Distant Starlight. The potential resources include these topics:
distant starlight c-decay white hole cosmology apparent age — astronomy Big Bang red shift CMB dark matter — galaxy shapes supernova remnants star evolution black holes faint sun shrinking sun solar neutrinos — NASA & Joshua solar system origin extrasolar planets planet problems comets astronomical cycles planet magnetism space dust water on Mars earth rotation moon recession moon dust moon craters moon-misc — Big Bang & Theism


I.O.U. — Later, other topics (check the Potential Resources Page above for possibilities) will be added to this page.

A DISCLAIMER:
In this page you'll find links to resource-pages expressing a wide range of views, which don't necessarily represent the views of the American Scientific Affiliation. Therefore, linking to a page does not imply an endorsement by ASA. We encourage you to use your own critical thinking to evaluate everything you read.

This website for Whole-Person Education has TWO KINDS OF LINKS:
an ITALICIZED LINK keeps you inside a page, moving you to another part of it, and
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Age of the universe - Astronomy

You explained how 1/H is an inaccurate way of determining the age of the universe. Is there any other quantitative and observational way of more accurately representing the age of the universe?

As we discussed, defining the age of the universe as 1/H is not really correct because it assumes H has been the rate of expansion throughout the universe's history (and thus that the expansion rate has been constant, not accelerating or decelerating).

There are a couple of ways to get good estimates on the age of the universe, but no way to know exactly for sure. For an idea of how hard this is, let's pretend I show you a person and ask you to guess how old she is. It would be somewhat difficult to guess the exact right age, but how would you do it? You would think about how old that person looks compared to other people you know of different ages. Well, we only have one universe, so we can't compare it with other universes so determining the age is very hard! Here are three of the more accurate ways:

1) I mentioned just using 1/H was not a very accurate way of finding the age if we use the current measurement of H only. Remember H measures the rate of expansion so assuming H is constant in time says the universe has always been expanding at the same rate. We know this is not true (we believe the universe is actually accelerating) so to be more accurate we have to come up with a model for what we think the expansion rate has been like. In other words, we have to find H as a function of time, integrate over the history of the universe, and then take the inverse of that to get a more accurate age estimate. We're still doing some guesswork here, because we don't know exactly what H was at every moment in the past (it was hard enough for us to figure out what it is now!) Each model will give a different value for the age, but one of the most popular models gives about 13.8 billion years.

2) Another method is looking at clusters of stars (groups of stars all born at the same time that are at the same distance from us). When stars are in the longest stage of their lives (burning hydrogen) we can put them on a plot of temperature versus luminosity (how bright they are) and we find they all fall in a straight line (we call it the "main sequence"). Based on our knowledge of stars, we know how long each type of star stays on the main sequence. When we observe a cluster of stars, we can see all types of stars filling out the line we call the main sequence. Thus we can see what types of stars have already left the main sequence in old clusters to find an upper limit for the age of the cluster and thus the universe. This method gives ages of 11-13 billion years.

3) There is a special kind of event in some stars' lives called a supernova. A certain kind of supernova occurs when the core of a star becomes a white dwarf (a really compact star near the end of its life) and the star's outer layers bounce off this core and fly into space in a huge explosion. The white dwarf left behind glows at first and then cools as it ages. If we find white dwarves that are really cool, we can estimate how much time must have passed in order for them to get that cool and get a value for the age of the universe. This method gives ages of around 12.7 billion years.

This page was last updated June 27, 2015.

About the Author

Sabrina Stierwalt

Sabrina was a graduate student at Cornell until 2009 when she moved to Los Angeles to become a researcher at Caltech. She now studies galaxy mergers at the University of Virginia and the National Radio Astronomy Observatory in Charlottesville. You can also find her answering science questions in her weekly podcast as Everyday Einstein.


Overviews of Young-Earth Science & Old-Earth Science

We should use all of the information provided for us by God, so usually the reasons for adopting an "age of the universe" view are both scientific (the focus in this page) and theological (the focus in AGE OF THE EARTH & UNIVERSE - THEOLOGICAL PERSPECTIVES).

This page describes high-quality educational resources on the web — with views from a variety of perspectives — that we think you'll find interesting and useful, that will stimulate your thinking and help you explore a wide range of ideas.


Historical Science — Can it be reliable?
We cannot directly observe ancient history, but can we — by a logical analysis of historical evidence (in fields like astronomy, geology, paleontology, evolutionary biology, and archaeology) — reach reliable conclusions about what happened in the past, on the earth and in other parts of the universe? Young-earth creationists ask "Were you there? Did you see it?", and imply that "NO" means "then you can't know much about it." What can we know, and how?

This section is now in its own page — HISTORICAL SCIENCE — which looks at criticisms and responses, and says that " o fficially, ASA does not have a position on historical science" but "unofficially, most members of ASA think the essential foundation of historical science — the logical evaluation of evidence about the past — provides a reliable way to learn about the history of nature."


How old are the earth and universe?
Most scientists think there is overwhelming scientific evidence, from a wide variety of fields, proving (beyond any reasonable doubt) that the earth and universe are very old, with ages of approximately 4.55 and 13.7 billion years, respectively. But proponents of young-earth theories challenge the evaluations that lead to old-earth conclusions.
The rest of this page looks at scientific evidence and logic that can help us answer questions about age. Our goal is to help you get an accurate understanding, so we've tried to find "the best information and arguments that all sides of an issue can claim as support." And even though the overall result won't be NEUTRAL, "we will try to be FAIR by letting representatives of each perspective clearly express their own views and criticize other views, and by treating their views with respect." (quotes from Accurate Understanding and Respectful Attitudes)

Typically, advocates of a young earth claim there are only two basic views of origins: young-earth creation (Christian) and old-earth evolution (atheistic). They define all old-earth views as "evolutionary" and imply that an old-earth view cannot be authentically Christian. They ignore the important differences between three questions (when, how, who) and use "when" to define the answer to all three. But the actual situation is not this simple, as you can see in THREE VIEWS OF CREATION.

For all age-questions, we encourage you to carefully examine the scientific evidence-and-logic.
But it's more important to ask, "Is young-earth belief an essential part of Christian theology?"
and ask yourself whether it seems wise to insist that "if the earth is not young, the Bible is not true."


You can jump to Selected Topics or begin with these Overviews & Responses:

Old-Earth Science Overviews (geology & more)
• Craig Rusbult explains the logical principle of Multiple Independent Confirmations — regarding what we can conclude from the fact that "abundant evidence from a wide range of fields. indicates that the earth and universe are billions of years old" &mdash and summarizes Scientific Evidence for an Old Earth from a wide range of fields.
• Deborah Haarsma & Loren Haarsma briefly summarize Geological Evidence [before 1840] for an Old Earth.
• Hill Roberts — Evidences (*) That Have Led Many Scientists to Accept An Ancient Date for Creation of the Earth and Universe. (* from geology, radiometric dating, plate tectonics, astronomy, and the Bible)
• David Leveson explains how scientists determine the relative ages and absolute ages of rock formations.
• Mark Isaak asks 20 tough questions about Producing the Geological Record in a Global Flood.
• Answers In Creation offers a free Online Geology Curriculum for homeschoolers, or anyone who wants to learn.
• Greg Neyman, from Answers in Creation, examines stratigraphy (science of geological layers) in the western United States, especially the Grand Canyon, and EarthHistory evaluates young-earth theories in the conclusion of a 5-part series about the Grand Canyon.
• Dan Wonderly — The Date of Creation: Bible-Compatible Evidences for Great Age and other resources from Wonderly.

Young-Earth Science Overviews (geology & more)
• John Morris proposes major geological changes during Creation Week and Noah's Flood.
• Tas Walker offers a 12-page series about Biblical Geology.
• Arthur Chadwick outlines a Creation/Flood Model.
• claims for young-earth evidence (from geology, radiometric dating, astronomy. ) by Russell Humphreys and Carl Wieland and Jonathan Sarfati.
• a summary (by Ashby Camp) of ideas in Faith, Form and Time (a book by Kurt Wise, a prominent young-earth scientist).
• and within the community of young-earth creation scientists, debates about theories and approaches.

Old-Earth Responses (geology & more)
Advocates of young-earth flood geology often point to a geological feature caused by a fast-acting catastrophic event (a flood, volcano. ) and imply that this proves old-earth geology is wrong because it insists that ALL geological features were produced by slow-acting uniformitarian processes. But modern conventional geological science, which is accepted by almost all geologists, is a "hybrid combination" proposing that slow uniformitarian processes produced most features, but fast catastrophic events produced some features, as explained by Mark Isaak and Greg Neyman.
Two young-earth models (for plate tectonics & radiometric dating) are evaluated by Deborah Haarsma & Loren Haarsma and Greg Neyman examines catastrophic plate tectonics and provides links (1 at start, 7 at end) where you can learn more. Twenty young-earth books are reviewed by Greg Neyman & others who explain why "the scientific arguments [for a young earth & young universe] are completely void of any credible evidence."
Hundreds of questions — about the when and how of origins, in areas of geology, physics, astronomy, biology, and beyond — were examined by Mark Isaak (for Talk Origins) and then Greg Neyman (for Answers in Creation),who give brief responses ( * ) that are labeled "TO" and "AiC" in the topics-table below. In a similar way, except in one big page instead of many small ones, Matthew Tiscareno and Brent Dalrymple present old-earth evidence while responding to a variety of young-earth claims and, for a smaller range of questions, Chris Stassen and a collection of small pages assembled, by Craig Rusbult, from the topics-pages below.

Young-Earth Responses (geology & more)
One response is to acknowledge the weakness of current young-earth science, but hope it will improve in the future and will become more satisfactory. < But most scientists think this optimism is not justified, since the abundant evidence for an old earth (and old universe) occurs in so many different areas, covering a wide range of phenomena, and is strong in each area. >Another response is to claim that their own logical analysis of the evidence is better than the conventional analysis:
Tas Walker responds to old-earth arguments and there is a 3-part series (OE YE OE) about The Problems of Flood Geology by Mark Isaak (OE) & Jonathan Sarfati (YE) & Brad Henke (OE), and a comprehensive page about The Fossil Record by Sean Pitman. * For counter-responses to the responses from TalkOrigins, CreationWiki summarizes many young-earth claims.


Radiometric Dating — Overviews & Responses
• Principles and applications are explained by the Haarsmas and Roger Wiens (briefly & in detail) and Jonathon Woolf & Brent Dalrymple & Hill Roberts. The reliability of radiometric dating is challenged in AIG's Answer Book (Ham, Sarfati & Wieland) and by Clyde Webster and in Arthur Chadwick's 56-part FAQ but Brent Dalrymple responds to these criticisms.
• The results of RATE (Radioactivity and the Age of The Earth), a young-earth research project by ICR, are described in book-outlines of Thousands not Billions (popular level) and Radioisotopes and the Age of the Earth (technical level) a dialogue in ASA's journal begins with Assessing the RATE Project by Randy Isaac (June 2007) followed (in March 2008) by response & replies from RATE plus Randy Isaac and Kirk Bertsche expanded responses from RATE authors, Isaac, and Bertsche, plus Gary Loechelt and others, are in RATE AND RADIOMETRIC DATING. / The claims of RATE are also criticized by Stephen Meyers & Greg Neyman and others.


Astronomy — Overviews & Responses
To help you learn quickly and well, here are some carefully selected resources:
• explanations of the Big Bang Expansion: a brief overview and Cosmology 101 (a series from NASA) and Three Evidences (by Perry Phillips) and news + FAQ + tutorial (from Ned Wright).
old-universe claims by TO and Hill Roberts a good overview of current young-universe astronomy by Danny Faulkner young-universe claims by Don DeYoung and Jonathan Sarfati (with science plus Galileo). The overviews & responses above also include some astronomy, especially in Humphreys (topics 1-3), and TO's Topic-List & Tiscareno (astronomy plus the final topic in page, Star Distances).

There is plenty of evidence for the Big Bang, as described in the above (in the overview, Cosmo 101, Phillips, Wright) and by Hugh Ross & TO (brief) & TalkOrigins (in depth), plus responses to 10 Problems for the Big Bang (Richard Deem) and Complexity & The Second Law (Craig Rusbult). David Berlinski (OE) wonders what happened before the beginning and Apologetics Press (YE, A B) describes science history and science. John Hartnett and Carl Wieland think disagreements among OE-scientists shows the Big Bang theory is in trouble, but Greg Neyman (A B) explains that this is just how science works. Astronomy (about Distant Starlight, Big Bang, and Solar System) is in Chapters 1-3 of an excellent book (available online) by Robert Newman & Perry Phillips, Genesis One and the Origin of the Earth (2nd Edition, 2007).
You can also learn about Distant Starlight (plus Light Speed Slowdown & White Hole Cosmology) and more in ASTRONOMY &mdash AGE OF THE UNIVERSE.


Scientific Methods and Logical Evaluations
This page begins by asking, Can we use historical science to get reliable information about the history of nature?
Usually, advocates of a young earth say NO. Frank Sherwin, a young-earth scientist, seems to disagree when he explains why scientists should Follow the Evidence but John Morris thinks scientists cannot study the past with confidence so Biblical interpretation (not historical science) is the most reliable way to know the history of nature. Ken Ham agrees he thinks the old-earth conclusions of conventional science are not due to scientific evidence-and-logic, they are caused by scientists looking through a sinful secular lens (not a Biblical lens) with old-earth presuppositions he thinks we should return to Biblical authority and should not "start outside the Bible to (re)interpret the Words of Scripture" but (as explained by Craig Rusbult) he doesn't follow his own advice when he asks, does the earth rotate and orbit?
To gather information about their young-earth (YE) views of science, ask a YE believer, "Is there any scientific evidence that would convince you the earth is old?" If they answer yes, ask "then why do you harshly criticize the theology (and sometimes the faith and character) of the many Christians (your brothers and sisters in Christ) who have logically and prayerfully examined the evidence, and it has convinced them that the scientific support for an old earth is extremely strong?" If they say no, ask "should a scientist reach a conclusion before examining the evidence?"
Greg Neyman describes the conclusion first approach of YE "scientists" and the tendency of young-earth believers to avoid old-earth evidence, and the fact that YE websites don't link to pages with OE evidence-and-logic so it won't be seen by their YE followers and Glenn Morton explains how, when he was a YE believer, his Morton's [YE] Demon prevented him from seeing any non-YE evidence.
How can we wisely use information from THE TWO BOOKS OF GOD in Scripture and Nature?


Selected Topics
The table below shows age-claims (•) and responses from two perspectives, young earth (YE) and old earth (OE). If you want to study these topics (and many others) in more depth, you can explore four pages — for NOAH'S FLOOD, GEOLOGY, RADIOMETRIC DATING, and ASTRONOMY — that contain plenty of educational resources.

For a variety of reasons — personal and interpersonal, spiritual and scientific — it's important to ask, "Is young-earth belief an essential part of Christian theology?"

note: Information about size (such as "8 k") is for the main part of a page, not including end-references the "AiC" and "TO" pages are brief, usually about 1 k, as explained above.

How were fossils formed, and what can they tell us about age of the earth?
Each view should be criticized for what it is, not what it isn't. A central educational goal of this website is to describe all views accurately, and not allow any distorted "strawman" caricatures built by opponents of a view. In the pages below, it's clear that OEs propose a combination of slow-acting uniform process and fast-acting catastrophic events, as explained earlier. But YEs often imply that OEs think ALL features were formed slowly by an accumulation of small events, with NO features formed quickly by relatively large events. When you read, think carefully with alert awareness, and don't allow any inaccurate strawmen in your thinking.
Basic Fossil Principles are explained by Don Lindsay (OE, A B C D) and John Morris (YE, A B).
Rapid Rocks: Does OE claim that ALL rocks and fossils are formed slowly? Consider some YE claims (by John Morris, AIG, and Tas Walker) and OE responses (by Greg Neyman): YE OE - YE - YE OE. When you're evaluating the relevance of analogies, think about similarities and also differences between the analogy-situation and actual-situation. For example, don't just ask "Can a rock form quickly?", also ask "Could this rock form quickly?" And the problem for YE is not speed, it's geological context.
YEs claim their position is supported by mass burials (YE OE) and polystrate (upright, in situ) fossils: YE OE. YEs claim that SOME fossils formed quickly, and OEs agree but they disagree with a YE implication that ALL formed quickly (A B) and they wonder about numbers (OE YE). Here are pairs about moulting (YE OE) and birth (YE OE), a dino (YE OE) and whales (YE OE), plus contorted fossils [OE] and a "how fast" overview [YE].

Fossil Patterns in Geology — YE solutions?
Tas Walker introduces basic principles (7 k) and Jim Gibson analyzes fossil patterns (48 k).

Fossil Patterns in Geology — a problem for YE?
Do fossil patterns exist, and are they explained by ecological zonation or hydrology or ability to escape or a combination of these factors? (TO) Glenn Morton describes some fossil patterns. (plus Patterns of Small Fossils)

Volcano Pollution during Flood — YE solution?

[so far, I haven't found any YE responses for this]

Volcano Pollution during Flood — problem for YE?
Glenn Morton describes the resulting sulfuric acid (9 k) and carbon dioxide (4 k) and you can read a pollution paper (11 k) rejected by a young-earth journal.

Extrapolation of Rates
Matthew Tiscareno explains why many young-earth claims — based on "measuring rates of various Earth processes, then attempting to extrapolate them backwards for millions of years. to show that the process in question would [with an old earth] build up to absurdity" — are not scientifically valid because they ignore or underestimate opposing processes (that lead to long-term balance) or changes in rate. The following young-earth claims are from the overviews above.

Helium in Air and Rocks — problem for OE?
Jonathan Sarfati outlines two helium-arguments by explaining why, if the earth is old, we should observe more helium in the atmosphere (from which it escapes slowly) and less helium in zircon-rocks (from which it escapes quickly). Russell Humphreys explains the details of his rock-argument that is based on the diffusion of helium out of zircons.


We hope you'll carefully examine the questions above by clicking the links and reading the pages,
and (if you want) you can expand your studies of these age-questions, and others,
by using the abundant educational resources above and area-pages below.

If you want to learn more
about age-science questions,
you can explore these areas:


What am I missing relating to the age of the universe?

Firstly, I'm hoping I've posted this in the right section - if not please let me know which one would be better.

I was mulling over the age of the universe while imaging the other night and drinking a glass of wine. It is accepted the age of the universe is about 13.8B years and that it started with the Big Bang, which says everything started at a point source and expanded rapidly outwards.

If this is the case, and the detectable edge of the known universe is 13.8B years, how can the age of the universe be the same? My reasoning, since nothing can travel faster than the speed of light, and if what is now the edge of the universe was once at the point source at the time of the big Bang, then it would have taken finite time for the edge of the known universe to get where it is now. The minimum amount of time would be 13.8B years (as nothing can travel fast than the speed of light), so the minimum age of the universe must be at least 2 x 13.8B years, and invariable much older since the edge of the known universe is not traveling outwards at the speed of light.

Clearly, my reasoning must be wrong, but I struggling to see why. Can anyone help?

#2 Joe1950

The actual size of the known or visible universe is about 93 billion light years (diameter). That is much larger than the nearly 28 billion calculated directly from its age.

The reason is that as the matter in the universe has been expanding outward with time from the Big Bang, so has the space of the universe itself been expanding. Or, to put it another way, space itself has also been expanding along with the contents of the universe, thus the total is much larger than the expected 28 billion LY.

Einsteins Special Theory Of Relativity limits anything with mass (or information) within the universe to travel less than the speed of light! But, it does not constrain space itself from expanding faster than light!

The reason the known or visible universe is 93 billion LY in diameter, is that the space beyond that distance is traveling faster than light, from our perspective. That expansion is allowed under Special Relativity, and traveling faster than light it cannot be seen from earth regardless of the instruments used.

Hope this helps. I can’t say I totally understand it, but it is the conventional knowledge.

#3 barbarosa

I think that you have the right question, more or less (more or less seems the rule in cosmology).

But this excerpt from Wiki gives us an idea of how difficult it is to get the question and answer in to ordinary terms, that is a distance and a time from one place to another or from one edge to the other.

The proper distance—the distance as would be measured at a specific time, including the present—between Earth and the edge of the observable universe is 46 billion light-years[50] (14 billion parsecs),[51] making the diameter of the observable universe about 93 billion light-years (28 billion parsecs).[50] The distance the light from the edge of the observable universe has traveled is very close to the age of the Universe times the speed of light, 13.8 billion light-years (4.2×109 pc), but this does not represent the distance at any given time because the edge of the observable universe and the Earth have since moved further apart

Because I think about things in an ordinary Newtonian way, the article that was quoted and along with the >100 citations and cross references, just doesn't tempt me to into thinking that I will understand it.

Edited by barbarosa, 04 February 2020 - 03:34 PM.

#4 garyhawkins

I thought I was asking a dumb question but it seems I was not . Pity, I forgot to look at Wikipedia, it's usually my go to source for information. Thanks for both your replies, this makes much more sense.

#5 Gipht

Here is another article that talks about what might be outside the "observable" universe: https://dailygalaxy. eekend-feature/ and the answer is of course, we don't know.

#6 guidoforrier

as far as i know stars , gases and all what you can find in the universe will not travel at light speed :otherwise everything wil be energy .

i also have my doubts about the Big Bang , expanding universe , age of the universe etc. all these theories come from Georges Henri Joseph Édouard Lemaître , a Jesuit trained Belgian Catholic priest . his religion told him that God created the universe an that was de moment of the beginning ,the so called "alpha" and everything comes to an end ( "omega") . so everything started with a singularity and will end . i do not know where or when . other religions or philosophies see no beginning or end .

what is this singularity ? somethings abstract to explain something you can not explain ?

what was before the big bang ? or is it simply silly to speak about a beginning and an end . what is the out border of space ? what is behind this border . a border needs at least 2 regions .my opinion is that we can not talk about these matters and that we should be silent .

Edwin Hubble concluded that galaxies are drifting apart in 1929 from analysis of galactic redshifts. But he also denied some findings of an assistant and broke his career . ( i can not find the name of this assistant )

#7 DaveC2042

I think that you have the right question, more or less (more or less seems the rule in cosmology).

But this excerpt from Wiki gives us an idea of how difficult it is to get the question and answer in to ordinary terms, that is a distance and a time from one place to another or from one edge to the other.

The proper distance—the distance as would be measured at a specific time, including the present—between Earth and the edge of the observable universe is 46 billion light-years[50] (14 billion parsecs),[51] making the diameter of the observable universe about 93 billion light-years (28 billion parsecs).[50] The distance the light from the edge of the observable universe has traveled is very close to the age of the Universe times the speed of light, 13.8 billion light-years (4.2×109 pc), but this does not represent the distance at any given time because the edge of the observable universe and the Earth have since moved further apart

Because I think about things in an ordinary Newtonian way, the article that was quoted and along with the >100 citations and cross references, just doesn't tempt me to into thinking that I will understand it.

But good luck to you.

It's even worse than that. Because the expansion of the universe isn't constant you wind up with a really messy integral taking the change in expansion speed into account.

And even worse than that. We don't really know for sure how that expansion changes - it's 'theory-dependent'. So you have a different integral depending on what your view of things like inflation and dark energy are.

The mathematical details are beyond me.

Edited by DaveC2042, 04 February 2020 - 05:13 PM.

#8 garyhawkins

But the same Wiki piece says, " The Big Bang theory is the prevailing cosmological description of the development of the Universe. Under this theory, space and time emerged together 13.799±0.021 billion years ago[2] and the energy and matter initially present have become less dense as the Universe expanded."

Which goes back to my original question, if the Big Bang emanated from a point source, the age of the universe should not equal the distance to the edge of the known universe in light years, as that material had to travel there in the first place. So it seems like we have a contradiction?

I think that you have the right question, more or less (more or less seems the rule in cosmology).

But this excerpt from Wiki gives us an idea of how difficult it is to get the question and answer in to ordinary terms, that is a distance and a time from one place to another or from one edge to the other.

The proper distance—the distance as would be measured at a specific time, including the present—between Earth and the edge of the observable universe is 46 billion light-years[50] (14 billion parsecs),[51] making the diameter of the observable universe about 93 billion light-years (28 billion parsecs).[50] The distance the light from the edge of the observable universe has traveled is very close to the age of the Universe times the speed of light, 13.8 billion light-years (4.2×109 pc), but this does not represent the distance at any given time because the edge of the observable universe and the Earth have since moved further apart

Because I think about things in an ordinary Newtonian way, the article that was quoted and along with the >100 citations and cross references, just doesn't tempt me to into thinking that I will understand it.

But good luck to you.

#9 Keith Rivich

But the same Wiki piece says, " The Big Bang theory is the prevailing cosmological description of the development of the Universe. Under this theory, space and time emerged together 13.799±0.021 billion years ago[2] and the energy and matter initially present have become less dense as the Universe expanded."

Which goes back to my original question, if the Big Bang emanated from a point source, the age of the universe should not equal the distance to the edge of the known universe in light years, as that material had to travel there in the first place. So it seems like we have a contradiction?

Not an expert by any means but I believe the contradiction is addressed by Inflationary Theory. Early on the universe went through rapid inflation and the "edges" are expanding at faster then c velocities thus the universe can be younger then its diameter.

#10 garyhawkins

Thanks Keith, I'll do a little bot of research.

Not an expert by any means but I believe the contradiction is addressed by Inflationary Theory. Early on the universe went through rapid inflation and the "edges" are expanding at faster then c velocities thus the universe can be younger then its diameter.

#11 RaulTheRat

There's a couple of things to point out here.

First, nothing can move _through space_ faster than light. That doesn't mean two things embedded in expanding space (eg two galaxies) can't be moving away from each other at superluminal speeds. Indeed most of the universe is expanding away from us faster than the speed of light. Remember, the big bang wasn't an explosion _in_ space, it was (and possibly is because there's no certainty that it finished) an expansion _of_ space. Nothing is flying away from the "centre", and there is no "centre", the big bang happened everywhere, and the stuff that is moving apart because of the expansion is moving apart much as dots drawn on a balloon move apart when you blow it up - the dots aren't moving on the rubber surface, the surface itself is changing. That analogy is useful but it's also useful to remember that the balloon is expanding into 3d space around it, space is not expanding into anything that's outside.

We can indeed see things that are today moving away faster than light speed as well, it's just that unless the expansion changes, we will never be able to see what's happening at those things now. We see photons that were emitted by them long ago when they were moving away from us at less than the speed of light, but we will never be able to see the photons they are emitting today.

Take for example a galaxy that had a supernova in it some billions of years ago when it was moving away from us at some significant fraction of the speed of light, but not above it. Now, it is moving away faster than light speed, but we can receive the light emitted by the supernova, even though that light has to travel further than what the distance to that galaxy was at the time of the supernova (because as the light makes its way to us, the space keeps expanding), and the galaxy from which it was emitted has moved further away. We can say that the supernova happened for example 10B LY away, and that the galaxy is now for example 30B LY away (totally concocted numbers, but you get the idea).

The furthest things we can see are now about 46 billion light years away. Because they are the furthest things we can see, we see them as they were about 13.8 billion years ago, when they emitted the light we see before they crossed our casual horizon and they are now so far away that no signal could ever reach us from them today (or vice versa).

We can also in fact see some things that were moving away faster than light when they happened. This is because in the earlier matter dominated period, the expansion slowed down, allowing photons that initially started out moving away from us (even though they were moving through space at exactly C) to enter regions that were moving away from us at less than C.

Edited by RaulTheRat, 05 February 2020 - 03:58 PM.

#12 garyhawkins

Thanks for your feedback - I think I can see where this is going. Funny, I just had a very similar conversation with my brother - he's a bit of an astronomy buff as well.

There's a couple of things to point out here.

First, nothing can move _through space_ faster than light. That doesn't mean two things embedded in expanding space (eg two galaxies) can't be moving away from each other at superluminal speeds. Indeed most of the universe is expanding away from us faster than the speed of light. Remember, the big bang wasn't an explosion _in_ space, it was (and possibly is because there's no certainty that it finished) an expansion _of_ space. Nothing is flying away from the "centre", and there is no "centre", the big bang happened everywhere, and the stuff that is moving apart because of the expansion is moving apart much as dots drawn on a balloon move apart when you blow it up - the dots aren't moving on the rubber surface, the surface itself is changing. That analogy is useful but it's also useful to remember that the balloon is expanding into 3d space around it, space is not expanding into anything that's outside.

We can indeed see things that are today moving away faster than light speed as well, it's just that unless the expansion changes, we will never be able to see what's happening at those things now. We see photons that were emitted by them long ago when they were moving away from us at less than the speed of light, but we will never be able to see the photons they are emitting today.

Take for example a galaxy that had a supernova in it some billions of years ago when it was moving away from us at some significant fraction of the speed of light, but not above it. Now, it is moving away faster than light speed, but we can receive the light emitted by the supernova, even though that light has to travel further than what the distance to that galaxy was at the time of the supernova (because as the light makes its way to us, the space keeps expanding), and the galaxy from which it was emitted has moved further away. We can say that the supernova happened for example 10B LY away, and that the galaxy is now for example 30B LY away (totally concocted numbers, but you get the idea).

The furthest things we can see are now about 46 billion light years away. Because they are the furthest things we can see, we see them as they were about 13.8 billion years ago, when they emitted the light we see before they crossed our casual horizon and they are now so far away that no signal could ever reach us from them today (or vice versa).

We can also in fact see some things that were moving away faster than light when they happened. This is because in the earlier matter dominated period, the expansion slowed down, allowing photons that initially started out moving away from us (even though they were moving through space at exactly C) to enter regions that were moving away from us at less than C.


Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2003 February 17
Universe Age from Microwave Background
Credit: WMAP Science Team, NASA

Explanation: The above sky map tells us the universe is 13.7 billion years old -- but how? At first look, one only sees the microwave glow of gas from our Milky Way Galaxy, coded red, and a spotty pattern of microwaves emitted from the early universe, coded in gray. The gray cosmic microwave background is light that used to bounce around randomly but came directly to us when the expanding universe became cool enough for nearly transparent atoms to form. A close inspection of the spots reveals a slightly preferred angular distance between them. One expects such a pattern to be generated by sound emanating from slightly over-dense regions of the early universe. Sound waves will take time to generate such a pattern, and the present age of the universe can then be directly extrapolated. The above universe age is estimated to be accurate to better than 0.2 billion years. The above map was taken by the WMAP satellite orbiting the Sun at the L2 point, just outside the orbit of the Earth.


Blog #17- Size and Age of the Universe

One of the most controversial questions in astronomy is if the universe still expanding. Astronomers have studied this for centuries and have concluded a faster rate of expansion in today’s universe than after the Big Bang. The Hubble Space Telescope found the rate of expansion of today is 9 percent off from the rate of the early universe. To measure it, researchers look at Cepheid variables. Since more distant stars appear dimmer, they can use the timing of the star’s cycle and how bright they appear to measure the distance. Finding these measurements can reveal the distances to farther galaxies. Astronomers are still trying to put the pieces together and come up with a better model to our universe.

Although we went through this objective really quick in class, we talked about how astronomers know that the universe is expanding and how they determine the age of the universe. Our professor went over notes about the universe. First, we went over energy release and how quasars emit in all part of the electromagnetic spectrum. Many shine with the light of 100 galaxies. Some nearby galaxies show jets of radiating gas. The jets emerge from the galactic nucleus (a black hole). When a lot of matter falls into the black hole, it becomes active. The theory of an initial explosion predicts uniform microwave emission from space. Hubble’s law suggests that the galaxies in the universe are spreading over time.

The article mirrors what every astronomers is trying to figure out. I learned a lot about our universe and how it all came about. One thing that got stuck to my head is as the universe expands the wavelength of light stretches. Another concept I learned is if gravity is too weak, the universe expands forever. Similarly, if gravity is strong, the universe will eventually collapse. It was too much to take in just because there is so much to talk about in such too little time. My astronomy class really made me open my eyes to a whole new world that I wouldn’t be interested if I did not take this course.


The Nature of Astronomy

Astronomy is defined as the study of the objects that lie beyond our planet Earth and the processes by which these objects interact with one another. We will see, though, that it is much more. It is also humanity’s attempt to organize what we learn into a clear history of the universe, from the instant of its birth in the Big Bang to the present moment. Throughout this book, we emphasize that science is a progress report—one that changes constantly as new techniques and instruments allow us to probe the universe more deeply.

In considering the history of the universe, we will see again and again that the cosmos evolves it changes in profound ways over long periods of time. For example, the universe made the carbon, the calcium, and the oxygen necessary to construct something as interesting and complicated as you. Today, many billions of years later, the universe has evolved into a more hospitable place for life. Tracing the evolutionary processes that continue to shape the universe is one of the most important (and satisfying) parts of modern astronomy.


New View of Nature’s Oldest Light Adds Twist to Debate Over Universe’s Age

From a mountain high in Chile’s Atacama Desert, astronomers with the National Science Foundation’s Atacama Cosmology Telescope (ACT) have taken a fresh look at the oldest light in the universe. Their new observations plus a bit of cosmic geometry suggest that the universe is 13.77 billion years old, give or take 40 million years.

The new estimate matches the one provided by the standard model of the universe and measurements of the same light made by the Planck satellite. This adds a fresh twist to an ongoing debate in the astrophysics community, says Simone Aiola, first author of one of two new preliminary papers on the findings posted to arXiv, a preprint server, and in review at the Journal of Cosmology and Astroparticle Physics. The second paper’s lead author is Steve Choi, Cornell Presidential Postdoctoral Fellow and researcher at the Cornell Center for Astrophysics and Planetary Science in the College of Arts & Sciences.

In 2019, a research team measuring the movements of galaxies calculated that the universe is hundreds of millions of years younger than the Planck team predicted. That discrepancy suggested that a new model for the universe might be needed and sparked concerns that one of the sets of measurements might be incorrect.

“Now we’ve come up with an answer where Planck and ACT agree,” says Aiola, a researcher at the Flatiron Institute’s Center for Computational Astrophysics. “It speaks to the fact that these difficult measurements are reliable.”

The age of the universe also reveals how fast the cosmos is expanding, a number quantified by the Hubble constant. The ACT measurements suggest a Hubble constant of 67.6 kilometers per second per megaparsec. That means an object 1 megaparsec (around 3.26 million light-years) from Earth is moving away from us at 67.6 kilometers per second due to the expansion of the universe. This result agrees almost exactly with the previous estimate of 67.4 kilometers per second per megaparsec by the Planck satellite team, but it’s slower than the 74 kilometers per second per megaparsec inferred from the measurements of galaxies.

“I didn’t have a particular preference for any specific value — it was going to be interesting one way or another,” says Choi. “We find an expansion rate that is right on the estimate by the Planck satellite team. This gives us more confidence in measurements of the universe’s oldest light.”

But the discrepancy between the measurements suggests that either there is something missing in our cosmological model or there is something wrong with the measurements, says Michael Niemack, co-author on the two preliminary papers. While several local universe measurements find a consistently higher Hubble constant, this is the first time that two independent cosmic microwave background (CMB) measurements found consistently lower Hubble constants. (The CMB marks a time 380,000 years after the universe’s birth when protons and electrons joined to form the first atoms. Before that time, the cosmos was opaque to light.)

“The growing tension between these distant versus local measurements of the Hubble constant suggests that we may be on the verge of a new discovery in cosmology that could change our understanding of how the Universe works. It also highlights the importance of improving our measurements of the CMB with ACT as well as the future Simons Observatory and CCAT-prime projects that we are now building,” says Niemack, associate professor of physics and astronomy.

Like the Planck satellite, ACT peers at the CMB, the afterglow of the Big Bang.

If scientists can estimate how far light from the CMB traveled to reach Earth, they can calculate the universe’s age. That’s easier said than done, though. Judging cosmic distances from Earth is hard. So instead, scientists measure the angle in the sky between two distant objects, with Earth and the two objects forming a cosmic triangle. If scientists also know the physical separation between those objects, they can use high school geometry to estimate the distance of the objects from Earth.

Subtle variations in the CMB’s glow offer anchor points to form the other two vertices of the triangle. Those variations in temperature and polarization resulted from quantum fluctuations in the early universe that got amplified by the expanding universe into regions of varying density. (The denser patches would go on to form galaxy clusters.) Scientists have a strong enough understanding of the universe’s early years to know that these variations in the CMB should typically be spaced out every billion light-years for temperature and half that for polarization. (For scale, our Milky Way galaxy is about 200,000 light-years in diameter.)

ACT measured the CMB fluctuations with unprecedented resolution, taking a closer look at the polarization of the light. “The Planck satellite measured the same light, but by measuring its polarization in higher fidelity, the new picture from ACT reveals more of the oldest patterns we’ve ever seen,” says Suzanne Staggs, ACT’s principal investigator, at Princeton University.

As ACT continues making observations, astronomers will have an even clearer picture of the CMB and a more exact idea of how long ago the cosmos began. The ACT team will also scour those observations for signs of physics that doesn’t fit the standard cosmological model. Such strange physics could resolve the disagreement between the predictions of the age and expansion rate of the universe arising from the measurements of the CMB and the motions of galaxies.

The ACT team is an international collaboration, with scientists from 41 institutions in seven countries, in which Cornell University plays an essential role. Cornell researchers helped develop the ACT optics, detector arrays, survey strategy, software infrastructure, and data analysis tools. Niemack led the development of the Advanced ACTPol detector arrays and serves on the ACT guiding board. ACT is supported by the National Science Foundation and contributions from member institutions.


Watch the video: JOURNEY TO THE EDGE OF THE observable UNIVERSE w. Alec Baldwin 1080p (January 2023).