Age of universe Definition and 37 Threads

Hi, I'm aware of the measured recession of the galaxies in our universe and the universe expansion itself cannot be understood as an "ordinary" velocity/speed (for instance in the FRW solutions of Einstein's equations). Can you kindly help me clarify this topic ? Thank you.

The article https://phys.org/news/2023-07-age-universe-billion-years-previously.html#:~:text=42-,New%20research%20puts%20age%20of%20universe%20at%2026.7%20billion%20years,as%20old%20as%20previously%20believed&text=Our%20universe%20could%20be%20twice,%22impossible%20early%20galaxy%20problem.%22...

do we know for a fact that the gravitational constant has always been the same since the dawn of the universe? I feel like gravitational forces should slowly be decreasing as the universe ages (meaning that assuming mass of Earth doesn't change, we should weigh a bit less in a billion years)...

I was thinking about the age of the universe which is said to be 13.8 billion years approximately. I read that this is derived from two sources , calculating the life of the oldest stars in the observable universe and from extrapolating backwards the distance which is radius from Earth to all...

Does knowing the age of the universe (13.8 billion? ) say anything about size of the universe (besides the observable size)?

Homework Statement I'm using python to calculate the age of the universe, by working out the distmodulus for a set of galaxys (using the V and I bands) then working out the distance in parsecs and then hubbles constant etc... I keep getting values that are 10s of magnitudes out which I assume...

I'm trying to reconcile the age and size of the universe. The size of the universe is more than twice the distance light can travel in the time it has existed. Does this mean that the universe is expanding faster than the speed of light or that it did initially and has slowed down since? I...

Hello, I've a problem. I need to find the age of universe in normalized Planck units. In my case, I'm using Planck mass = 1 and: ##H = 1.18 × 10^{-61} \times t_P^{- 1}## With these values, how can I find the age of the universe? Thanks!

Forgive my ignorance?.. If we can see 13.8-ish billion light years away how can the universe be the same age? Matter cannot travel at the speed of light, so how are we as far away (in light years) as the universe is old?

Forgive my ignorance?.. If we can see 13.8-ish billion light years away how can the universe be the same age? Matter cannot travel at the speed of light, so how are we as far away (in light years) as the universe is old?

The Size and Age of Our Universe If the universe is 14 billion years old, (roughly) then we can only see out in any direction for 14 billion light years. Thus any stars beyond 14 billion light years are invisible to us because their light hasn’t had time to reach us. If we cannot find an edge...

I'm a retired geologist ... Know little about cosmology or quantum physics so will defer to others. Please excuse my rambling question. Something has always 'made me wonder' about the potential fate of the Universe. Almost all models predict either an infinite Universe or a Universe that...

I understand that it's possible to calculate the age of terrestial planets through radioactive dating their soil. However, the gas planets present a different challenge since we cannot currently land on them. Any ideas on how to calculate their ages in a different manner?

Please help me understand this. The age of the universe is given as being about 13.8 billion years. The size of the universe is estimated to be 93 billion light years ( https://en.m.wikipedia.org/wiki/Universe) Since the oldest light to reach us comes from 13.8 light years away, why do we...

After a recent conversation, I was trying to determine if there is an online authoritative definition for the age of the universe. The Wiki article states "the International Astronomical Union presently use 'age of the universe' to mean the duration of the Lambda-CDM expansion", but the...

Acc. to general relativity time runs slowly near a massive body.So, i have a question bothering me from some time that if time for every body/object in universe runs at a different rate then how can we determine the age of universe i.e. 13.72 billion years. Near a black hole as time runs...

The estimated age of the universe is often stated to be about 13.7 billion years. But I've never seen any qualifiers on that age. We know that time passes slower the greater the gravity field you're in. Even the difference in gravity between the Earth's surface and orbit is enough to cause...

Hi, The Universe in 14 billion years old. Is that then: 14,000,000,000,000 or 14 million million as in 1.4x1013 years old or 14,000,000,000 or 14 thousand million as in 1.4x1010 years old (I know a billionaire has a thousand million 1,000,000,000) Thanks,

I've pondered a hypothetical problem Take as time perspective "A" as being relative time dilation of Earth Time dilation "B" being half of "A" slower due to relativistic effects. assuming both "A" and "B" were both formed at the same time say 5 billion years ago. If you were to...

Quantum Confusion -- "Does not exist until it's observed" and age of universe Hi. I ran across this: http://physics.jamesbaugh.com/quanta.html QUOTE: "It is a problem of assuming values of properties are "out there" independently of the acts by which the values are determined. The...

hello, I'm wondering how to calculate, even approximately for the relatively mature universe, what the CBR wavelength was as a function of age of the universe. I get that the CBR began during recombination, though have read different values for the black body temperature at that...

People always say the Universe is 14 billions year old. But what does that mean? What is the time of the Universe relative to?

Hi, I am currently reading Liddles Introduction to Modern Cosmology (2nd Ed) and having trouble with problem 8.4, about the age of the universe with a cosmological constant. The question asks to derive the formula for the age by first writing the Fridemann equation in such a model as...

I was wondering if, immediately following the expansion of the universe there might have been objects of matter with immense gravity like that of a black hole. For the observer on such an object that still exists, what would the age of the universe be? You could substitue this with an object...

Age of Universe inaccurate?? Hi. i have a question that could already been nullified. Reading about the CMB it occurred to me that normal light is around 370 - 770 nm in wavelength and a microwave could be upto 30cm long.. That means light has been expanded a million fold?? (not sure) since...

Something that always got me thinking about is time is relative to the speed of the object (time dilation) how can we determine age of universe. Here is an example of what I'm thinking. When the big bang happened, imagine if certain parts of the big bang it got flung at different speeds...

Hi, one of physician from Yale Univ explained first 6 days in bible can be very similar to 16 billion years if we understand relativity. His theory tells that first day after the big bang, temperture of the universe was around 3 trillion times higher which means frequency of universe...

I am having trouble understanding how to use Hubble's constant to calculate the age of the universe. I know that 1/H = a distance on time equation, thus the age can be worked out i also know that the answer is in seconds and generally to a high power such as 17 However what puzzles me is...

Hi i am confused as to how to calculate the age of the universe with redshift say for example The age of the universe now is 13.4 billion years old (and a critical universe). How do i find the age of the universe if it was a redshift at say 0.6?? Do i have to find the scale factor first...

Homework Statement Assume that the current age of the universe is 13.4 billion years old, and that we live in a matter-dominated, omega_m = 1, critical universe, what is the age of the universe at redshift 0.6? HINT: use the current age of the universe to pin down the proportionality...

I was just thinking... :-p perhaps this is a dumb question & the two are unrelated. But, they say the universe is roughly 14 billion years old. My question would be, relative to who?

Coincidence of Universe age in $\Lambda$CDM and Milne cosmologies I wonder why... Just another example of the degeneracy* perhaps? Garth (*Now accepted for publication in Astrophysics and Space Science)

Hi i am confused as to how to calculate the age of the universe with redshift say for example The age of the universe now is 13 billion years old (and a critical universe). How do i find the age of the universe if it was a redshift at say 10?? Do i have to find the scale factor first? I...

Meaning of "age of universe" This question may have been addressed somewhat indirectly in other posts, but I'm interested in specifics. Exactly what assumptions about time (and the universe) are implied by a statement like, "The age of the universe is X years old"? In particular, does this...

As you go back in time,the gravitating bodies come closer and closer.So the gravitational field gets more and more intense.We know that clocks move slower in the presence of a gravitational field---so as you go back in time the clocks become slower and slower.So how can we say,using today's...

Recently I read that Universe is 156 Billion Light Years in size. Even if every thing moves at speed of light, a 13 Billion years old universe should not have radious more than 13 Billion years. Is it Correct? Can the rate of expansion exceed speed of light?

I'd be interested to hear people's comments. One thing especially. The current estimates are of the order of 20bn yrs and 5bn yrs respectively (the actual values are not important ... it's the 'order' of the ratio that interests me). So, our sun has been around for a quarter of the age of the...