"Measurements made by NASA's WMAP spacecraft have shown that the universe is 13.7 billion years old, plus or minus about 130,000 years."

https://starchild.gsfc.nasa.gov/docs/StarChild/questions/que....

Whoa, that's crazy precise. They got it down to the tens of thousands?

If so, seems like they should write "13.700 billion" for the first part. I'm a little suspicious of this number as-is.

Looking for a source for those numbers, I found this[0]:

> While previous estimates were 13.7 billion years old, give or take 130,000 years, new predictions hone in with more precision- at around 13.77 billion years, plus or minus 40 million years.

Which is much less precise and feels a lot more believable.

[0] https://www.labroots.com/trending/space/18295/light-bang-rev...

So NASA said "plus or minus 130,000 years" when they were actually off by about 70 million years?

That’s a misprint, the WMAP measurement was plus or minus 130 million years.

Naive question here - is the 13bn years relative to the surface of the Earth? I assume this matters right? If we're in a bit of a gravity well wouldn't the vacuum of space experience this time a bit longer?

According to [1], the ratio is about 5.56E-10, so I guess this would contribute about a year to the age of the universe, so.. not that much. I guess I answered my own question.

However, this does pose an interesting question about the age of the universe in extreme gravity wells doesn't it? Or am I misunderstanding something?

[1] https://www.quora.com/How-much-time-on-earth-is-1-hour-in-sp...

Well, given that there is no universal clock and time is defined locally for each observer, including each particle, it would be more strictly accurate to say that "the matter which later formed our solar system has experienced 13 billion years of time" since the Big Bang

or maybe 13 billion years is from the frame of reference of the Cosmic Microwave Background? that would make more sense. I'm going to check again then edit this comment.

(i am not a physicist, not an authoritative source on this)

edit: so it turns out that the age of the universe is given from the frame of reference of the CMB rather than from Earth's frame of reference.:

> Measurements of the cosmic background radiation give the cooling time of the universe since the Big Bang

> Cosmic time, or cosmological time, is the time coordinate commonly used in the Big Bang models of physical cosmology.[1][2][3] Such time coordinate may be defined for a homogeneous, expanding universe so that the universe has the same density everywhere at each moment in time (the fact that this is possible means that the universe is, by definition, homogeneous). The clocks measuring cosmic time should move along the Hubble flow.

https://en.wikipedia.org/wiki/Cosmic_time

I have a question: Just over 20 years ago when the accepted view was that the expansion of the universe was slowing down, would you have backed that position with as much certainty as you are backing this one? That the universe is a mere 13.7 billion years old?

We cannot prove the absence of light in a place that is already so far away that it's light will never reach us. Do you agree? We can prove what we can observe, and from that proof we can make inferences about what we cannot observe.

The entire premise of dating our universe is based on its observed rate of expansion. This was accomplished by extrapolating data from observable light and tracing it back to the so called Big Bang.

I see a lot of problems with this one dimensional assumption, which to me seem really obvious.

First of all, let's assume that we actually got it right this time and accurately traced light back to the Big Bang - how can anyone be sure that it was the first and only Big Bang?

Pangea, the super continent, for instance - many may think of as a single place and time in history, but in fact it's more likely that many Pangea's have come and gone in various states as the planet roils on. There will likely be another in the far future.

Perhaps the Big Bang was merely a "localized" event and there are Big Bangs occuring in distant places whose light will never reach us. Perhaps we have gone through many Big Bang / Big Crunch cycles. We simply cannot prove it one way or the other, and so to take a strong position on this would be unscientific.

More food for thought - imagine that the universe has already been through a near infinite number of Big Bang / Big Crunch cycles, it begs the question, do we reset the clock every time or do we let it run?

In my opinion, currently accepted theory is akin to believing that the Earth is the center of the universe and the sun revolves around us. We were wrong about that too.

The problem here is that you are taking a simplified layman's description, making naive assumptions about it and then brazenly dismissing the whole of contemporary cosmology as if you have profound insights that went completely over the heads of some seriously smart physicists.

You then make an analogy about "Pangaea" as if you alone are the brilliant shining light of reason, but if you took just a small amount of time to read even Wikipedia you would find, for example, that several super-continents have formed and broken apart over the history of the Earth. The very first section of the Wikipedia article on Supercontinents lists eleven of them! [https://en.wikipedia.org/wiki/Supercontinent#Supercontinents...]

I for one see a lot of problems with your one dimensional analysis and obvious lack of awareness on these topics. In my opinion, your currently insufficient knowledge is akin to believing that the Earth is flat because you can't personally see curvature on the horizon.

Seriously though, I recommend you take the time to read about 'the entire premise of dating our universe', all the many decades of development, criticisms, refinements and confirmations of the current best theory. You'll find that it's an amazing subject, that all of your concerns have been poured over for the past century in great detail, that many brilliant people have worked out fantastically brilliant methods for figuring this out... and then finally, maybe, you'll be ready to read about the various cyclic cosmological models.

I get where you're coming from but there is a general frustration out there about physics that a lot of nerds share. We need kicks as well as truth or the heart won't be in it. People invest a lot of energy into something if they feel they are involved with the general effort because it gives meaning and we enjoy that. Our lay ideas will be incorrect - but the urge to ask questions being stifled by a existing body of understanding we don't understand makes us apathetic and prone to leveling.

Somebody like Graham Hancock is actually delivering more people to the pipeline of scientific understanding than Richard Dawkins. We don't want to hear it but it's true. Similar things are true of WebMD and doctors, Elon Musk and space research. All the time the domain experts are shooting themselves in the head because the true opposition isn't a cruder wrong idea - it's apathy. Creationists at least give a shit about what version of events took place, the population that doesn't care is much larger. There is no critical mass of creationists that is going to undermine scientific research but the universities being defunded by an apathetic public turning hostile because they believe we're a waste of dollars - that is only a matter of time.

Science and expertise are an ecology - the people on the edge only exist because of a bigger enterprise capable of providing support. So it's not great that the stories the general public and scientists tell themselves are starting to sound like a protagonist antagonist relationship.

This is a really great point and I believe it is (at least partially) driving the anti-science rhetoric that seems to be metastasizing. When a topic is inaccessible to the general public, and only experts in the field can understand it and hold a monopoly on information, then you inevitably start to see pushback against it.

That being said however, making certain fields more accessible to the populace often comes with the price of a false sense of understanding. You see this a lot in medicine with WedMD, where heuristics that largely ignore the deeper pathophysiology have empowered some to believe they are more knowledgeable than their doctors.

This must be doubly true for the more abstract forms of physics - where any simplified analogy is going to give rise to false notions via extrapolation. I think there has to be some sort of balance between the two

Here is a example solution for the WebMD problem - I think it's about empowerment and tribalism - in positive senses of those words.

In Japan there exists an institution called Ningen Dock. Almost nobody in the West has heard of it outside of Randox Research which is astonishing as most Japanese people visit it once a year. I believe this is a psycho-social-medical institution. It purports to be a medical institution but it's something more.

Youtubers describe their experiences of Ningen Dock if you're curious.

It works like this - most people in Japan visit the 'dock' - a metaphor from shipyards. There is a brain dock, a heart dock, a lung dock and so on. Every major hospital has this department where the patient is checked head to foot once a year. Here is the important part. They are given a grade sheet - the sort a schoolteacher awards students. Here you see your kidney was given a B-, a liver a C-. These are hints about your lifestyle choices. Perhaps you should feel bad. In one more year there will exist another Ningen Dock. I believe this institution is responsible for a superior resilience against lifestyle disease that overwhelms healthcare in other developed states. It's preventative healthcare taken seriously instead of mouthing platitudes about lifestyle choices while back in Western reality you're never far from a fatty who knows they're making mistakes. It could be you or me!

Now Sir Gwern and other analytical thinkers of HN will have spotted the problem. False positives leading to needless surgeries. This is how Western doctors are trained to think and they find Ningen Dock incomprehensible. If though we assume Japanese MDs are not idiots and positive externalities exist from the Ningen Dock then it could easily be paying for itself. The hypochondriacs don't menace the healthcare system. Their energy is redirected to superior choices. For everybody the locus goes away from the doctor and analysis and toward being responsible on your health to the best of your ability - guided by timely medical advice. The system also develops a giant database of longitudinal information which can be used to spot health patterns across populations - to enhance targeting of the analytical process. I'm sure there are lots of other tangible advantages I haven't mentioned.

So that is patient empowerment - but the tribalism aspect is important too. The system is saying to the people - we're on your side, we're on the same team, we are in your corner, we are working for you. A lot of people don't feel that way and it needs to be said. Think of the rise of ASMR videos. Hundreds of millions of people watching supposed doctors treating them. There's something there. Just the insistent affirmation would be positive for mental health.

>Somebody like Graham Hancock is actually delivering more people to the pipeline of scientific understanding than Richard Dawkins. We don't want to hear it but it's true.

This is a pretty bold statement. You are arguing that psuedoscience is resulting more people being scientific than actual science is?

Such an extraordinary claim needs some significant evidence behind it.

Is it really an extraordinary claim? In your own experience have you never settled for a poorer model of something, a lower resolution because you feel either you didn't have the cognitive resources to get there or you felt unmotivated? When the topic becomes more complex - this happens to more and more people.

If you have a compelling story you may be motivated to sip on the subject. After a time you probably shrug off the old understanding and get to something more robust and probably more scientific.

I acknowledge some people will head into annoying dead ends - but you have to respond to the question of whether you prefer some people to be wrong and some people get to better places - or if you want most of those people to have checked out altogether. After all it seems to me that longer people ponder on it the more it is they converge on something - often something true or useful. Those are your choices. If you want to call me a liar then I suggest taking this seriously means getting a whole lot better at telling stories that go in the direction you approve of instead of what to the inside looks like doubling down on accuracy but to the outside looks like obfuscation.

Practical test - A lot of scientists are concerned about CO2 emissions and climate change. A lot of the population thinks they're full of shit because of politics. Some people have noticed though - that there doesn't exist a conflict of interests in getting improved technologies that happen to reduce CO2 emissions. Just as many right wingers are going to buy passive houses, closed loop energy, solar panels, Teslas as left wingers. Instead of perusing this thought a lot of people veer off into sermonizing on the topic - but I have to wonder why anybody gives a shit about the means when it seems like pushing on one lever gets instant blowback and pushing on the technology lever wins friends every time. It's almost as if all these groups have ulterior motives different to the public facing ones.

I don't quite understand how we go from "Ancient aliens" to "real science" - I've never spoken to someone who believed in that stuff as the jumping off point that later went on to being curious about actual science when they weren't previously.

>Just as many right wingers are going to buy passive houses, closed loop energy, solar panels, Teslas as left wingers.

I also don't know that this is actually true. I as only able to find "what do you want to buy" polling for cars, but in a study surveying actual solar usage, it's 34% democrat and 20% republican.

https://www.autoblog.com/2016/10/26/democrats-tesla-republic...

https://grist.org/article/republicans-are-buying-rooftop-sol...

But I think this is also a false premise - that somehow conspiracy theory nuts have the same impact on public perception of science as one of the most public scientific issues with consensus from tens of thousands of scientists including basically 100% of the leading experts in the field. And the fact that there are long term economic advantages for things like solar, etc. that don't take into account at all whether or not you believe in man made climate change.

True - but most people never become scientists - not even amateurs - but there exists a flourishing industry of science books for people who are a bit science curious. Scott Alexander used to be a giant Hancock fan - anecdotal I know but he later realized it was sort of bullshit - but still was interested in deep archaeology. I'll call that a win.

On the stats - that's a rabbit hole I won't go down today but every time I've seen people talk about alternatives to the system the left and right become like a long married couple ending each other's sentences.

>And the fact that there are long term economic advantages for things like solar, etc. that don't take into account at all whether or not you believe in man made climate change.

Sure.

> But I think this is also a false premise - that somehow conspiracy theory nuts have the same impact on public perception of science as one of the most public scientific issues with consensus from tens of thousands of scientists including basically 100% of the leading experts in the field.

There I think you're making a mistake. Literary people think Proust is awesome. A lot of people have read Dan Brown. Who is having more impact? You're making a face now - I can see through the interneticals.

This is just pedantry. Don't get me wrong, these are interesting questions, questions that should be asked and should be thought about, even if the answers are likely unknowable. But taking issue with the age of the universe because we don't know what existed before isn't useful.

Age is a relative thing. I say I'm xx years old based on the date of my birth. But I existed as a fetus before then. I existed as an ovum before that. I existed as stardust for billions of years before that. Perhaps I can mull over what it means to exist, and when "me" came to be, but when I have to enter my age while filling out some form I'm not going to write a philosophy essay. For practical purposes I am xx years old, and for practical purposes the universe is 13.7 billion years old.

I think you are generally critiquing assumptions that most astrophysicists are not making. Most Theorists would not claim with confidence that the big bang was the first or only one, or that future big bangs are not possible. I think your criticism is more valid for the way the history of the universe is portrayed in news articles and high school text books.

The term "multiverse" is used to describe the collection of multiple universes.Some have speculated that time has no direction in the multiverse and that time in each universe may be different. If our universe is cyclic, it makes sense to reset the clock because it may have run in a different direction last time or next time.

> Perhaps the Big Bang was merely a "localized" event and there are Big Bangs occuring in distant places whose light will never reach us. Perhaps we have gone through many Big Bang / Big Crunch cycles.

This was always my view of the state of the universe from childhood onward. The Void of space is infinite, and within that Void our universe could be one of an infinite number of other universes that we will never know about because they are so far outside our ability to observe them. Perhaps there is as as much relative distance between universes in the Void as there is between galaxies in our own universe.

This concept is the only way I've ever been able to accept that our own universe has a measurable size.

I don't think your childhood view holds up with contemporary views. My understanding is that 3 dimensional space, as well as time are properties of our local universe. There is no space outside the big bang and between universes if multiple exist

That's exactly what I have such a hard time wrapping my head around: The concept that there is not even a Void outside of the borders of our own universe, that existence itself doesn't, well, exist. The fact that "space" (as we define it) is finite just feels so wrong, so impossible.

To be frank, I totally agree. I don't think our brains can comprehend what existence would mean without 3 dimensions and time.

> Just over 20 years ago when the accepted view was that the expansion of the universe was slowing down

Was it ever a mainstream view? I thought it was just a conjecture, leading to the 'big crush', and was disproven long ago, way more than 2 decades ago.

> The entire premise of dating our universe is based on its observed rate of expansion

Also there's the cosmic microwave background radiation. We have mapped it, and this has also allowed us to corroborate when the universe has formed, what temperature it had, and when large scale structures appeared.

There's probably other sources that allows us to estimate the age of the universe.

> how can anyone be sure that it was the first and only Big Bang?

We can't. But it is an irrelevant conjecture outside of philosophy, we can't observe anything before the big bang.

> but in fact it's more likely that many Pangea's have come and gone in various states as the planet roils on

Sure, but that's a planet. We can't extrapolate much from that and apply to the universe at large.

> Perhaps the Big Bang was merely a "localized" event and there are Big Bangs occuring in distant places whose light will never reach us

Unobservable, therefore unfalsifiable, therefore unscientific. Philosophy again.

> imagine that the universe has already been through a near infinite number of Big Bang / Big Crunch cycles

Unless the rate of expansion starts to slow down or we have indication that it will ever reverse, there's no big crunch. The rate of expansion is increasing

> currently accepted theory is akin to believing that the Earth is the center of the universe and the sun revolves around us

Not really. You are dismissing generations of people dedicated to the study of these things. We have a pretty good idea of what's going on based on the scientific method, not conjectures from single individuals.

There are things that we don't know yet. On a macroscopic scale, dark matter. Things don't really behave as they should based on observations, so this is why we have dark matter as a hypothesis. There could be another mechanism, research is ongoing. But as far as the macro universe goes, that's the major thing we don't understand yet.

Most discoveries will likely come from a better understanding of the 'building blocks', of which quantum physics is at the forefront.

There's probably much more we don't know yet. But the age of the universe, as we observe it, is not among them.

>Unless the rate of expansion starts to slow down or we have indication that it will ever reverse, there's no big crunch. The rate of expansion is increasing

Unless space wraps around like a globe and we'll all meet at the "south pole" (with the big bang being the "north pole") or something to that effect. Which is itself wild, unfalsifiable conjecture, but there are other ways for a Big Crunch to happen other than the expansion of space slowing down or reversing

> Unobservable, therefore unfalsifiable, therefore unscientific. Philosophy again.

I completely agree. Apologies if my comment above rubbed anyone the wrong way. The point you just made was my overall point. Our concept of time is confined to our current existence / cycle - that's what I meant by the sun revolving around the Earth comment, but others were correct when they responded that as a current metric that's not really useful.

> "Unless the rate of expansion starts to slow down or we have indication that it will ever reverse, there's no big crunch. The rate of expansion is increasing"

What if it is increasing because it is falling towards a great mass on the other side of the universe? That would still count as a big crunch in my opinion.

> "Was it ever a mainstream view? I thought it was just a conjecture, leading to the 'big crush', and was disproven long ago, way more than 2 decades ago."

How would one disprove the ultimate fate of the universe?

> We have a pretty good idea of what's going on based on the scientific method, not conjectures from single individuals.

Where do our theories come from, if not single individuals?

Sorry to bikeshed, but I was struck by the word "likely" in your parenthetical. Are there models of the universe that predict our observable universe is _not_ a subset of the entire universe? How would one describe cosmological expansion in such a model?

It depends on the size and topology of the entire universe. It's possible the universe is smaller and sort of wraps around: literally, objects that appear far away are just past images of the back of objects that are closer to us.

More boringly, measurements of the curvature of the universe mean this is probably not the case.

The Cosmic Microwave Background Radiation is a pretty uniform field that exists over the entirety of the observable universe. It was created in the earliest days in our universe. The fact that it exists everywhere we look with high regularity lets us guess that we're only a subset of a larger universe. There are many theories about the unobservable parts of the universe but these are impossible to test with any foreseeable technology that doesn't fundamentally break our understanding of physics.

One analogy I've heard: Imagine the big bang split into 4 spheres and they accelerated away from each other. Because they'll all be expanding and accelerating, there could be 4 equally sized spheres of stuff just like our own, but it would be impossible for us to observe them. Change the number 4 to 2 or 1000 or n. We really would have no idea.

A testable hypothesis is a strong standard in science. Most scientists don't worry about things that cannot or more importantly, will probably never be testable. They can be fun to think about but that's pretty much it.

Some weird geometry where space is curved into a four dimensional sphere. The sphere gets bigger, adding space between all the points. If the sphere is exactly the size of the observable universe, then the observable universe and universe would be the same thing.

How can we observe things over 40 billion light years away if they've only been around to emit light for 13 billion years?

The universe has been expanding ever since the Big Bang. Things that are very far away are moving away from us at speeds "faster" than light. No, they're not violating the cosmic speed limit. The fabric of spacetime itself is expanding everywhere, and that makes objects at very large distances apart get even further apart faster than a lightspeed traveler could move them.

https://www.space.com/33306-how-does-the-universe-expand-fas...

They were closer to us when they emitted that light. They've since moved further away.