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Question: How old is the universe?
Billions of years old - 29 (82.9%)
Less than 7,000 years old - 1 (2.9%)
Other - 5 (14.3%)
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Author Topic: Age of the universe?  (Read 2742 times)
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BillO
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« on: Aug 19, 2017, 05:18PM »

An important question that keeps coming up in religious discussion.  Some folk from the Judaeo-Christian view are fine with the universe being old as are most atheists.  I've never heard of an atheist that thought it was under 7K years, but there could be some.  Comments are optional.
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« Reply #1 on: Aug 19, 2017, 06:43PM »

We postulate that the Big Bang (that set everything in motion) occurred 14 billion years ago (100 billion dog years ;-) ).  But there is also a postulation that the Big Bang was not the first one and there may have been others before.  This is a concept I really have a hard time understanding, but maybe we can find evidence that this is so.  Meanwhile, my hour upon the stage will be drawing to a close and I do not expect to see the next eclipse after the one Monday.  Our lives are but a brief second in the scale of the cosmos.
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« Reply #2 on: Aug 19, 2017, 08:36PM »

For everything to start expanding at the moment of the Big Bang, that everything had to already exist prior to the moment of the Big Bang. We can trace the start of the expansion at 13.8 billion years, but I don't think there is yet a prevailing theory for what all that matter and energy was behaving prior to that sudden expansion. Or even for how it behave after the explosion but before it was cool enough for the laws of conventional physics to apply.

Now the question after that, is - is the universe part of a multiverse, and if so, how does THAT work!
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« Reply #3 on: Aug 20, 2017, 07:26AM »

But there is also a postulation that the Big Bang was not the first one and there may have been others before.
I'm not sure I buy into the oscillating universe theory at all.  There is no evidence for this, and as far as I can see, there could be no evidence of it.  If the universe collapses altogether (big crunch) such that it ceases to exists, for even the briefest moment, there would remain nothing wherein any evidence could be carried forward.

That said, in 2011 the Nobel prize in physics went to group the showed the rate at which the universe is expanding was increasing.  As of 2016, due to data from better surveillance of the universe, some in the physics community are questioning that result saying that the additional evidence may suggest steady-state expansion.  So at this time, even the possibility the 'big crunch' is in doubt.  Without the big crunch we can't have an oscillating universe.
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« Reply #4 on: Aug 20, 2017, 07:38AM »

For everything to start expanding at the moment of the Big Bang, that everything had to already exist prior to the moment of the Big Bang. We can trace the start of the expansion at 13.8 billion years, but I don't think there is yet a prevailing theory for what all that matter and energy was behaving prior to that sudden expansion. Or even for how it behave after the explosion but before it was cool enough for the laws of conventional physics to apply.
 
Now the question after that, is - is the universe part of a multiverse, and if so, how does THAT work!

This is the problem--yeah. It seems that we have only two options we can even try to conceive of. The cosmos came into existence at some point, in which case there would have had to have been nothing before that, and what does that mean? Or the cosmos has simply always existed, but how can anything have no beginning or end?
 
We can't really conceive of what it would mean for time to come into existence, or how nothing could have existed before there was anything, or how something could have no beginning or end--that something has just always existed and always will, or what could be beyond the cosmos or how the cosmos could have no spatial boundaries, or how the smallest particle can be made of nothing but itself--indivisible. Applied infinities just don't compute on the natural gear we have. Thinking about these kinds of things deeply can get you a brief high--I suspect it's synaptic overload or something like that.
 
Our brains may just not be powerful enough or set up right to deal with these kinds of things. We simply have no viable or actual answer as yet, and none in sight. The large majority feels as if it makes sense to insert God did it. as if that's an actual answer rather than the logical equivalent of just calling it magic. This is another human brain thing--we don't deal well with uncertainty--particularly uncertainties that are important to us. Most believers aren't so anxious and self-absorbed they need to feel like they have all the best toys though--most in my experience are satisfied with enough.
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« Reply #5 on: Aug 20, 2017, 07:46AM »

For everything to start expanding at the moment of the Big Bang, that everything had to already exist prior to the moment of the Big Bang.
This sounds like a sensible assumption based on conventional thinking.  However, nothing about the initiation of the big bang is conventional at all, so your statement does not necessarily follow or make sense in terms of what was happening then.

The first problem is of course, if the big bang had not created the universe yet, where was 'everything' existing?

The Zero-Energy Universe  hypothesis is gaining momentum and helps explain where 'everything' came from.  Still just in its infancy, but definitely a better approach than trying to explain where 'everything' was before there was a place for it.

The muti-verse has been discussed for a fairly long time.  At this point it's still just a cognitive pass time, but an interesting one.
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« Reply #6 on: Aug 20, 2017, 08:40AM »

I heard some scientist recently say that if the asteroid that wiped out the dinosaurs had been 5 minutes later, it wouldn't have been nearly as devastating. T-Rex would still be around. And we wouldn't. But maybe T-Rex would have evolved and learned to play trombone by now, so this forum might still exist.

Updated with link to article:

https://www.washingtonpost.com/news/speaking-of-science/wp/2017/05/18/why-these-researchers-think-dinosaurs-were-minutes-away-from-surviving-extinction/?utm_term=.f84f512d2ac8
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BillO
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« Reply #7 on: Aug 20, 2017, 03:11PM »

I heard some scientist recently say that if the asteroid that wiped out the dinosaurs had been 5 minutes later, it wouldn't have been nearly as devastating. T-Rex would still be around. And we wouldn't. But maybe T-Rex would have evolved and learned to play trombone by now, so this forum might still exist.

5 minutes?  We can do the math and see.  It was not a glancing blow.  From the evidence collected (and I freely admit I am not a geologist, so I can't criticize their findings) the meteor came in at nearly 90 degrees and at about 70,000 KPH.  So when it hit it hit at approximately dead center of the earth from it's perspective.  We don't know how aerodynamic the meteor was, or if it was rotating so lets assume a worst case such that it would have to renter at at least 10 degrees to make impact in such a way as serious damage to the planet would occur.

I wish this forum allowed TEX editing.  You'll have to trust me on some of my math as I can't show it to you.

So, the earth moves through it's orbit at about 108K kph and has a radius of about 6.4K kM.  We'd hit at 10 degrees at about 83% of that or about 5.3K kM.  At 108K kph the earth will move about 1.8K kM per minute.  Therefore anything beyond 3 minutes late would have been fairly safe.

5 minutes and we would barely have had our hair rustled - so to speak.  Whoever the scientist was, he was right.  Good!
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« Reply #8 on: Aug 20, 2017, 03:27PM »

Our brains may just not be powerful enough or set up right to deal with these kinds of things.
Indeed, you are most certainly right.

About 5200 years ago the Sumerians realized we didn't have the head for numbers and created a tool (writing) to assist us.  We've been inventive enough to conjure up new tools along the way that help us out.  The computer is a really good one that can be re-configured almost endlessly.  We're pretty good at abstraction, and I feel confident we'll develop the tools to assist with this eventually.  Just a matter of beating our heads against the wall long enough for that to happen.
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« Reply #9 on: Aug 20, 2017, 03:34PM »



I heard some scientist recently say that if the asteroid that wiped out the dinosaurs had been 5 minutes later, it wouldn't have been nearly as devastating...

I recall the premise of "When Worlds Colide" was that the first encounter was a near miss but it circled around and smacked the Earth on the second pass.


BTW, if you like seeing planets get flung out of their orbits, try Super Planet Crash.
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« Reply #10 on: Aug 20, 2017, 04:31PM »

5 minutes?  We can do the math and see.  It was not a glancing blow.  From the evidence collected (and I freely admit I am not a geologist, so I can't criticize their findings) the meteor came in at nearly 90 degrees and at about 70,000 KPH.  So when it hit it hit at approximately dead center of the earth from it's perspective.

http://www.bbc.com/news/science-environment-39922998
 
How are you deriving a dead center impact from 90º and 70k KPH?
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« Reply #11 on: Aug 20, 2017, 04:51PM »


http://www.bbc.com/news/science-environment-39922998
 
How are you deriving a dead center impact from 90º and 70k KPH?
The 70K kph is not important to the derivation, only in calculating the minimum angle before the atmosphere would deflect it.

If it hits at 90 degrees, it's normal to the surface.  If it's normal to the surface it's in direct line with the center of mass, if you are approaching a sphere directly towards it's CoM, you are hitting it dead center.

IOW ... You can hit a sphere dead center at any point on the sphere as long as you are hitting it normal to its surface.

Another way to think of it.  If you (Byron) were riding on the meteor and it was coming in to hit the earth at 90 degrees, you would see yourself head directly at the center of the 'disk' you see before you.  Regardless of the point you are heading for ... the point of impact.



Another fun fact.  In this case it was near the equator, which is convenient.  It means it came in + or - 23.5 degrees from the ecliptic, making it likely that it was local (solar system) asteroid.
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« Reply #12 on: Aug 20, 2017, 05:18PM »

I'm not a scientist and I'm really not up on the scientific theories involved in the creation of the Universe.  I do believe that the age of the Earth is older than a literal interpretation of Genesis would allow for.  There are basically two schools of understanding of the Genesis text some interpretations allow that the 7 days of creation were literally 24 hour days as we know them today (I find this view very difficult to defend myself).  Others believe that the term day in this case denotes an undetermined period of actual time, and not a literal 24 hour day. If you dismiss the 24 hour day, and allow that the exact order of events may have differed from the Genesis story it is easy to allow for a God driven creation of the Universe that is in line with what the scientists are discovering. 
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« Reply #13 on: Aug 20, 2017, 05:24PM »

If you dismiss the 24 hour day, and allow that the exact order of events may have differed from the Genesis story it is easy to allow for a God driven creation of the Universe that is in line with what the scientists are discovering. 


How I you reconcile evolution with the idea of creation?
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« Reply #14 on: Aug 20, 2017, 05:50PM »



How I you reconcile evolution with the idea of creation?
Adam and Eve were amoebas?

Easy enough really, God influenced the evolutionary process to produce man.

You could make the bible work with a little editing and by providing a "Readers Guide" to workable interpretation.  I'd probably still be a skeptic, but I'll bet there would be far fewer of us.  The orthodoxy and the fundamentalists are and will be responsible for the continued decline of religion.
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« Reply #15 on: Aug 20, 2017, 06:08PM »

The 70K kph is not important to the derivation, only in calculating the minimum angle before the atmosphere would deflect it.

Yeah ... realized what 90º means when I started reading this again.
 
D'oh!
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« Reply #16 on: Aug 20, 2017, 06:47PM »

I can't help but wonder when the Earth & moon STOPPED getting hit with meteors?
Seems the moon is pretty well shot up,  so to speak, with craters,  and here on Earth there are several well documented craters fairly close together,  relatively speaking.

So,  how shy & when did THAT stop??

My weird thinking at 3AM when I can't shut my brain off....



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« Reply #17 on: Aug 20, 2017, 07:12PM »

Quote
I can't help but wonder when the Earth & moon STOPPED getting hit with meteors?


After a few billion years the planets have cleared out most of the seriouly large things they could collide with.

There really hasn't been a cessation however. The collision rate is approaching zero but will never be zero.

The moon, with no atmosphere to shield it, is still getting visibly smacked fairly often

Impact! New Moon Craters Are Appearing Faster Than Thought

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« Reply #18 on: Aug 20, 2017, 07:25PM »

I can't help but wonder when the Earth & moon STOPPED getting hit with meteors?
Seems the moon is pretty well shot up,  so to speak, with craters,  and here on Earth there are several well documented craters fairly close together,  relatively speaking.

So,  how shy & when did THAT stop??

My weird thinking at 3AM when I can't shut my brain off....



Eric

Eric, it's only 10:00pm here at EDT.  It's only 8:00 where you are.

Anyway,  Meteor impacts have not stopped.  They may have slowed down, and the reason for that is because, well, a lot of the natural space junk  has landed somewhere in the solar system.  We only got so much at the point of formation of this system.  IOW, we are running out stuff to hit us (earth and the moon).  Nonetheless, NASA have a whole department that eat, live and breath just this subject, so let me turn it over to them with this quote:

" On average, 33 metric tons (73,000 lbs) of meteoroids hit Earth every day, the vast majority of which harmlessly ablates ("burns up") high in the atmosphere, never making it to the ground. The Moon, however, has little or no atmosphere, so meteoroids have nothing to stop them from striking the surface. The slowest of these rocks travels at 20 km/sec (45,000 mph); the fastest travels at over 72 km/sec (160,000 mph). At such speeds even a small meteoroid has incredible energy -- one with a mass of only 5 kg (10 lbs) can excavate a crater over 9 meters (30 ft) across, hurling 75 metric tons (165,000 lbs) of lunar soil and rock on ballistic trajectories above the lunar surface.

The lunar impact rate is very uncertain because observations for objects in this mass range are embarrassingly few -- a single fireball survey conducted by Canadian researchers from 1971 to 1985. Clearly more observations are needed if we are to establish the rate of large meteoroids impacting the Moon.

But why look at the Moon? We need to understand the numbers of meteoroids across a range of sizes so we can evaluate the threat to spacecraft.  Small meteoroids are measured with radar as they ablate in Earth’s atmosphere.  Larger meteoroids are less abundant so a large collecting area is needed to measure a statistically significant sample.  The surface of the Moon provides millions of square kilometers of collecting area we can see from Earth."


And I'll add to that this NASA quote:

“On March 17, 2013, an object about the size of a small boulder hit the lunar surface in Mare Imbrium,” Bill Cooke of NASA’s Meteoroid Environment Office said in a statement. “It exploded in a flash nearly 10 times as bright as anything we’ve ever seen before.”

PS:  Robert beat me to it...
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« Reply #19 on: Aug 20, 2017, 07:43PM »

Eric, it's only 10:00pm here at EDT.  It's only 8:00 where you are.

Anyway,  Meteor impacts have not stopped.  They may have slowed down, and the reason for that is because, well, a lot of the natural space junk  has landed somewhere in the solar system.  We only got so much at the point of formation of this system.  IOW, we are running out stuff to hit us (earth and the moon).  Nonetheless, NASA have a whole department that eat, live and breath just this subject, so let me turn it over to them with this quote:

" On average, 33 metric tons (73,000 lbs) of meteoroids hit Earth every day, the vast majority of which harmlessly ablates ("burns up") high in the atmosphere, never making it to the ground. The Moon, however, has little or no atmosphere, so meteoroids have nothing to stop them from striking the surface. The slowest of these rocks travels at 20 km/sec (45,000 mph); the fastest travels at over 72 km/sec (160,000 mph). At such speeds even a small meteoroid has incredible energy -- one with a mass of only 5 kg (10 lbs) can excavate a crater over 9 meters (30 ft) across, hurling 75 metric tons (165,000 lbs) of lunar soil and rock on ballistic trajectories above the lunar surface.

The lunar impact rate is very uncertain because observations for objects in this mass range are embarrassingly few -- a single fireball survey conducted by Canadian researchers from 1971 to 1985. Clearly more observations are needed if we are to establish the rate of large meteoroids impacting the Moon.

But why look at the Moon? We need to understand the numbers of meteoroids across a range of sizes so we can evaluate the threat to spacecraft.  Small meteoroids are measured with radar as they ablate in Earth’s atmosphere.  Larger meteoroids are less abundant so a large collecting area is needed to measure a statistically significant sample.  The surface of the Moon provides millions of square kilometers of collecting area we can see from Earth."


And I'll add to that this NASA quote:

“On March 17, 2013, an object about the size of a small boulder hit the lunar surface in Mare Imbrium,” Bill Cooke of NASA’s Meteoroid Environment Office said in a statement. “It exploded in a flash nearly 10 times as bright as anything we’ve ever seen before.”

PS:  Robert beat me to it...

Bill,  This thread just happened to be going tonight,  but got me thinking about the times I wake up at 3 & start thinking....
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