The Universe, who is fascinated by that?

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#1624664 6-Sep-2016 15:37

Rikkitic:

I stand corrected. Apparently human evolution is considered to have begun about 6 million years ago. I thought it was more recent.

How do you define human? Very subjective.

Mike

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#1624674 6-Sep-2016 15:46

For the purpose of this specific topic, I subjectively define it as the evolutionary line that is considered to have led to modern mankind. I am well aware that any definition is arbitrary to a degree and I'm sure we could start all the way back from the first bacterium or anything in-between, but 6 million years ago seems to be generally agreed as the branch on the tree of life that led to us. That works for me.

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#1624720 6-Sep-2016 17:16

Looks like 15 million years ago. Biological life started about 4.1 billion years ago

Family

Hominidae

Great apes: humans, chimpanzees, gorillas, and orangutans—the hominids

Subfamily

Homininae

Humans, chimpanzees, and gorillas (the African apes)

Tribe

Hominini

Genera Homo, Pan, and the Australopithecines

5.8

Subtribe

Hominina

Genus Homo and close human relatives and ancestors after splitting from Pan—the hominins

2.5

Genus

Homo

Humans

2.5

Species

(Archaic) Homo sapiens

Neanderthals

0.5

Subspecies

Homo sapiens sapiens

Anatomically modern humans

0.2

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#1624984 7-Sep-2016 10:50

It's hard to understand how everything in the universe started from a dot.

Even harder than that, modern physics theory tells us that it didn't even start from a dot - it started from NOTHING. That's really something!

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#1624989 7-Sep-2016 11:21

No-one really understands it, not the experts and certainly not anyone here. Through the Wormhole just did an episode on nothingness and I have seen a couple other documentaries recently that suggest that space is not empty, but filled with fundamental particles or other forms of energy, so nothing is not really nothing and I suppose that means something can emerge from it. A lot of it is just semantics and how we define things within the limits of our comprehension. What we think of as nothing may not be nothing at all. At least, I think so.

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#1625006 7-Sep-2016 11:48

The zero energy universe hypothesis is (IMO) the most ideologically pure, as it doesn't need to consider a "before" or "creator", leaving only the problem defining how a quantum fluctuation could happen before spacetime existed. That becomes a philosophical question, as if it didn't happen there'd be no possibility of anything observing it, so it's consistent with the anthropic principle - that it happened so that it could be observed to have happened. It even allows for the strong anthropic principle - that it happened specifically in the way that it did, so that you (and I) would be created. That doesn't preclude the possibility of a god - but makes the concept of a paternalistic god seem very unlikely. When you're feeling insignificant and mortal, just think that you won't cease to exist in expanding spacetime, only at the point in time that you observe as "now".

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#1625007 7-Sep-2016 11:49

mclean:

It's hard to understand how everything in the universe started from a dot.

Even harder than that, modern physics theory tells us that it didn't even start from a dot - it started from NOTHING. That's really something!

That's not surprising. We can't even understand our own brain. In fact no one even knows why we sleep.

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#1625024 7-Sep-2016 12:44

mclean:

It's hard to understand how everything in the universe started from a dot.

Even harder than that, modern physics theory tells us that it didn't even start from a dot - it started from NOTHING. That's really something!

Ah - it started from Seinfeld!

Sometimes I just sit and think. Other times I just sit.

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#1625235 7-Sep-2016 19:11

mclean:
It's hard to understand how everything in the universe started from a dot.

Even harder than that, modern physics theory tells us that it didn't even start from a dot - it started from NOTHING. That's really something!

I don't think there is a theory of the start of the universe yet. Relativity doesn't go back that far in time. And I think the quantum stuff has a few gaps still.

The field theory for general relativity (as I understand it) says that the universe has an internal pressure pushing out which is what is causing it to expand. As far as I can see that holds true when time (t) is > 0. It probably also holds true when t=0 but that's quantum I guess.

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#1625637 8-Sep-2016 13:17

MikeAqua:
How do you treat infinity in arithmetic?

Infinity - Infinity = what

Are two separate infinities the same size?

Can you even have two separate infinities? One infinity should spatially preclude a 2nd infinity existing?

Or can infinities nest like Russian dolls?

After all everything should fit in an infinity?

Hi,

If you are interested in bending your mind, you might want to investigate transfinite arithmetic. It's a whole bunch of fun, if you like that sort of thing.

Have you realised that when you count from 0 to 1 you have just encompassed an infinity of real numbers? And we can map each countable integer into the range from 0 to 1 inclusive. It's full of cool concepts like that

Cheers

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#1625657 8-Sep-2016 13:28

TwoSeven:
mclean:
It's hard to understand how everything in the universe started from a dot.

Even harder than that, modern physics theory tells us that it didn't even start from a dot - it started from NOTHING. That's really something!

I don't think there is a theory of the start of the universe yet. Relativity doesn't go back that far in time. And I think the quantum stuff has a few gaps still.

The field theory for general relativity (as I understand it) says that the universe has an internal pressure pushing out which is what is causing it to expand. As far as I can see that holds true when time (t) is > 0. It probably also holds true when t=0 but that's quantum I guess.

There is a very good book called The First Three Minutes which gives a good explanation of the current theories about the big bang, inflation and so on. Written at a lay level , but some quite deep concepts. It's nice because they caught explains the current thinking and points out the difficulties for each along the way..

I would be interested in understanding the comment about field theory and general relativity. I have been away from theoretical physics for some time, and was not aware that there was such a thing. Any references?

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#1630769 15-Sep-2016 11:10

Ok, I'll admit it, I am fascinated by the Universe .

But I've skipped over most of the thread as the Big Bang stuff, string theory and infinite universi strains my brain.

Though I do enjoy The Big Bang Theory on TV, does that also count ? That doesn't strain the brain too much..

This is awesome:

A billion stars of the Milky Way captured in space map of night sky

http://www.nzherald.co.nz/space/news/article.cfm?c_id=325&objectid=11710104

Have also been following the Electron rocket story - I'll be keen for a road trip to Mahia when this all starts up.

I also have APOD ( Astronomy pic of the day) running on two of my PC's, and also on my S5.

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#1650764 13-Oct-2016 23:28

Here's something new and reasonably interesting - at least worthy of further investigation:

Original paper:

https://arxiv.org/ftp/arxiv/papers/1610/1610.03031.pdf

Very cautious comment from SETI:

https://seti.berkeley.edu/bl_sdss_seti_2016.pdf

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#1656226 22-Oct-2016 16:50

Perhaps the rate of expansion of the universe isn't accelerating:

The ‘standard’ model of cosmology is founded on the basis that the expansion rate of the universe is accelerating at present — as was inferred originally from the Hubble diagram of Type Ia supernovae. There exists now a much bigger database of supernovae so we can perform rigorous statistical tests to check whether these ‘standardisable candles’ indeed indicate cosmic acceleration. Taking account of the empirical procedure by which corrections are made to their absolute magnitudes to allow for the varying shape of the light curve and extinction by dust, we find, rather surprisingly, that the data are still quite consistent with a constant rate of expansion.

http://www.nature.com/articles/srep35596

There has been speculation that there were flaws in the standard candle model for type 1a supernovae:

https://science.slashdot.org/story/15/04/12/037220/supernovae-may-not-be-standard-candles-is-dark-energy-all-wrong

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#1656236 22-Oct-2016 17:21

Fred99:

Perhaps the rate of expansion of the universe isn't accelerating:

The ‘standard’ model of cosmology is founded on the basis that the expansion rate of the universe is accelerating at present — as was inferred originally from the Hubble diagram of Type Ia supernovae. There exists now a much bigger database of supernovae so we can perform rigorous statistical tests to check whether these ‘standardisable candles’ indeed indicate cosmic acceleration. Taking account of the empirical procedure by which corrections are made to their absolute magnitudes to allow for the varying shape of the light curve and extinction by dust, we find, rather surprisingly, that the data are still quite consistent with a constant rate of expansion.

http://www.nature.com/articles/srep35596

There has been speculation that there were flaws in the standard candle model for type 1a supernovae:

https://science.slashdot.org/story/15/04/12/037220/supernovae-may-not-be-standard-candles-is-dark-energy-all-wrong

The science of scientists are so flawed they can't even tell if butter or margarine is good or bad, yet people have complete faith in their hypothesis of the beginning of time and what T-rex looked like.

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