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Old Jul 24th 2015, 08:53 AM   #11
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First an apology.
For taking the thread off topic, when I thought you had abandoned it by not replying to my post#2

1. A 2D object cannot exist other than in the imagination
There are an infinite number of real 2D surfaces in a 3D cube!

2. A hole in an object consists of space (ether if you will) and potentially various forms of energy but certainly not "nothing"
If I draw one circle inside another, or if you prefer 3D then take one ball inside another so the radius of the first is always larger than the radius of the second, and then take the limit as the two radii tend to zero, what happens to the volume between the balls?

So how about a reply to post#2?
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Old Jul 24th 2015, 09:09 AM   #12
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As it happens, I also saw the TV program last night,
For the end of the universe (Heat Death) Professor Brian Cox almost says straight out that there would be no time at the end.
What he does say is that there is no change.
I would suggest that if there is no change (with respect to time) then there is no time.
A similar argument can then be levelled at the start of the universe, if the singularity is just sitting there not changing...

An alternative interpretation is that the universe is a 4 dimensional construct of space and time (spacetime), beyond the edge of this construct there is no space or time.
(see A Brief History Of Time)
There are various theories of higher dimensions with universes being 4D "branes" within these higher dimensions,
However position within these higher dimensions would not be measured via distance or time,
they would have their own, completely different, dimensional co-ordinates.
How causality within these higher dimensional realms would or could affect our 4D universe is too mind boggling for me to grasp...
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Old Jul 24th 2015, 09:55 AM   #13
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Originally Posted by jonathancollins View Post
Hi CHIPB,

How do you conclude that "time may not have existed prior to t=0"?
I don't conclude this at all - notice I wrote "may." No one knows. But here's a quote from Stephen Hawking about it:

"The conclusion of this lecture is that the universe has not existed forever. Rather, the universe, and time itself, had a beginning in the Big Bang, about 15 billion years ago. The beginning of real time, would have been a singularity, at which the laws of physics would have broken down."

This is from http://www.hawking.org.uk/the-beginning-of-time.html
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Old Jul 25th 2015, 01:06 AM   #14
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Originally Posted by ChipB View Post
I don't conclude this at all - notice I wrote "may." No one knows. But here's a quote from Stephen Hawking about it:

"The conclusion of this lecture is that the universe has not existed forever. Rather, the universe, and time itself, had a beginning in the Big Bang, about 15 billion years ago. The beginning of real time, would have been a singularity, at which the laws of physics would have broken down."

This is from http://www.hawking.org.uk/the-beginning-of-time.html
There is a ground swell of opinion that there must have been a precursor to the dense state of the universe before the rapid expansion. The notion of something arising from nothing fundamentally rails against the sum of all human knowledge and intuition about the universe in the same way that the notion of a flat earth gave way to the notion of a spherical earth. The inability of known laws of physics to cope with the initial conditions at the point of the rapid expansion does not preclude those conditions rather it proves that either the known laws of physics are incomplete or that the supposed initial conditions (the singularity) are incorrect (or both).

It is interesting that Hawking uses the term "real time" which appears to reveal an uncertainty about the nature of time. I suspect that Hawking and others regard time as a human construct that fits most conveniently into a description of the rapid expansion epoch.

There is no direct evidence that time is actually part of the fabric of the universe. It is probable that human beings dreamt up the notion of time as a convenient way of 2 or more people being in the same location to share a task. For example an agreement for 2 people to meet for a hunt at sunrise on the bank of a river next to a large rock is in effect a synchronisation of the event of sunrise with 2 people and a unique geographical point on the planet. The human notion of time serves the purpose of accurately synchronising events for a species that owes much of its success to organised cooperative behaviour.(see http://whatswaving.weebly.com/an-alt...elativity.html).
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Old Jul 25th 2015, 02:26 AM   #15
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Originally Posted by MBW View Post
As it happens, I also saw the TV program last night,
For the end of the universe (Heat Death) Professor Brian Cox almost says straight out that there would be no time at the end.
What he does say is that there is no change.
I would suggest that if there is no change (with respect to time) then there is no time.
A similar argument can then be levelled at the start of the universe, if the singularity is just sitting there not changing...

An alternative interpretation is that the universe is a 4 dimensional construct of space and time (spacetime), beyond the edge of this construct there is no space or time.
(see A Brief History Of Time)
There are various theories of higher dimensions with universes being 4D "branes" within these higher dimensions,
However position within these higher dimensions would not be measured via distance or time,
they would have their own, completely different, dimensional co-ordinates.
How causality within these higher dimensional realms would or could affect our 4D universe is too mind boggling for me to grasp...
In that time is in all likelihood no more than a human construction to effectively measure an arbitrary "distance" between events (see http://whatswaving.weebly.com/an-alt...elativity.html) the posit that there would be no time at the end of the universe should be interpreted as meaning there will be no more events nor anyone to observe the lack of events and in that sense only would constitute the end of time.

Really though the end of intelligent life would more accurately reflect the end of time whilst events continued to occur in the universe until perhaps further intelligent life evolved and time started again.

See my discussion on the nature of time http://whatswaving.weebly.com/an-alt...elativity.html

I have read with interest "A brief History of time". In my view theories postulating extra dimensions are unlikely to be valid and have yet to be evidenced. Anyone can set out a mathematical construct with arbitrary amounts of spacial dimensions (beyond the 3 that we observe) but mathematics does not evidence or prove reality. In my view the reason why string theory and other such theories appear so difficult to grasp is that they are solely (at this point of time) mathematical constructs. If an extra dimension is supposedly hidden by virtue of being too tightly wrapped up then the intersection of 3 imaginary lines of infinitesimal thickness will pass through the hidden dimension and collapse its existence as an extra dimension (see related discussion https://edge.org/conversation/theori...e-lisa-randall).

I have not come across any explanation as to why space and time would not exist in these conjectured extra dimensions. In the absence of any real evidence extra dimensions can only be imagined and as such it would be more rational to imagine that space does exist in another dimension by virtue of the fact that without having space for anything to occupy such a dimension cannot be occupied.
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Old Jul 25th 2015, 03:30 AM   #16
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Apologies to Dr Seuss

distance is a measure of the separation between thing 1 and thing 2
time is a measure of the separation between event 1 and event 2
why time and distance are so fundamentally different (for example 3 distance dimensions and 1 time) is obscure.

Note that both time AND distance cease at both the beginning and end of the universe.
Distance can not exist if these are no things which can be identified as being different things by reason of some form of separation which can be interpreted as distance.
If the mutual separations between things varies, then this introduces time.

If there is no separation (singularity) there is no distance and no time
If there are no things, there is no separation, thus no distance and no time.
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Old Jul 25th 2015, 06:44 AM   #17
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what are your views on my discussion http://whatswaving.weebly.com/an-alt...elativity.html Do you think that time is a human construct or that it exists as part of the fabric of the universe?

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Old Jul 25th 2015, 08:24 AM   #18
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It's Time Jonathan, but not as we know it.

It is both a part of the fabric of the universe and a human construct.
Time as we understand it in everyday life is a human construct
However this construct is founded on an underlying feature of the fabric of the universe.
As physicists have looked into it in detail they have found that there are distinct dichotomies between our ordinary human concept of time and what they find in their experiments.
PS
The link in your previous post did not work.
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Old Jul 25th 2015, 11:45 AM   #19
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Sorry about the link not working in my previous post, it is now repaired!
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