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#26 Otto Piechowski

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Posted 12 January 2020 - 12:29 AM

EJN, and any others who wish, please tell me about space-time.  Tell me what you believe to be important to know about space-time.  Tell me what you find interesting about space-time.  And share with me, please, those things you know about space-time which are clarifying idea-nuggets.  Thank you.  Otto



#27 Otto Piechowski

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Posted 12 January 2020 - 01:18 PM

For example, the statement that without space-time there is no universe; I would qualify that as a clarifying idea-nugget.

#28 llanitedave

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Posted 12 January 2020 - 02:51 PM

This is pretty much all there is to say about time.


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#29 B l a k S t a r

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Posted 12 January 2020 - 03:06 PM

I'm putting another log on the fire. 



#30 Tanglebones

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Posted 12 January 2020 - 05:17 PM

How very...timely.  I'm currently half-way through Carlo Rovelli's 'Order of Time' audiobook which discusses this in considerable depth.  As he builds to his conclusion, he discusses Aristotle's view (space and time do not exist independently of life), Newton's view (absolute space and absolute time do exist independently of life) and Einstein's view (space and time do not exist independently of each other, the are both aspects of spacetime). 

 

As EJN pointed out earlier in this thread, the equations of physics work regardless of the direction of time, the second law being an exception - but Rovelli discusses entropy extensively.  I'm struggling to recall his argument, but believe it was along the lines that “every time a difference is manifested between the past and the future, heat is involved. In every sequence of events that becomes absurd if projected backward, there is something that is heating up.  Even when you’re thinking: thinking produces heat in your head, and that is the only reason why your thoughts move from the past to the future."

 

That quote is an extract from The Order of Time Summary PDF which gives good overview of his book, which I'm very much enjoying as I commute.  It reminds me of a lecture I heard from Bob Berman, who addressed that ago old question whether or not a tree falling in the woods makes a sound if no living thing is there to hear it.  The answer being dependent on the definition of sound - momentary fluctuations in air pressure.  If no ear is present to translate those vibrations into nerve impulses, then the only 'sound' is that fluctuation in pressure.

 

Interesting stuff.  Makes people cross their eyes and look for someone else to talk to when I bring it up with friends. This was always a good Midwatch discussion tongue2.gif

 

- Stu


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#31 ColoHank

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Posted 12 January 2020 - 05:30 PM

I was able to photograph the passage of time in this two-minute exposure.  What more proof* would anyone need? 

 

*Dave, don't quibble with me about there being no such thing as scientific proof.

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#32 PXR-5

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Posted 12 January 2020 - 06:14 PM

My stomach is growling, therefore...



#33 EJN

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Posted 12 January 2020 - 08:16 PM

EJN, and any others who wish, please tell me about space-time.  Tell me what you believe to be important to know about space-time.  Tell me what you find interesting about space-time.  And share with me, please, those things you know about space-time which are clarifying idea-nuggets.  Thank you.  Otto

 

Rather than type a small novel, a good start is here:

 

https://en.wikipedia.../wiki/Spacetime

 

The most important points are that in the Newtonian view, space was fixed and absolute, as was time.

Spacetime is a dynamic entity, observers in different reference frames see time pass at different rates

(time dilation), and matter curves spacetime which manifests itself as gravity.

 

Also, when I say no spacetime = no universe, spacetime is the background on which all physics takes 

place. No spacetime means no particles, no fields, no matter & no energy. Which is the physicists

definition of nothing.



#34 TOMDEY

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Posted 12 January 2020 - 11:19 PM

HERE GOES somethings the conversation hasn't broached yet:

 

>Our immediate attention span, in the sense of sensing what we call ~the present~ seems to be a mere fraction of a second. Previous experiences we consider to be in the past and anticipated experiences we consider to be in the future.

>Our default purpose in life seems to be to try to make the future better, for ourselves and (distant second) for family and friends and (remote third) for mankind, the world and Universe.

>Our metrics of betterness are primal things like peace, comfort, nutrition, safety, pleasure, beauty, satisfaction, companionship, happiness...

>Our metrics of worseness are primal things like war, uneasiness, hunger, danger, pain, ugliness, longing, solitude, depression...

>Every waking moment seems focused on moving from worse to better, by taking action in the present to try to actualize that better future.

 

I believe that those few bullets pretty much explain all of human, animal and plant behaviors. From life-changing present moments like deciding to enroll in college to default trivia like putting one foot in front of the other... every one is a present action to help avoid worse future states; actualize better future states... probably. Accidentally touch a hot stove, and the immediate present focus is 100% desperation to retract the hand... occurring automatically, with barely conscious volition. Human, mouse or fly matters not; all three feel the same aversion and motivation to make the future state better.

 

But what is special about life? Isn't it just a matter of degree? If a fetus is alive, frenetically struggling to survive and flourish... then so the microbe, virus, amino acid, molecule, atom, quark, book, rock, planet, galaxy and Universe.

 

They are therefore all sentient, caring (to impulse to a better future state)... and that is the Prime Directive. We are alive because the Universe is. Us without It and It without Us would be the Null Set. And we think, therefore the Set is populated and motivated. And, like the Turing Machine... Our Destiny, after creating and experiencing all that can be --- will be the one and only action left undone... To Extinguish the Lights, having accomplished All. At that point, the Universe comes to the completely actualized state... and Time Stops. ~Q.E.D.~

 

Credit: The above concept (in different words) is extrapolated from the writings of Scott Adams.    Tom

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Edited by TOMDEY, 12 January 2020 - 11:22 PM.

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#35 llanitedave

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Posted 13 January 2020 - 10:07 AM

I was able to photograph the passage of time in this two-minute exposure.  What more proof* would anyone need? 

 

*Dave, don't quibble with me about there being no such thing as scientific proof.

Bbbb..bbbut, I WANT to quibble!  That's why I'm here!



#36 ColoHank

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Posted 13 January 2020 - 11:05 AM

Bbbb..bbbut, I WANT to quibble!  That's why I'm here!

Now I suppose you're going to try to convince me that, if my camera had been traveling away from the clock at the speed of light, the position of the hands in the image wouldn't have changed.   Where do you get such ideas?



#37 Otto Piechowski

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Posted 13 January 2020 - 02:51 PM

I am told that light travels at "the speed of light".  I have read enough popularized relativity that I have learned that as the motion of something approaches the speed of light, the time it takes to travel from one point to another asymptotically approaches zero.

 

For the photon of light, traveling at exactly the speed of light, the time it takes for that photon to travel from the 8 eight light years from the surface of Sirius A to earth is zero.

 

Now let us suppose that this photon was sentient.  Since it takes no time for it to travel from Sirius to the eyeball of an observer on earth; would that mean then, to this sentient-photon that the surface of Sirius and the eyeball of the observer on earth are in direct contact?

 

Otto


Edited by Otto Piechowski, 13 January 2020 - 03:06 PM.

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#38 TOMDEY

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Posted 14 January 2020 - 05:19 AM

I am told that light travels at "the speed of light".  I have read enough popularized relativity that I have learned that as the motion of something approaches the speed of light, the time it takes to travel from one point to another asymptotically approaches zero.

 

For the photon of light, traveling at exactly the speed of light, the time it takes for that photon to travel from the 8 eight light years from the surface of Sirius A to earth is zero.

 

Now let us suppose that this photon was sentient.  Since it takes no time for it to travel from Sirius to the eyeball of an observer on earth; would that mean then, to this sentient-photon that the surface of Sirius and the eyeball of the observer on earth are in direct contact?

 

Otto

Yes, exactly! And why photons don't "decay". Ironically, we can conclude that the Fountain of Youth is to stop time... in which case all experience ceases. So, it's a Catch-22. You need Entropy to enjoy the moment.

 

Father Time and the Grim Reaper are actually our friends. Without them, life would be moot, and the Universe would not be sentient.

~

"Father Time is the personification of time. In recent centuries he is usually depicted as an elderly bearded man, sometimes with wings, dressed in a robe and carrying a scythe and an hourglass or other timekeeping device (which represents time's constant one-way movement, and more generally and abstractly, entropy)."    Tom

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#39 llanitedave

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Posted 14 January 2020 - 03:20 PM

Now I suppose you're going to try to convince me that, if my camera had been traveling away from the clock at the speed of light, the position of the hands in the image wouldn't have changed.   Where do you get such ideas?

Well, the color of the image would have certainly changed.  To black.



#40 llanitedave

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Posted 14 January 2020 - 03:23 PM

I am told that light travels at "the speed of light".  I have read enough popularized relativity that I have learned that as the motion of something approaches the speed of light, the time it takes to travel from one point to another asymptotically approaches zero.

 

For the photon of light, traveling at exactly the speed of light, the time it takes for that photon to travel from the 8 eight light years from the surface of Sirius A to earth is zero.

 

Now let us suppose that this photon was sentient.  Since it takes no time for it to travel from Sirius to the eyeball of an observer on earth; would that mean then, to this sentient-photon that the surface of Sirius and the eyeball of the observer on earth are in direct contact?

 

Otto

 

Which brings up another interesting phenomenon.  Since the photon doesn't "see" time, and doesn't "see" distance, it has no idea of its own wavelength, so it can't tell what color it is.

 

Maybe it knows its energy state, though.



#41 BillP

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Posted 20 January 2020 - 05:23 PM

Perhaps an attempt to ask the opening question in another way, might be helpful.

 

Let us imagine our universe was devoid of life.  Would time exist in the universe?  Would space exist in the universe?

 

Otto

Of course they would not, and actually it may not even if life still exists!  This question is the same as if a tree falls in the forest does it make a sound (the answer is no btw as "sound" is a unique characterization for how a human mind perceives that physical phenomena based on the limited capabilities of the human ears -- the phenomena still happens but not "Sound" as sound only occurs in mind -- no mind, no sound).  Time and space are just  conceptualizations of the human mind as best understood by the capabilities of the human brain and input from its sensory organs.  It is how we, humans, perceive and understand what we are experiencing.  The reality of what we conceptualize as time and space with the limitations of the human mind may indeed be very much more complex and different.

 

It is like when one looks out the window at the back yard.  Is that reality that they are seeing?  Of course not.  Our seeing is limited to a subset of the full electromagnetic spectrum that is occurring in the back yard.  And even the portion of the spectrum we can see in the visible range is not comprehensive nor do we see all that is there.  As example, an animal with 4 color cones (tetrachromacy) instead of three will see a different version of reality than most humans as they gaze at the back yard as there will be about 100x more colors that they can perceive (100,000,000 vs 1,000,000).  It is probably fairly impossible to even simulate what a tetrachromat sees as would have to encode an image with false colors everywhere to indicate the missing 99 million colors the average human cannot see that the tetrachromat sees.  The average human does not have enough colors in its color pallet to do that!  So the greater capability of the brain/mind, the more correct understanding of everything and time, space, even mathematics may be completely different.

 

Bottom line is that all you have to do is think of it analogously to understand.  Assume you had the brain of a mouse instead of a human brain.  How you conceptualize existence would be very much limited compared to how a human brain can conceptualize given that it is so much more capable of a computational organ.  How would you understand time and space as a mouse?  Understanding that, ask yourself if you possessed a brain more capable than a human brain, as much more as a mouse is to a human, would your more capable conceptualization of the universe be limited for space and time as how the much less capable and cruder human brain understands things?  Of course not as you would have a much higher understanding of things and who know if our concepts of time and space would even be applicable to the understanding of that much more capable brain.


Edited by BillP, 20 January 2020 - 05:32 PM.


#42 BillP

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Posted 20 January 2020 - 05:43 PM

Now I suppose you're going to try to convince me that, if my camera had been traveling away from the clock at the speed of light, the position of the hands in the image wouldn't have changed.   Where do you get such ideas?

If your camera was moving at the speed of light, and the clock was not in that speedy reference frame, would not any picture you take be impossibly blurry since your best shutter speed might be 1/10,000 sec so you would have traveled 19 miles while the shutter was open?  Even if the clock was in the direction of travel or the direction away from travel it would be changing in size so would blur.  How big would the clock have to be for your camera lens to even resolve it at 19 miles away by the time the shutter closed?  I don't think you will be taking any worthwhile pictures, leave the camera home.


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#43 ColoHank

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Posted 20 January 2020 - 06:11 PM

To complicate matters further, the clock is hanging at the end of a hall which is nowhere near 19 miles long, and since the fastest shutter speed available to me is 1/8000 rather than 1/10000 second, the hall would actually have to be 23.25 miles in length.  Bummer.



#44 llanitedave

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Posted 20 January 2020 - 07:36 PM

To complicate matters further, the clock is hanging at the end of a hall which is nowhere near 19 miles long, and since the fastest shutter speed available to me is 1/8000 rather than 1/10000 second, the hall would actually have to be 23.25 miles in length.  Bummer.

Hank, if you can get us to the speed of light, I'll buy you a better camera...


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#45 ColoHank

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Posted 21 January 2020 - 04:57 AM

Hank, if you can get us to the speed of light, I'll buy you a better camera...

I'm working on it.  First, I'll upgrade to premium fuel in my RAV4 and see how that works.



#46 llanitedave

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Posted 21 January 2020 - 10:08 AM

I'm working on it.  First, I'll upgrade to premium fuel in my RAV4 and see how that works.

Hope you have the V-6.  With that 4 cylinder you'll never even get to medium relativistic velocities!



#47 ColoHank

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Posted 21 January 2020 - 10:37 AM

Hope you have the V-6.  With that 4 cylinder you'll never even get to medium relativistic velocities!

Darn!


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#48 CygnuS

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Posted 21 January 2020 - 11:56 AM

I haven't been following this thread but I did run across a quote this morning while flipping through an astronomy textbook. 

"It is said that an Eastern monarch once charged his wise men to invent him a sentence to be ever in view, and which should be true and appropriate in all times and situations. They presented him the words "And this, too, shall pass away." "

--Abraham Lincoln September 30, 1859


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#49 BillP

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Posted 21 January 2020 - 06:16 PM

Darn!

Connect a bottle of liquid oxygen to the air intake valve and fill the gas tank with kerosene.  It worked for the Saturn V, maybe it will get those 4 cylinders pumping faster.



#50 Keith Rivich

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Posted 21 January 2020 - 07:34 PM

Of course they would not, and actually it may not even if life still exists!  This question is the same as if a tree falls in the forest does it make a sound (the answer is no btw as "sound" is a unique characterization for how a human mind perceives that physical phenomena based on the limited capabilities of the human ears -- the phenomena still happens but not "Sound" as sound only occurs in mind -- no mind, no sound).  Time and space are just  conceptualizations of the human mind as best understood by the capabilities of the human brain and input from its sensory organs.  It is how we, humans, perceive and understand what we are experiencing.  The reality of what we conceptualize as time and space with the limitations of the human mind may indeed be very much more complex and different.

 

It is like when one looks out the window at the back yard.  Is that reality that they are seeing?  Of course not.  Our seeing is limited to a subset of the full electromagnetic spectrum that is occurring in the back yard.  And even the portion of the spectrum we can see in the visible range is not comprehensive nor do we see all that is there.  As example, an animal with 4 color cones (tetrachromacy) instead of three will see a different version of reality than most humans as they gaze at the back yard as there will be about 100x more colors that they can perceive (100,000,000 vs 1,000,000).  It is probably fairly impossible to even simulate what a tetrachromat sees as would have to encode an image with false colors everywhere to indicate the missing 99 million colors the average human cannot see that the tetrachromat sees.  The average human does not have enough colors in its color pallet to do that!  So the greater capability of the brain/mind, the more correct understanding of everything and time, space, even mathematics may be completely different.

 

Bottom line is that all you have to do is think of it analogously to understand.  Assume you had the brain of a mouse instead of a human brain.  How you conceptualize existence would be very much limited compared to how a human brain can conceptualize given that it is so much more capable of a computational organ.  How would you understand time and space as a mouse?  Understanding that, ask yourself if you possessed a brain more capable than a human brain, as much more as a mouse is to a human, would your more capable conceptualization of the universe be limited for space and time as how the much less capable and cruder human brain understands things?  Of course not as you would have a much higher understanding of things and who know if our concepts of time and space would even be applicable to the understanding of that much more capable brain.

There are sound waves within the sun. There is no life on the sun. Are the sound waves false?

 

And on looking into the backyard...

Blindfold yourself and run towards a tree. Reality will smack you in the face. 


Edited by Keith Rivich, 22 January 2020 - 10:07 AM.

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