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Author Topic:   Astronomers See Evidence of Something Unexpected in the Universe
NoNukes
Inactive Member


Message 31 of 86 (829367)
03-06-2018 12:44 PM
Reply to: Message 29 by Taq
03-06-2018 11:20 AM


GR does posit that the speed of light is the same for all observers in all reference frames.

All inertial reference frames, actually.


Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)

"Give me your tired, your poor, your huddled masses yearning to breathe free, the wretched refuse of your teeming shore. Send these, the homeless, tempest-tossed to me, I lift my lamp beside the golden door!

We got a thousand points of light for the homeless man. We've got a kinder, gentler, machine gun hand. Neil Young, Rockin' in the Free World.

Worrying about the "browning of America" is not racism. -- Faith

I hate you all, you hate me -- Faith


This message is a reply to:
 Message 29 by Taq, posted 03-06-2018 11:20 AM Taq has not yet responded

  
nwr
Member
Posts: 5583
From: Geneva, Illinois
Joined: 08-08-2005


Message 32 of 86 (829368)
03-06-2018 12:50 PM
Reply to: Message 27 by Son Goku
03-06-2018 4:56 AM


Unless I am missing the point General Relativity actually assumes that standard clocks and rulers don't exist and then makes predictions for what we should see here based on that.

Yes, I agree with that.

Thus it could be that local clocks and rulers show that the cosmos appears to be expanding locally, yet there is no meaning of "expanding" that applies to the cosmos as a whole.

To be clear: I'm suggesting everywhere in the cosmos, local observers might see the local appearance of expanding. And yet that does not make "expanding" a meaningful term to apply to the cosmos as a whole.


Fundamentalism - the anti-American, anti-Christian branch of American Christianity

This message is a reply to:
 Message 27 by Son Goku, posted 03-06-2018 4:56 AM Son Goku has not yet responded

Replies to this message:
 Message 37 by Taq, posted 03-06-2018 5:16 PM nwr has responded

  
NoNukes
Inactive Member


Message 33 of 86 (829370)
03-06-2018 12:53 PM
Reply to: Message 28 by Percy
03-06-2018 8:05 AM


NoNukes makes the point that Creation was focused on time, but Creation wasn't capable of generalizing and made his points with examples. Time was his initial example, but he moved on to say we couldn't know relativity behaved the same in deep space as it does here (Message 682), and he said we couldn't know the speed of light out there is the same as here (Message 703). He used examples rather than generalizations, but he obviously believed we can't know whether scientific laws out there are the same as here.

All of creation's conclusions were based on time not behaving the same as it does here. For example, he said that we could not know how far light traveled because we did not know the rate of time passage in those distant places. He may well have believed more than that, but at this point, you appear to be putting ideas into the rather small place that was creation's thinking on this topic.

Despite the differences, I would respond to both nwr and creation in pretty much the same way Taq has already answered. We have at least some evidence for the position that our formulation of physics is applicable in distant space, while the opposing position is just denial and supposition.


Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)

"Give me your tired, your poor, your huddled masses yearning to breathe free, the wretched refuse of your teeming shore. Send these, the homeless, tempest-tossed to me, I lift my lamp beside the golden door!

We got a thousand points of light for the homeless man. We've got a kinder, gentler, machine gun hand. Neil Young, Rockin' in the Free World.

Worrying about the "browning of America" is not racism. -- Faith

I hate you all, you hate me -- Faith


This message is a reply to:
 Message 28 by Percy, posted 03-06-2018 8:05 AM Percy has acknowledged this reply

Replies to this message:
 Message 34 by ICANT, posted 03-06-2018 2:43 PM NoNukes has responded

  
ICANT
Member
Posts: 5971
From: SSC
Joined: 03-12-2007


Message 34 of 86 (829394)
03-06-2018 2:43 PM
Reply to: Message 33 by NoNukes
03-06-2018 12:53 PM


Time
Hi NoNukes,

NoNukes writes:

All of creation's conclusions were based on time not behaving the same as it does here.

Just one of my foolish thoughts but I thought it was a given that time in space does not behave the same as it does on earth.

In one of the twin's taking a journey into space and returning that twin is supposed to have aged a lot less than the twin on earth.

So wouldn't that mean that the speed something traveled in space would change time compared to here on earth.

Just asking.

God Bless,


"John 5:39 (KJS) Search the scriptures; for in them ye think ye have eternal life: and they are they which testify of me."

This message is a reply to:
 Message 33 by NoNukes, posted 03-06-2018 12:53 PM NoNukes has responded

Replies to this message:
 Message 35 by NoNukes, posted 03-06-2018 3:07 PM ICANT has not yet responded
 Message 39 by Taq, posted 03-06-2018 5:28 PM ICANT has not yet responded

    
NoNukes
Inactive Member


(3)
Message 35 of 86 (829400)
03-06-2018 3:07 PM
Reply to: Message 34 by ICANT
03-06-2018 2:43 PM


Re: Time
Just one of my foolish thoughts but I thought it was a given that time in space does not behave the same as it does on earth.

In one of the twin's taking a journey into space and returning that twin is supposed to have aged a lot less than the twin on earth.

You are confused and if you are looking for my help, you can stay confused. I am not going to discuss special relativity with you again. You are the one adult on earth with whom I refuse to have a dialog about physics.

Edited by NoNukes, : No reason given.

Edited by NoNukes, : No reason given.


Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)

"Give me your tired, your poor, your huddled masses yearning to breathe free, the wretched refuse of your teeming shore. Send these, the homeless, tempest-tossed to me, I lift my lamp beside the golden door!

We got a thousand points of light for the homeless man. We've got a kinder, gentler, machine gun hand. Neil Young, Rockin' in the Free World.

Worrying about the "browning of America" is not racism. -- Faith

I hate you all, you hate me -- Faith


This message is a reply to:
 Message 34 by ICANT, posted 03-06-2018 2:43 PM ICANT has not yet responded

  
Son Goku
Member
Posts: 1115
From: Ireland
Joined: 07-16-2005
Member Rating: 4.0


Message 36 of 86 (829405)
03-06-2018 4:14 PM
Reply to: Message 29 by Taq
03-06-2018 11:20 AM


Special Relativity posits that all inertial observers agree on the speed of light.

General Relativity, lacking global inertial observers (i.e in general there are no inertial frames) doesn't even posit that. The speed of light will be observer dependent.


This message is a reply to:
 Message 29 by Taq, posted 03-06-2018 11:20 AM Taq has responded

Replies to this message:
 Message 38 by Taq, posted 03-06-2018 5:20 PM Son Goku has responded

  
Taq
Member
Posts: 7575
Joined: 03-06-2009
Member Rating: 3.6


Message 37 of 86 (829406)
03-06-2018 5:16 PM
Reply to: Message 32 by nwr
03-06-2018 12:50 PM


nwr writes:

Thus it could be that local clocks and rulers show that the cosmos appears to be expanding locally, yet there is no meaning of "expanding" that applies to the cosmos as a whole.

If the expansion was local then all galaxies outside of the local area would be redshifted by the same amount, but they aren't. More distant galaxies are redshifted more strongly than nearby galaxies, and there isn't a point in the cosmos where redshift caps out. The only explanation that makes sense is that the entire length of space between us and all galaxies is expanding at the same rate per unit of length.


This message is a reply to:
 Message 32 by nwr, posted 03-06-2018 12:50 PM nwr has responded

Replies to this message:
 Message 41 by nwr, posted 03-06-2018 8:32 PM Taq has responded

  
Taq
Member
Posts: 7575
Joined: 03-06-2009
Member Rating: 3.6


Message 38 of 86 (829408)
03-06-2018 5:20 PM
Reply to: Message 36 by Son Goku
03-06-2018 4:14 PM


Son Goku writes:

Special Relativity posits that all inertial observers agree on the speed of light.
General Relativity, lacking global inertial observers (i.e in general there are no inertial frames) doesn't even posit that. The speed of light will be observer dependent.

Could you describe a situation where the speed of light is observer dependent within GR?


This message is a reply to:
 Message 36 by Son Goku, posted 03-06-2018 4:14 PM Son Goku has responded

Replies to this message:
 Message 40 by Son Goku, posted 03-06-2018 8:09 PM Taq has responded

  
Taq
Member
Posts: 7575
Joined: 03-06-2009
Member Rating: 3.6


Message 39 of 86 (829409)
03-06-2018 5:28 PM
Reply to: Message 34 by ICANT
03-06-2018 2:43 PM


Re: Time
ICANT writes:

Just one of my foolish thoughts but I thought it was a given that time in space does not behave the same as it does on earth.

In one of the twin's taking a journey into space and returning that twin is supposed to have aged a lot less than the twin on earth.

So wouldn't that mean that the speed something traveled in space would change time compared to here on earth.

Clocks do tick at different rates with respect to gravity and relative velocity. The famous Hafele-Keating experiment used atomic clocks on jetliners to determine that clocks tick faster further away from the Earth's center of gravity. In modern times we observe that the clocks on GPS satellites tick at a higher rate than those same clocks on the surface of the Earth. However, the differences are in the nanosecond range, so not that significant.

Cosmologically, you don't see significant time dilation until you get to the highest redshifted galaxies. In these cases, scientists have seen time dilation in the form of type Ia supernovae taking longer to brighten and dim compared to the same supernovae in nearer and less redshifted galaxies. Within our own galaxy, movements are dominated by gravity so any redshift we see is due to movement through space instead of expansion of space itself.


This message is a reply to:
 Message 34 by ICANT, posted 03-06-2018 2:43 PM ICANT has not yet responded

  
Son Goku
Member
Posts: 1115
From: Ireland
Joined: 07-16-2005
Member Rating: 4.0


Message 40 of 86 (829413)
03-06-2018 8:09 PM
Reply to: Message 38 by Taq
03-06-2018 5:20 PM


I don't know how much detail you want (actual calculations?), but if you shine light on a mirror above the event horizon of a black hole and time the return of the beam and the distance, you won't get the usual speed of light.
This message is a reply to:
 Message 38 by Taq, posted 03-06-2018 5:20 PM Taq has responded

Replies to this message:
 Message 43 by Taq, posted 03-07-2018 3:37 PM Son Goku has responded

  
nwr
Member
Posts: 5583
From: Geneva, Illinois
Joined: 08-08-2005


Message 41 of 86 (829416)
03-06-2018 8:32 PM
Reply to: Message 37 by Taq
03-06-2018 5:16 PM


If the expansion was local then all galaxies outside of the local area would be redshifted by the same amount, but they aren't.

Sigh!

This is still a complete misunderstanding of what I have been saying.


Fundamentalism - the anti-American, anti-Christian branch of American Christianity

This message is a reply to:
 Message 37 by Taq, posted 03-06-2018 5:16 PM Taq has responded

Replies to this message:
 Message 42 by Taq, posted 03-07-2018 1:14 PM nwr has responded

  
Taq
Member
Posts: 7575
Joined: 03-06-2009
Member Rating: 3.6


Message 42 of 86 (829442)
03-07-2018 1:14 PM
Reply to: Message 41 by nwr
03-06-2018 8:32 PM


nwr writes:

This is still a complete misunderstanding of what I have been saying.

You can hardly blame us if you then refuse to clear up any misunderstandings.


This message is a reply to:
 Message 41 by nwr, posted 03-06-2018 8:32 PM nwr has responded

Replies to this message:
 Message 46 by nwr, posted 03-08-2018 11:27 PM Taq has responded

  
Taq
Member
Posts: 7575
Joined: 03-06-2009
Member Rating: 3.6


(1)
Message 43 of 86 (829449)
03-07-2018 3:37 PM
Reply to: Message 40 by Son Goku
03-06-2018 8:09 PM


Son Goku writes:

I don't know how much detail you want (actual calculations?), but if you shine light on a mirror above the event horizon of a black hole and time the return of the beam and the distance, you won't get the usual speed of light.

I would assume that this would also be true for a laser beam shot from space and bouncing off of a mirror 500 miles below on the face of the Earth (but obviously with less of a difference than with a black hole)?


This message is a reply to:
 Message 40 by Son Goku, posted 03-06-2018 8:09 PM Son Goku has responded

Replies to this message:
 Message 44 by Son Goku, posted 03-07-2018 5:56 PM Taq has not yet responded

  
Son Goku
Member
Posts: 1115
From: Ireland
Joined: 07-16-2005
Member Rating: 4.0


(1)
Message 44 of 86 (829465)
03-07-2018 5:56 PM
Reply to: Message 43 by Taq
03-07-2018 3:37 PM


Yes indeed, the black hole is a dramatic exaggeration where it would be obvious to a human, but it'd be true above the Earth.

For spherical gravitational fields the speed would be:

where c is the usual speed with no gravity around and the speed in the presence of gravity. M the Mass of the body, G is Newton's Constant and r is the radius of the observer.

For the case you mentioned that results in light being less than a m/s slower.

Edited by Son Goku, : No reason given.


This message is a reply to:
 Message 43 by Taq, posted 03-07-2018 3:37 PM Taq has not yet responded

  
NoNukes
Inactive Member


Message 45 of 86 (829468)
03-07-2018 7:47 PM
Reply to: Message 7 by nwr
02-26-2018 8:47 PM


Talk of "the expanding universe" implicitly assumes that there is a yardstick (for measuring distance) which can be used throughout the cosmos and for all time. I cannot see any reason to believe that. We use a local yardstick defined in terms of local features. And it may well be that every location can have a local yardstick. But I cannot see any certainty that we can put these together to have a cosmos-wide yardstick. It might be that there are local distance functions at every location, but no single distance function that can be used across the entire cosmos. And there could be similar issues with the measurement of time and with the measurement of other physical properties.

The map of distance to red-shift is empirically derived and is checked against phenomena that do not require measuring the travel of light. In addition, in those few situations where we can use the speed of light to make a measurement, such as SN 1987a, we have confirmation using an additional method.

Against all that we have your proposal of a completely different universe for which we have no confirming science whatsoever. Why do you believe in your model over those of others?


Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)

"Give me your tired, your poor, your huddled masses yearning to breathe free, the wretched refuse of your teeming shore. Send these, the homeless, tempest-tossed to me, I lift my lamp beside the golden door!

We got a thousand points of light for the homeless man. We've got a kinder, gentler, machine gun hand. Neil Young, Rockin' in the Free World.

Worrying about the "browning of America" is not racism. -- Faith

I hate you all, you hate me -- Faith


This message is a reply to:
 Message 7 by nwr, posted 02-26-2018 8:47 PM nwr has acknowledged this reply

  
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