Register | Sign In


Understanding through Discussion


EvC Forum active members: 65 (9164 total)
2 online now:
Newest Member: ChatGPT
Post Volume: Total: 916,902 Year: 4,159/9,624 Month: 1,030/974 Week: 357/286 Day: 0/13 Hour: 0/0


EvC Forum ⇒ Science Forums ⇒ Big Bang and Cosmology ⇒

Did the expansion rate of the universe exceed lightspeed?

Thread ▼ Details

Email This Thread
Newer Topic | Older Topic
  
Author Topic:   Did the expansion rate of the universe exceed lightspeed?
fallacycop
Member (Idle past 5550 days)
Posts: 692
From: Fortaleza-CE Brazil
Joined: 02-18-2006

Normal Thread Display
Message 5 of 86 (458662)
03-01-2008 1:29 PM 		Reply to: Message 3 by Percy
03-01-2008 11:28 AM

Cavediver will, I hope, correct me if I've got this wrong, but I take issue with the description that space expanded faster than the speed of light.
​
And you have good reasons to take issue with such a description.
The expanssion of the universe and the speed of light are measured with different physical units and, therefore, there is no meaningfull way to compare the two.
This message is a reply to:
 Message 3 by Percy, posted 03-01-2008 11:28 AM Percy has not replied
Replies to this message:
 Message 9 by cavediver, posted 03-01-2008 2:21 PM fallacycop has replied
  
fallacycop
Member (Idle past 5550 days)
Posts: 692
From: Fortaleza-CE Brazil
Joined: 02-18-2006

Normal Thread Display
Message 11 of 86 (458683)
03-01-2008 3:29 PM 		Reply to: Message 9 by cavediver
03-01-2008 2:21 PM

To make meaningfull statements in these scenarios, you had to stipulate some scale that was not intrinsicaly included in the original question. The scale chosen in the discussion with pecy was the plank scale. The scale chosen in the discussion with Chiroptera was the distance between two carefully chosen galaxies.
​
Edited by fallacycop, : grammar
This message is a reply to:
 Message 9 by cavediver, posted 03-01-2008 2:21 PM cavediver has replied
Replies to this message:
 Message 13 by cavediver, posted 03-01-2008 3:41 PM fallacycop has replied
  
fallacycop
Member (Idle past 5550 days)
Posts: 692
From: Fortaleza-CE Brazil
Joined: 02-18-2006

Normal Thread Display
Message 12 of 86 (458684)
03-01-2008 3:33 PM 		Reply to: Message 10 by Explorer
03-01-2008 2:40 PM

In some scenarios, depending on how much matter is present in the universe, the expansion may eventually halt and turn around into the Big Crunch.
This message is a reply to:
 Message 10 by Explorer, posted 03-01-2008 2:40 PM Explorer has not replied
  
fallacycop
Member (Idle past 5550 days)
Posts: 692
From: Fortaleza-CE Brazil
Joined: 02-18-2006

Normal Thread Display
Message 14 of 86 (458689)
03-01-2008 4:27 PM 		Reply to: Message 13 by cavediver
03-01-2008 3:41 PM

But then it is always possible (as long as there is some expansion at all) to find an scale large enough (unless the universe is finite) for the expansion to be fater then the speed of light.
​
How is that a meaningfull statement?
This message is a reply to:
 Message 13 by cavediver, posted 03-01-2008 3:41 PM cavediver has replied
Replies to this message:
 Message 15 by cavediver, posted 03-01-2008 5:11 PM fallacycop has replied
  
fallacycop
Member (Idle past 5550 days)
Posts: 692
From: Fortaleza-CE Brazil
Joined: 02-18-2006

Normal Thread Display
Message 16 of 86 (458709)
03-01-2008 6:05 PM 		Reply to: Message 15 by cavediver
03-01-2008 5:11 PM

1) two objects can have a perceived recession "velocity" caused by the expansion of space that is less than c.
​
2) this "velocity" can exceed c (though of course not be directly perceived) for two sufficiently separated objects.
​
3) This in no-way contradicts the usual limits of the speed of light nor any part of Special Relativity.
​
No part of 1), 2), and 3) is meaningless.
​
I agree. Those are meaningfull statements. The statement I was talking about was the one in the OP, though.
​
OP writes:
​
expansion rate of the universe at the moment of its birth was several times greater than the speed of light
​
The expansion rate of the universe is measured in Km/second/Megaparsecs (or some equivalent unit).
​
There is no way to compare that with the speed of light (in Km/s) and come out with the conclusion that it is several times greater.
This message is a reply to:
 Message 15 by cavediver, posted 03-01-2008 5:11 PM cavediver has not replied
Replies to this message:
 Message 53 by lyx2no, posted 03-06-2008 10:43 AM fallacycop has not replied
  
Date format: mm-dd-yyyy
Timezone: ET (US)
  
Newer Topic | Older Topic
Jump to:


Copyright 2001-2023 by EvC Forum, All Rights Reserved

™ Version 4.2
Innovative software from Qwixotic © 2024