EvC Forum: Cosmological Q&A

Email This Thread

Newer Topic | Older Topic

Author

Topic: Cosmological Q&A

New Cat's Eye

Inactive Member

Normal Thread Display

Message 6 of 11 (472741)
06-24-2008 3:08 PM

Reply to: Message 4 by Agobot
06-24-2008 1:58 PM

Re: Redshift -

BBT claims that galaxies and stars are not moving but space between them expands/grows. If they are not moving why do scientists think that non-moving objects should cause a redshift?

As the space between them expands, the distance between them grows. As the distance between them grows, the light traveling across that distance is red-shifted.

This message is a reply to:
	Message 4 by Agobot, posted 06-24-2008 1:58 PM		Agobot has not replied

New Cat's Eye

Inactive Member

Normal Thread Display

Message 8 of 11 (472760)
06-24-2008 4:06 PM

Reply to: Message 7 by AshsZ
06-24-2008 3:45 PM

minor quibble

When we say that an object is 30 million light years away from us, we are saying that they are 30 million light year MILES away from us because that is the time it takes the light from those objects to cover that distance.

There's no such thing as "Light Year Miles".

A light year is a unit of length. It is the distance light travels in one year. 1 light year = 5,878,625,373,183.61 international miles (source).

This message is a reply to:
	Message 7 by AshsZ, posted 06-24-2008 3:45 PM		AshsZ has replied

Replies to this message:
	Message 9 by AshsZ, posted 06-24-2008 4:58 PM		New Cat's Eye has replied

New Cat's Eye

Inactive Member

Normal Thread Display

Message 10 of 11 (472780)
06-24-2008 5:15 PM

Reply to: Message 9 by AshsZ
06-24-2008 4:58 PM

Re: minor quibble

I think we are saying the same thing.

A light year is the distance light will travel over a year. So when I say "light year miles" and quantify that with the "30 million", the object is 30 million times 5,878,625,373,183.61 miles.

You'd be saying just as much by saying 30 million light years.

Do you also use the phrase "500 kilometer miles" when referring 311 miles?

Or would you call 311 miles --> 5.3x10^-11 light year miles?

So when you look at an object that is 30 million light years away from you, you are seeing what it looked like 30 million years ago. This object is also 176358761195508300000 miles away (30 million times 5,878,625,373,183.61).

Am I missing something?

If the object is moving away from us, then it wasn't as far away 30 million years ago when the light that is finally reaching us left it as it is now. The distance to it now is farther than it was 30 million years ago.

This message is a reply to:
	Message 9 by AshsZ, posted 06-24-2008 4:58 PM		AshsZ has not replied

Date format: mm-dd-yyyy

Timezone: ET (US)

Newer Topic | Older Topic

Do Nothing Button

2 online now:	PaulK, Phat
Newest Member:	ChatGPT
Post Volume:	Total: 916,911 Year: 4,168/9,624 Month: 1,039/974 Week: 366/286 Day: 9/13 Hour: 1/1