Register to reply

Age of The Universe - Time vs Space

by Buttonpusher
Tags: space, time, universe
Share this thread:
Buttonpusher
#1
Feb22-06, 01:57 AM
P: 2
I have long wondered about this. When light takes x number of billion years to reach earth, we judge that the star emitting the light is x number of billions years old. I cannot understand that the star would be the same age as the distance it is away from us. If I was riding a spaceship at the head of that beam of light, I would not age the same as people, i.e.time, on earth. I would, in fact, be much yonger in years than the distance in light years traveled. Is this right? If it is, then would we not have to recalulate the age of the universe using this type of equation?
Phys.Org News Partner Space news on Phys.org
Planetary Society hopes tiny satellite sets sail above Earth
Tidal forces gave moon its shape, according to new analysis
Young binary star system may form planets with weird and wild orbits
Pengwuino
#2
Feb22-06, 02:33 AM
PF Gold
Pengwuino's Avatar
P: 7,120
Well your first assumption is wrong. We get light from the sun in 5 minutes but that doesn't mean the sun is 5 minutes old...
chroot
#3
Feb22-06, 03:21 AM
Emeritus
Sci Advisor
PF Gold
chroot's Avatar
P: 10,428
It's 8 minutes, Pengwuino, but you're right, there's a misunderstanding here.

Properly phrased, the concept is this: If you're looking at an object that is a billion light-years away, you're seeing light that was emitted a billion years ago. You are, therefore, seeing the object as it was a billion years ago.

The age of the object -- the time since it formed -- has nothing to do with it.

- Warren

Chronos
#4
Feb23-06, 12:38 AM
Sci Advisor
PF Gold
Chronos's Avatar
P: 9,387
Age of The Universe - Time vs Space

Hi Buttonpusher! Welcome to PF. Plenty of brain bending concepts are regularly tossed around here. Chroot gave a very nice answer. Hopefully, I can expand on it a bit. If you were a photon, travelling at the speed of light, your wristwatch would indicate you had traversed the distance between your home star and earth in no time flat. You would look exactly like you did the moment you began your journey, aside from some bending and stretching effects.
Buttonpusher
#5
Mar3-06, 12:41 PM
P: 2
I thank you people for enlightening me on this subject. I understand now that when traveling at the speed at light, I get there quicker in time while the distance traveled remains the same.
_______________
Do not worry about your difficulties in Mathematics. I can assure you mine are still greater. - Albert Einstein
dicerandom
#6
Mar3-06, 01:31 PM
P: 308
Actually, I believe that if you're going to use the "zero time" picture of light you must also have "zero distance". Physically this should be reasonable since if no time passed you didn't go anywhere.

Speaking more geometrically, as a velocity approaches c relative to some inertial observer both the time and space axes rotate up towards the 45 degree line on a Minkowski diagram, in the limit as v approaches c all of the events in space-time approach one single event.
DaveC426913
#7
Mar3-06, 01:56 PM
DaveC426913's Avatar
P: 15,319
Quote Quote by dicerandom
...Speaking more geometrically, as a velocity approaches c relative to some inertial observer both the time and space axes rotate up towards the 45 degree line on a Minkowski diagram, in the limit as v approaches c all of the events in space-time approach one single event...
What on Earth does this have to do with the OP's question??? (Sorry to pick on you Dicey, you're one among many). These answers are worse than no answer at all, as they actually confuse the matter.
dicerandom
#8
Mar3-06, 03:37 PM
P: 308
Quote Quote by DaveC426913
What on Earth does this have to do with the OP's question??? (Sorry to pick on you Dicey, you're one among many). These answers are worse than no answer at all, as they actually confuse the matter.
The OP's original question had already been answered, I was responding to his comment that "when traveling at the speed at light, I get there quicker in time while the distance traveled remains the same".
Chronos
#9
Mar4-06, 01:09 AM
Sci Advisor
PF Gold
Chronos's Avatar
P: 9,387
Under GR, traveling at the speed of light completely negates any consideration of distance. A photon, unless intercepted, traverses the entire universe in no time whatsover [by her watch]. Study the Einstein equations and this will become apparent.


Register to reply

Related Discussions
Do time and space exist within the universe? Special & General Relativity 22
Is time, inside an event horizon, time-like or space-like? Special & General Relativity 34
Can You Imagine a Universe Without Space and Time? General Discussion 64