Age of The Universe - Time vs Space

In summary, this concept is that 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.
  • #1
Buttonpusher
2
0
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?
 
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  • #2
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...
 
  • #3
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
 
  • #4
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, traveling 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.
 
  • #5
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
 
  • #6
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.
 
  • #7
dicerandom said:
...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.
 
  • #8
DaveC426913 said:
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".
 
  • #9
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.
 

1. What is the age of the universe?

The current estimated age of the universe is about 13.8 billion years old. This is based on measurements of the cosmic microwave background radiation and the expansion rate of the universe.

2. How do we measure the age of the universe?

Scientists measure the age of the universe by looking at the oldest objects in the universe, such as stars and galaxies. By studying the composition and distance of these objects, we can estimate how long they have been around.

3. How does the age of the universe relate to time and space?

The age of the universe is closely tied to the concepts of time and space. As the universe expands, time and space also expand. The age of the universe is therefore a measure of how much time has passed since the Big Bang and how much space the universe has occupied since then.

4. How has our understanding of the age of the universe changed over time?

Our understanding of the age of the universe has evolved over time as our technology and observational capabilities have improved. Early estimates placed the age of the universe at around 2 billion years, but with advancements in technology and new discoveries, we now have a more accurate estimate of 13.8 billion years.

5. How does the age of the universe impact our understanding of the universe?

The age of the universe is a crucial piece of information in understanding the history and evolution of the universe. It helps us understand how the universe has changed over time and how it will continue to evolve in the future. It also provides insights into the origins of the universe and the fundamental laws of physics that govern it.

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