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It's similar to how every sound you hear is of an event in the near past. Every thunderclap is caused by a past and distant lightning event. As a child, we'd se
by brianpan 4y ago
It's similar to how every sound you hear is of an event in the near past. Every thunderclap is caused by a past and distant lightning event. As a child, we'd see lightning and then count seconds waiting to hear the thunder (sound travels slower and takes longer to arrive than the light- about 2 seconds per mile).
If you're hearing thunder now, in a way, you're hearing an event in the past. The farther the thunder traveled, the farther into the past you are experiencing.
Across the expanse of space, you are not just hearing, but seeing into the past. The farther the light traveled, the farther into the past you are experiencing now.
- p1esk 4y agoYeah, so I’m older than the lightning. Am I also older than the sun? By this logic, I'm the newest thing in the universe, because it takes the shortest time for me to observe myself.
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- brianpan 4y agoI re-read the parent comment and I see why you're confused. It was awkwardly worded. "Older" and "younger" are confusing ways to put it. The fact is, simultaneous observations don't necessarily mean simultaneous events. If you hear 2 people shouting at the same time, but one person is very far away and one person is near, you can assume the person farther away actually shouted first. The reason this happens is the different delay across different distances. The distances have to be much greater to notice the difference with light compared to sound. But compared to the expanse of the universe, light actually travels quite slowly. If the sun disappeared, we wouldn't see it disappear on Earth for 8 minutes (that's how long it takes light to reach Earth). Essentially, we are seeing the Sun as it was 8 minutes in the past. The effect is even greater outside our solar system and even greater beyond our galaxy. We see stars and galaxies as they were, not just minutes but years and years in the past. Some stars that we see now have certainly already reached the end of their life, exploded into a supernova and collapsed. We just haven't seen it yet. The light from those events haven't reached us yet. Everything we see is of something as it was in the past. Even though we are seeing all the stars and galaxies simultaneously, the farther away it is, the farther into the past we are observing.
- p1esk 4y agoThe statement: "You are the oldest thing in the universe you can observe" has a very clear meaning - it literally means I am the oldest thing in the universe - out of all the things I can observe. This is obviously false - I'm less than 50 years old, and I can observe many much older things around me. Therefore, the statement is false, and no context or explanation can make it true, unless we start assigning completely new meanings to words like "oldest", "thing", "you" or "are". I was merely pointing this out. If the OP meant something else, they should have said something else. Those who try to explain how things work should use, demand and appreciate clear and logical language.