Does Time Dilation mean we are each alone in our own bubble?

[DarkloidNeos]

TL;DR

Are we each cosmically alone ?

[Moderator's note: Unacceptable reference deleted.]

I posted this on the physics sub of reddit but I'd ask here. I saw it on some video and when I googled it apparently there is truth to it in that the delay is nanoseconds, but to me that makes it sound like we are each in some space bubble away from everyone else and cannot contact them. How true is it or rather how much of a concern would it be?

 

[PeterDonis]

I saw it on some video and when I googled it

Please do not try to learn physics from "some video" and random google search results.

the delay is nanoseconds

Light travels at about one foot per nanosecond. So if you and I are, say, five feet apart from each other, we each are seeing the other as we were about five nanoseconds ago. That might be what was being referred to.

However, your thread title also mentioned time dilation. I'm not sure what "delay" has to do with time dilation.

to me that makes it sound like we are each in some space bubble away from everyone else and cannot contact them.

Um, isn't that obviously false?

Do you talk to people and get answers back? That's contact.

For that matter, you're posting here expecting to get a response. That's contact.

The fact that light has a finite speed certainly does not mean that you are disconnected. It just means the light signals that you exchange with the rest of the universe all the time, that bring information about the rest of the universe to you and carry information from you to the rest of the universe, travel at a finite speed. In your day to day life that's not even noticeable; the time scale of your perceptions is many orders of magnitude larger than nanoseconds. But people who deal with things happening on fast enough time scales or at large enough distances (such as the people who designed the GPS system that allows your smartphone to tell you where you are) have to take them into account.

 

[Dale]

Also, a few ns delay is irrelevant considering how slow speech, sound, nerve conduction, and neural processing are. A single syllable is about 100000000 ns. So the delay isn’t even a rounding error.

 

[DarkloidNeos]

But people who deal with things happening on fast enough time scales or at large enough distances (such as the people who designed the GPS system that allows your smartphone to tell you where you are) have to take them into account.

Wouldn't that apply to people on different parts of the globe?

 

[PeterDonis]

Wouldn't that apply to people on different parts of the globe?

The time it takes light to travel all the way around the Earth is about a tenth of a second. That's right about at the threshold of a time interval you can consciously perceive. But it's still swamped by other time delays in the machinery we use to communicate around the world.

If we want to look at cases of people communicating with each other, the farthest any humans have been from Earth was on the recent Artemis mission that went around the far side of the Moon. It took light signals almost two seconds to travel from Earth to the spacecraft, or vice versa, when it was at its furthest point (or close to four seconds for a round trip). That kind of delay is noticeable, yes--but it didn't stop them from communicating.

 

[AlexB23]

Are you talking about how since some people have traveled at different speeds or live in slightly different gravity, that some people are in the past and future relative to you? No dilation effects would be noticeable.

 

[PeterDonis]

since some people have traveled at different speeds ... that some people are in the past and future relative to you?

This is not really correct; it's an artifact of the way standard inertial frames work in relativity. The events you are talking about are spacelike separated; in that case, as far as actual physics is concerned they are neither in the past (because light signals from them haven't reached you yet) nor the future (because you can't affect them causally), but a third category which does not even exist in pre-relativity physics, but which relativity has taught us we have to accept.

 

[PeterDonis]

or live in slightly different gravity, that some people are in the past and future relative to you?

This is not correct either. The fact that, for example, people at different altitudes on Earth have slightly different natural "rates of time flow" due to gravitational time dilation does not mean that they are in one another's past or future.

 

[Dale]

Wouldn't that apply to people on different parts of the globe?

I regularly have meetings and communications with people around the globe. So the fact that I do contact them clearly indicates that I can contact them

 

[FactChecker]

Suppose a person is 5 feet from you. You might not be immediately affected by what he is doing now, but you are being affected by what he did 5 nanoseconds ago. That isn't a "bubble".
This has nothing to do with time dilation.

 

[PeroK]

TL;DR: Are we each cosmically alone ?

[Moderator's note: Unacceptable reference deleted.]

I posted this on the physics sub of reddit but I'd ask here. I saw it on some video and when I googled it apparently there is truth to it in that the delay is nanoseconds, but to me that makes it sound like we are each in some space bubble away from everyone else and cannot contact them. How true is it or rather how much of a concern would it be?

If you find yourself alone on a Saturday night, you cannot blame the laws of physics.

 

[DarkloidNeos]

The time it takes light to travel all the way around the Earth is about a tenth of a second. That's right about at the threshold of a time interval you can consciously perceive. But it's still swamped by other time delays in the machinery we use to communicate around the world.

Right but this was a remark I got from the reddit thread I asked it on:

"Every point in spacetime is affected by only what is happening at that point, yes. You are perpetually cut off from being in actual contact with anything except at your exact location in spacetime.

This doesn’t mean you live in your own private universe, just that nothing can affect you instantaneously. The effects of causes must travel to you first. And those effects cannot ever travel to faster than the speed of light."

"You are separated from everything around you by about 3ns per meter. When you look at something 100m away, you're seeing it as it was 300ns ago."

This reminds me also of the processing delay of the brain. But none of this means we are alone right?

 

[Dale]

We already answered that.

Since we are just going around in circles we will close this thread here. A Reddit thread is not a valid reference, and engaging in debate-by-proxy is entirely pointless.