Quick question about Light Speed communication

Can someone Answer my question. Light speed communication is the limit, of course everyone knows this. I was randomly thinking the other day. If we sent out a probe, and it live streamed from launch to lets say Alpha centauri wouldn't we get real time images from start to finish since there is never a cut from broadcast. Just a weird thought. I know I am wrong, but not sure why. I know it takes 1 year from one light year away to reach us, but if we are getting a constant feed how would that work.

a reply to: Crumbles

there would be delays in sending commands and seeing those commands take action

a reply to: choos

No commands. Just pure live video. Even though the bandwidth isn't realistic. Purely hypothetical.

a reply to: Crumbles
We would be receiving incrementally delayed video feed.

I know what you’re saying and it’s difficult to ‘envision’ but we still have to allow for the video to be sent to us over ever-increasing distance so we would experience ever-increasing delay.

The feed coming from one light year would still have to take one year to reach us.

We’d probably get a ‘glitch’ or something every now and then and miss out on a bit of footage. Either that or we wouldn’t really notice it as we got further and further ‘behind’.

Someone will put what I said into more technical/mathematical terms. Or outright blow my whole premise to bits.

a reply to: Crumbles

you would need commands, imagine without commands and then by the time it gets to alpha centauri the camera is pointed the wrong way.

a reply to: Crumbles

This is a very good question.
Now I can see why some may think that a single command can be used to send info to the recipient. But remember that send info will always have multiple commands being imputed at any given time. So unless this probe has a super computer that can do these commands onboard than chances of having little to no delay is doubtful.
Can it be done.....yes
Chances of seeing such a thing in our lifetime....fairly slim

Even with zero commands being sent. There would be delay.

Light speed means light speed. When the camera is one light year away, the signal will take one year to reach us. Meaning, one year delay.

a reply to: Breakthestreak

Pretty much this. You could figure out the change in the perceived time via a Lorenz Transformation (en.wikipedia.org...)
However given the most likely digital transfer of information via packets and the translation of said packets would result in the occasional skipped frame, or doubled frames, introducing errors. As the craft doing the traveling at such long distances would likely perceive less time as having passed due to Time Dilation (en.wikipedia.org...), the rate of packets being sent would be less than that of the observers due to the Relativistic Doppler Effect (en.wikipedia.org...).

As this experiment continued on the difference and error introduced would likely create all kinds of neat errors, however nothing we have currently sent probe wise has suffered to greatly due to this, as voyager 1 (en.wikipedia.org...) which has been traveling since 1977 has only experienced 1.6 seconds less time than we have, while being 16.4 light hours away.

Yeah, at one time the speed of sound was a barrier that could never be broken ... until someone did.

No one has yet answered the deeper question you are asking.

Light speed may not be a barrier at all, but nevertheless your question is still valid.

Assuming a feed without packets, that is a direct stream, one would have to assume that you would soon see the footage in slow motion.

Fascinating question.

P

originally posted by: Crumbles
Can someone Answer my question. Light speed communication is the limit, of course everyone knows this. I was randomly thinking the other day. If we sent out a probe, and it live streamed from launch to lets say Alpha centauri wouldn't we get real time images from start to finish since there is never a cut from broadcast. Just a weird thought. I know I am wrong, but not sure why. I know it takes 1 year from one light year away to reach us, but if we are getting a constant feed how would that work.

It depends on how fast the ship was traveling to Alpha Centauri. Let's say it was traveling the speed of the spaceraft that went to the moon or a little faster. It took the astronauts about 3 days to get to the moon and there was a delay of 1 second by the time they got to the moon. So even that video wasn't real time, it was already delayed by 1 second, though if that 1 second of lost time was spread out over 3 days on the trip to the moon, you'd hardly notice it. So that's how it would be if that craft continued on to alpha Centauri, every few days you would accumulate another 1 second delay. Given the trip would take over 100,000 years, those seconds would add up eventually.

If you send a faster ship, the delayed seconds will add up faster, but there will be a delay just the same, it won't be real time. A faster ship would also possibly have the frequencies red-shifted due to relativistic effects if it traveled at some significant fraction of the speed of light (time dilation meaning earthlings would see a clock on the fast ship running slower than a clock running on earth). So in that event, the ship could be broadcasting constantly and send 6 days of video according to the ship's clock, during the same time that clocks on earth advanced 7 days. So it could lose an entire day in a week, but it would have to be going very fast for that to happen, many times faster than any ship man has ever made.

For the people talking about delays in sending commands, I'm assuming the ship is robotically automated, so no commands need to be sent, it just broadcasts constantly.

There would be no "glitches" or skipped frames.

The signal itself would be simply red-shifted proportional speed of the spacecraft. This red-shift would cause a delay in the receiver.

You would be sending 30 frames per second, but it would take 2 seconds to receive them for example.

originally posted by: moebius
There would be no "glitches" or skipped frames.

The signal itself would be simply red-shifted proportional speed of the spacecraft. This red-shift would cause a delay in the receiver.

You would be sending 30 frames per second, but it would take 2 seconds to receive them for example.

Which is slow motion.

When the craft gets to where it is going, and while it would be delayed by four years, the slow motion effect would cease.

But yes, delayed by the time light would take to go from there to here.

P

there are particels known that are faster then lightspeed the so called MU-Mesonen just base an radio-system on it !

originally posted by: pheonix358
Which is slow motion.

When the craft gets to where it is going, and while it would be delayed by four years, the slow motion effect would cease.

But yes, delayed by the time light would take to go from there to here.

P

Yep. The delay would accumulate over time. A 10 years live stream would take 11 years to receive for a 1 lightyear travel distance.

Quantum communication is instantenous and wouldn't have any delays

a reply to: Crumbles

Wouldnt the stream have to speed up for the distance you traveled?

Folk saying that once the probe was one light year away, that there would be a one year delay, are missing an important point;

We'd have already been watching the stream for a year, hence, no delay.

*Waits to get shot down* lol

ETA, OK, I've just realised that this would only hold true if said probe was travelling at light speed,

*shoots self down*

a reply to: Crumbles

astroengineer.wordpress.com...

Here is a very interesting read for you. I had read an analysis of it, and it checked out from a tech position.

All,

Let's look at it a different way:

Say you sent a ship out with a camera 1 light year. The camera is recording the whole way. Once the ship reaches one light year out (equals one year to get there by the ship's perspective), the ship returns (one more year) and we look at the footage of the 1st trip.

I suspect:
- The film will be exactly 1 year in length.
- We will not get the film in 2 years even though the ship's time is a 2 year round trip.

I have no idea what the length of time before we received the film but it wouldn't be at 2 years.
- Wouldn't that ship become infinite in space and mass?
- Wouldn't that ship meet our future selves? (Future predetermined by this example?)
---- Thinking about it, the ship 'should' meet us at exactly 2 years just as he perceived but we would see him some many, many years later. It's backwards than what it would 'seem' as he would see the future us and we would see him at the same time he meets us. This is very confusing..

More questions:
- If light is traveling at the speed of 'light', wouldn't we see it moving slower but from the light's perspective it would be traveling at light speed?
- Why is light not infinite in space and mass? I know light doesn't have mass to begin with, supposedly but it does push or exert a force against mass.


This light speed stuff is very weird to understand.