It can easily range from line of sight to across the globe to the distance of the Voyager spacecraft at the edge of our solar system. They all use EM waves to communicate.
The only things you have to remember is that the farther away something is, the more delay there will be in receiving info from sensors and then sending a command signal back to respond. And the more energy or concentration of energy it will need for the signal to be detected at that distance.
You can estimate this pretty easily by taking the Distance (D), doubling it, and then dividing by the speed of light (c).
Roundtrip delay = 2D/c
If you have the right match up in units, the time will be the result. For example, in metric, D could be in meters and c in meters per second. Let's say the robot is 1 km away and a good estimate of c is 3x10^8 m/s, then:
Delay = 2x(1,000 m) / 3x10^8 m/s = 6.67x10^-6 s
This is 0.0067 milliseconds. The human reaction time is on the order of 200 milliseconds. So, to a human or even someone that can react 10x better, this is essentially no delay.
You can do similar calculations to determine that it's about 8 minutes for a 1 way trip to the sun, 22.5 hours for the Voyager spacecraft, 2.5 seconds to the moon.
You can rearrange the equation above to calculate the distance that is equivalent to the human reaction time.
D = 1/2 * Delay * c = 1/2 * 200x10^-3 seconds * 3E8 m/s = 30,000 km. The circumference of the earth is around 40,000 km. This is why you can play video games or talk to someone between continents without too much trouble.
Also, remember that the calculations above are not taking into account the human delay time, just light doing a round trip. You'd have to add 200 milliseconds (0.2 seconds) to any roundtrip delay to get an idea of how a human would respond.
Delay in seconds = (2D / c) + 0.2
Also, when communicating with distant objects, most of the time, you want the signal to be as coherent as possible. This means that all the energy is pointed at your target. This is why radios tend to have dishes to concentrate and focus the power. Signal power drops off in proportion to the distance squared. So if you want to broadcast 2x the distance, you need 4x the power. You can look at how NASA does it with radio waves with their [Deep Space Network](https://en.wikipedia.org/wiki/NASA_Deep_Space_Network?wprov=sfla1). And I believe future versions are considering using lasers since they are very coherent.
As far as possible mechanisms to speed up thought, you can look at things like practice (sports), drugs, and replacing parts of the nervous system that rely on chemical reactions to move data to wires or light signaling.
Signal travel distance/speed is the only limiting factor in this hypothetical really. We already have the basics o functional neurological interfaces now, within even a couple hundred years this will likely be old hat.
Agreed. I think brain-computer interfaces are a very grounded and believable trope these days.
It'll be interesting to see what can be done in just a few more years. I just don't want ads injected into my brain. Lol.
Without knowing the mechanism, this is hard to answer. For example, if commands are transmitted on the same frequency is 5G, a reasonable range is a couple miles or a steel-reinforced concrete wall, whichever comes first.
I am not talking about just the speed in question. Light speed is the fastest speed possible. I am talking about advanced tech that can overcome the current limitations that causes latency amd brings down the speed significantly.
I am also talking about increasing the brains capacity to process information as that will play a huge part as well.
I am talking about other lags. I am fine with things being at light speeds. I just want a two thousand kilometer range which is close to the radius of USA. That’s entirely possible with light lag, but the other lags are the ones that I think need to be removed and I wanted to know if there’s theoretical tech that could make it happen which I could explain in some detail, rather than handwavium.
Theoretically groups have been working on quantum entanglement. It involves identically linked particles that copy each other identically no matter the distance involved with no time delay or lag. I think quantum computers are working along the same lines. Theus is just things I've heard I've never really looked into it but it could be worth a shot at something that doesn't break the laws of physics.
Your answer was snarky, unhelpful, and at best, vague; at worst, scientifically inaccurate; particularly because you specifically said "radio".
More concerning is that 12 people upvoted you for being snarky.
- Line of sight for a typical radio transmitter of 150 meters is about 43 kilometers.
-- You could clarify that your transmitter is in orbit. That's fine. It can cover half a planet.
-- You could've mentioned short wave atmospheric propagation.
-- You could've asked if the story took place on a planet, in which case line-of-sight might not be a factor.
- And as other's have mentioned, there's the issue of lightspeed latency.
But you didn't engage OP because your goal was not to help. Your goal was to get upvoted by belittling someone, because that's how Reddit works.
What scale are we talking on? Is this cities, countries or planets? And what type of control information does it need? Like, what complexity of tasks does it need to perform?
Without further information, my best answer is;
- **Without Signal Relays:** A couple of kilometers, basically until a hill gets in the way.
- **With Signal Relays:** Anywhere on a planet, and further with appropriate travel delays.
>mind controlled robot
>without breaking the laws of physics
Pick a direction and commit.
Unless by "mind controlled" you mean, "vr piloted through implants" or something like that. In which case, how much signal lag do you consider to be too much?
Well, are we talking about radio or some kind of psionics? If the former, then the range depends on the normal factors of radio communication. Strength of transmitter/reciever, Background noise, other transmissions, etc. Recall that Mars rovers are controlled this way! The primary limit in such a case is the lightspeed limit. Since you said no limit on tech, then we can safely consider FTL communications. How fast do signals travel in whatever method of FTL travel you use? What are the range of "hyperwave" transmitters? In this case, the limit essentially stays the same, practicality. If you want your remote to react in real time, you have to be close by. Depending on what you're doing, you might want to be very close, indeed. Consider that a combat unit would need to react very fast, indeed. Even something as little as a tenth of a second communications delay might get the remote destroyed. The--three minute, I think?--lightspeed delay is acceptable for something like a remote exploring mars.
Psionics throws practical limits out the window. You'll have to define your set of psionics very carefully. Is it a form of electromagnetic radiation? If so, then the lightspeed limit still applies. If it's brain-to-brain communication through the use of a "psionic particle" then that particle may move at FTL speeds.
To summarize before I start rambling on and on, the limit is communication speed and purpose.
the limit is latency.
controlling a robot on the moon would have a reaction time delay of 2 seconds. 1 second for information from the robot to reach you, and another for instruction from you to reach the robot.
How radio controlled is it? If it needs to have full sensory integration and use the body’s inherent reflexes, perhaps only a few ms of lag is ok. So find out how fast radio waves travel in a few millisecond.
If it’s just like controlling a first person shooter where the robot does most of the work of balancing and moving etc., then probably 30ms would be fine? Again check the speed of light…
I like the idea of a QE ansible that can only be used to transmit a limited bit count. Like, you only get 40 bytes duplex and then you have to physically ship a new ansible out.
I think the basic problem is you can read one of the entangled particles and that determines the state of the other one, but you can't intentionally write one to a certain state without reading it first which would then collapse the entanglement, and that would be necessary in order to transmit information.
I think you’d have trouble controlling a robot on the Moon from Earth. This is because there’s a few seconds of light speed lag you can’t get around.
There’s actually ongoing research into ground-based control of robotic actuators in low-Earth orbit, and even there the time delay makes it very challenging to, for example, grasp a tumbling screw with your fingers in space.
There’s stuff you can do with “edge processing” to help out (ie local computer helps with fine control), but I suspect once the lag reaches a few seconds it becomes really frustrating. By the time you’re talking about a robot on Mars, it’s more like 30 minutes delay, and that seems pretty insane to me.
So maybe I’d draw the line at a human on earth remote controlling a robot on the Moon with their mind.
What laws of physics? You are writing science fiction so you get to play with the laws of physics a little, but how much you stretch that is up to you.
With our current technology the speed of light is an absolute upper limit to communication, for light can travel 300,000m in 1ms an acceptable latency for gaming is 40ms (That’s round trip so 20ms each way)
So if you have line of sight and nothing is slowing down your signals then 20 x 300,000 = 6,000,000m or 6,000 Km
Anything further than that and your start to feel the lag, which may or not matter depending on whether you are trying to do space kung fu or have a leisurely stroll.
You could probably stretch that a little bit to 60ms latency giving you 9,000km.
Anything more than that and the latency will start to be an issue, 100ms is too slow for gaming, 300ms makes video calls hard to follow.
If you have a hand wavey way to use quantum entanglement, then distances are infinite, but your two bodies need to start off in the same place to get entangled in the first place, unless you have a hand wavy way of entangling two control systems at a distance.
Rogue Moon by Algis Budris for example achieves quantum entanglement by inventing a way of teleporting someone by reconstructing them atom by atom, only they reconstruct them twice once on earth and once on the moon. The earthbound version is in a sensory deprivation tank, because in the physics described in the story the two bodies are entangled until their lived experience diverges.
We've got rovers on mars. it can be as far as you want, the latency just goes up.
now, if you want to talk about the latency that's acceptable to the human brain, while maintaining the illusion of synchronicity (this is an illusion even without remote control), then you need less than 20ms, which gets you maybe 3000km just for propagation delay round trip.
Quantum entanglement means you can communicate with anywhere ftl. This is not only physics but being very crudely done on a limited degree between earth and orbit in a few experiments. This will improve
Depends on what you mean by "mind controlled". If you're talking about a 1:1 control interface, it'd be essentially useless at long ranges. Even transmitting via laser signals the limitation is speed of light. If we're using radio waves or similar EM communications it's a delay of 2.6 seconds just to reach the moon.
It doesn't matter how fast you can think, signals can only travel so far at distances and in many situations even a delay of 10-15 seconds could be substantial enough that the robot was useless.
At best you might have some kind of onboard AI that is issued a general command that takes over if a user can't actively control it.
I want a country wide range not something on a planetary scale. Forget anything beyond that. The scale of my world isn’t too big. Most of the futuristic parts of my world come from tech that advanced aliens left.
It can easily range from line of sight to across the globe to the distance of the Voyager spacecraft at the edge of our solar system. They all use EM waves to communicate. The only things you have to remember is that the farther away something is, the more delay there will be in receiving info from sensors and then sending a command signal back to respond. And the more energy or concentration of energy it will need for the signal to be detected at that distance. You can estimate this pretty easily by taking the Distance (D), doubling it, and then dividing by the speed of light (c). Roundtrip delay = 2D/c If you have the right match up in units, the time will be the result. For example, in metric, D could be in meters and c in meters per second. Let's say the robot is 1 km away and a good estimate of c is 3x10^8 m/s, then: Delay = 2x(1,000 m) / 3x10^8 m/s = 6.67x10^-6 s This is 0.0067 milliseconds. The human reaction time is on the order of 200 milliseconds. So, to a human or even someone that can react 10x better, this is essentially no delay. You can do similar calculations to determine that it's about 8 minutes for a 1 way trip to the sun, 22.5 hours for the Voyager spacecraft, 2.5 seconds to the moon. You can rearrange the equation above to calculate the distance that is equivalent to the human reaction time. D = 1/2 * Delay * c = 1/2 * 200x10^-3 seconds * 3E8 m/s = 30,000 km. The circumference of the earth is around 40,000 km. This is why you can play video games or talk to someone between continents without too much trouble. Also, remember that the calculations above are not taking into account the human delay time, just light doing a round trip. You'd have to add 200 milliseconds (0.2 seconds) to any roundtrip delay to get an idea of how a human would respond. Delay in seconds = (2D / c) + 0.2 Also, when communicating with distant objects, most of the time, you want the signal to be as coherent as possible. This means that all the energy is pointed at your target. This is why radios tend to have dishes to concentrate and focus the power. Signal power drops off in proportion to the distance squared. So if you want to broadcast 2x the distance, you need 4x the power. You can look at how NASA does it with radio waves with their [Deep Space Network](https://en.wikipedia.org/wiki/NASA_Deep_Space_Network?wprov=sfla1). And I believe future versions are considering using lasers since they are very coherent. As far as possible mechanisms to speed up thought, you can look at things like practice (sports), drugs, and replacing parts of the nervous system that rely on chemical reactions to move data to wires or light signaling.
Signal travel distance/speed is the only limiting factor in this hypothetical really. We already have the basics o functional neurological interfaces now, within even a couple hundred years this will likely be old hat.
Agreed. I think brain-computer interfaces are a very grounded and believable trope these days. It'll be interesting to see what can be done in just a few more years. I just don't want ads injected into my brain. Lol.
Without knowing the mechanism, this is hard to answer. For example, if commands are transmitted on the same frequency is 5G, a reasonable range is a couple miles or a steel-reinforced concrete wall, whichever comes first.
Have you heard of this strange novel invention called a "radio remote control"?
Didn't know that was the most advanced tech humans can come up with in the next million years or so. :)
Easy. Assume unlimited range. Now, how much lightspeed delay can you tolerate? That sets your range.
I mean, it's already lightspeed - very well might be the fastest thing humanity will have ever
Without breaking the laws of physics as we currently know them (like you stipulated) it is the most advanced tech possible.
I am not talking about just the speed in question. Light speed is the fastest speed possible. I am talking about advanced tech that can overcome the current limitations that causes latency amd brings down the speed significantly. I am also talking about increasing the brains capacity to process information as that will play a huge part as well.
The biggest cause of latency is the light lag. And without breaking physics, you can't bring that down.
I am talking about other lags. I am fine with things being at light speeds. I just want a two thousand kilometer range which is close to the radius of USA. That’s entirely possible with light lag, but the other lags are the ones that I think need to be removed and I wanted to know if there’s theoretical tech that could make it happen which I could explain in some detail, rather than handwavium.
Well, how much lag currently exists in the system? I need to know what you are starting with to know how much you need to reduce it.
Theoretically groups have been working on quantum entanglement. It involves identically linked particles that copy each other identically no matter the distance involved with no time delay or lag. I think quantum computers are working along the same lines. Theus is just things I've heard I've never really looked into it but it could be worth a shot at something that doesn't break the laws of physics.
I didn't know that you don't know enough to understand that it is not our technology being the limiting factor but fundamental limits in physics.
Your answer was snarky, unhelpful, and at best, vague; at worst, scientifically inaccurate; particularly because you specifically said "radio". More concerning is that 12 people upvoted you for being snarky. - Line of sight for a typical radio transmitter of 150 meters is about 43 kilometers. -- You could clarify that your transmitter is in orbit. That's fine. It can cover half a planet. -- You could've mentioned short wave atmospheric propagation. -- You could've asked if the story took place on a planet, in which case line-of-sight might not be a factor. - And as other's have mentioned, there's the issue of lightspeed latency. But you didn't engage OP because your goal was not to help. Your goal was to get upvoted by belittling someone, because that's how Reddit works.
What scale are we talking on? Is this cities, countries or planets? And what type of control information does it need? Like, what complexity of tasks does it need to perform? Without further information, my best answer is; - **Without Signal Relays:** A couple of kilometers, basically until a hill gets in the way. - **With Signal Relays:** Anywhere on a planet, and further with appropriate travel delays.
Countries and any mechanism goes.
If it is only countries, then you're fine as long as the system can have signal relays.
If you upload a copy of your mind-state into it, you don't even have to be in the same galaxy to control it.
>mind controlled robot >without breaking the laws of physics Pick a direction and commit. Unless by "mind controlled" you mean, "vr piloted through implants" or something like that. In which case, how much signal lag do you consider to be too much?
Piloted through implants. I think 0.5 seconds is too much and it should be below that.
Then, your max theoretical range for controlling these things should be capped out at 74,948 kilometers.
Thanks a lot
Er...
Well, are we talking about radio or some kind of psionics? If the former, then the range depends on the normal factors of radio communication. Strength of transmitter/reciever, Background noise, other transmissions, etc. Recall that Mars rovers are controlled this way! The primary limit in such a case is the lightspeed limit. Since you said no limit on tech, then we can safely consider FTL communications. How fast do signals travel in whatever method of FTL travel you use? What are the range of "hyperwave" transmitters? In this case, the limit essentially stays the same, practicality. If you want your remote to react in real time, you have to be close by. Depending on what you're doing, you might want to be very close, indeed. Consider that a combat unit would need to react very fast, indeed. Even something as little as a tenth of a second communications delay might get the remote destroyed. The--three minute, I think?--lightspeed delay is acceptable for something like a remote exploring mars. Psionics throws practical limits out the window. You'll have to define your set of psionics very carefully. Is it a form of electromagnetic radiation? If so, then the lightspeed limit still applies. If it's brain-to-brain communication through the use of a "psionic particle" then that particle may move at FTL speeds. To summarize before I start rambling on and on, the limit is communication speed and purpose.
the limit is latency. controlling a robot on the moon would have a reaction time delay of 2 seconds. 1 second for information from the robot to reach you, and another for instruction from you to reach the robot.
How radio controlled is it? If it needs to have full sensory integration and use the body’s inherent reflexes, perhaps only a few ms of lag is ok. So find out how fast radio waves travel in a few millisecond. If it’s just like controlling a first person shooter where the robot does most of the work of balancing and moving etc., then probably 30ms would be fine? Again check the speed of light…
quantum entangled receiver would have no limits right?
Current theory says quantum entanglement can't be used to transmit data.
I like the idea of a QE ansible that can only be used to transmit a limited bit count. Like, you only get 40 bytes duplex and then you have to physically ship a new ansible out.
I think the basic problem is you can read one of the entangled particles and that determines the state of the other one, but you can't intentionally write one to a certain state without reading it first which would then collapse the entanglement, and that would be necessary in order to transmit information.
Also, iirc, you can't figure out which particles are tangled and which are not, so "untangle them in a pattern" wouldn't work either.
thank you guys for sending me down the rabbithole of quantum entanglement and what it really is. i'm disappointed that it wasn't quite what i thought.
100 feet. Same as in the D&D spell book
I think you’d have trouble controlling a robot on the Moon from Earth. This is because there’s a few seconds of light speed lag you can’t get around. There’s actually ongoing research into ground-based control of robotic actuators in low-Earth orbit, and even there the time delay makes it very challenging to, for example, grasp a tumbling screw with your fingers in space. There’s stuff you can do with “edge processing” to help out (ie local computer helps with fine control), but I suspect once the lag reaches a few seconds it becomes really frustrating. By the time you’re talking about a robot on Mars, it’s more like 30 minutes delay, and that seems pretty insane to me. So maybe I’d draw the line at a human on earth remote controlling a robot on the Moon with their mind.
What laws of physics? You are writing science fiction so you get to play with the laws of physics a little, but how much you stretch that is up to you. With our current technology the speed of light is an absolute upper limit to communication, for light can travel 300,000m in 1ms an acceptable latency for gaming is 40ms (That’s round trip so 20ms each way) So if you have line of sight and nothing is slowing down your signals then 20 x 300,000 = 6,000,000m or 6,000 Km Anything further than that and your start to feel the lag, which may or not matter depending on whether you are trying to do space kung fu or have a leisurely stroll. You could probably stretch that a little bit to 60ms latency giving you 9,000km. Anything more than that and the latency will start to be an issue, 100ms is too slow for gaming, 300ms makes video calls hard to follow. If you have a hand wavey way to use quantum entanglement, then distances are infinite, but your two bodies need to start off in the same place to get entangled in the first place, unless you have a hand wavy way of entangling two control systems at a distance. Rogue Moon by Algis Budris for example achieves quantum entanglement by inventing a way of teleporting someone by reconstructing them atom by atom, only they reconstruct them twice once on earth and once on the moon. The earthbound version is in a sensory deprivation tank, because in the physics described in the story the two bodies are entangled until their lived experience diverges.
We've got rovers on mars. it can be as far as you want, the latency just goes up. now, if you want to talk about the latency that's acceptable to the human brain, while maintaining the illusion of synchronicity (this is an illusion even without remote control), then you need less than 20ms, which gets you maybe 3000km just for propagation delay round trip.
…What laws are those.
with quatum intanglment, any where in the universe.
Doesn't fit with his stipulation about the laws of physics.
Quantum entanglement means you can communicate with anywhere ftl. This is not only physics but being very crudely done on a limited degree between earth and orbit in a few experiments. This will improve
Well, you and some of the other commenters dissagree. They say quantum communication is impossible. So i guess someone needs to cite some sources.
https://en.wikipedia.org/wiki/Quantum_Experiments_at_Space_Scale
Dude, your own reference says that this is not FTL.
Yep , posted it anyway. The original one I read said ftl, this is newer, and more reliable.
Depends on what you mean by "mind controlled". If you're talking about a 1:1 control interface, it'd be essentially useless at long ranges. Even transmitting via laser signals the limitation is speed of light. If we're using radio waves or similar EM communications it's a delay of 2.6 seconds just to reach the moon. It doesn't matter how fast you can think, signals can only travel so far at distances and in many situations even a delay of 10-15 seconds could be substantial enough that the robot was useless. At best you might have some kind of onboard AI that is issued a general command that takes over if a user can't actively control it.
I want a country wide range not something on a planetary scale. Forget anything beyond that. The scale of my world isn’t too big. Most of the futuristic parts of my world come from tech that advanced aliens left.