Theoretically, if you engage in a so called Full Dive VR, you can — inside the simulation — experience things at an accelerated rate, meaning your subjective experience is many hours, while mere seconds have passed in real life.

I want this for my world, but I want to place a limit on it.

I have tried to look for this concept in other fiction, to see how they deal with it. The only instances I could find of this in are in Altered Carbon where it is used as a form of torture/learning, and in 2 episodes of Rick and Morty where both of them live "full lives" in minutes. Especially in the case of Rick and Morty, both of them still have their base memories, but have the knowledge of their VR lives, as well.

I've tried using Copilot, but obviously without doing more research myself in an attempt to understand this already limited topic, Copilot and I are left guessing.

My process is similar to Cyberpunk 2048's Braindance, but there can be time acceleration. I want the time acceleration to be a fixed amount due to biological restrictions. For example, the max is 100 years for every hour that passes in the real world before running into side effects. I want to change the max amount based on the species making use of the technology, but I need to first see if I can have a max at all.

Why would there be a cap to the time limit?
What would be the consequences of staying inside a FDVR, outside of physical changes?

The reason I want a limit is because without one, the question "If people can learn 100 years worth of information in an hour, wouldn't everyone be a pro?" comes to mind. Yes, I understand that just because there are ways to get better at something doesn't mean people will do it, but when all you have to do is put on a headset and sit for an hour to become amazing at something, it makes little sense not to do it.

The only thing that comes to mind is that the person experiences the learning of information in what feels like real time. This could make learning exhausting because you're experiencing years of non-stop information gathering in what feels like real time. This can also lead down the "your real life is in VR and you forget your old life over time."

Wouldn't it make more sense to have your memories overwritten by the simulated 100 years?

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    $\begingroup$ Comments have been moved to chat; please do not continue the discussion here. Before posting a comment below this one, please review the purposes of comments. Comments that do not request clarification or suggest improvements usually belong as an answer, on Worldbuilding Meta, or in Worldbuilding Chat. Comments continuing discussion may be removed. $\endgroup$
    – L.Dutch
    Mar 7 at 18:06

14 Answers 14


Brains can simply not function that fast.

To process that much information your brain requires rest (AlexP elaborates on this in their comment: to retain information, the short-term memory needs to be converted into long-term memory, which requires (down)time). So if you were to simulate 100 years of information in an hour real time (that's more than 10 days per second), you'd have to do it in steps of a few milliseconds (and you can't simulate the brain resting).

So requiring breaks would be a logical, natural way to introduce a cap.

Then there is the matter of capacity: the capacity of human brains to store information is not infinite. How would you control what knowledge (= memory) can be disposed of? After 100 years, even knowledge of the program itself would have to be overwritten, making such a long program redundant.

For other species, both of these biological limitations could of course be different.

Ignoring those obstacles, there is still the matter of preference: not everyone will want to become highly well-educated in the fields of economics or statistics. So even if everyone is a pro in something, no one would be a pro in everything.

What would be the consequences of staying inside a FDVR, outside of physical changes?

Apart from a fried brain (:))—lost random memories, probably even alterations in personality, depending on the information and the user's ability to process it and their background: all the information will have to be meshed with the existing data, which will require making connections, relating it to former experiences, &c. This will inevitably lead to different conclusions and altered frames of reference.

Another possible consequence is body disassociation: according to a user's experience, they have spent years controlling and manipulating a body that is not their physical one. Even though it could be a representation of it, the connection between mind and body differs on such a level that they have to grow accustomed to their own physicality again, which is awkward and unsettling.
(I'm not certain if a perfect simulation would cause such a psychological disorder, but perfection is unlikely, and this seems a very realistic possibility.)

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    $\begingroup$ You may want to add that human brains make a clear distinction between short-term and long-term memory, and that they need a significant amount of down-time to make long-term memories. Maybe a human could cram ten hours of reading into one our of wall-clock time, but they won't learn anything; to learn stuff they need to convert their short-term memories of what they have read into long-term memories, and that's not going to happen in such a short time. $\endgroup$
    – AlexP
    Mar 6 at 14:58
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    $\begingroup$ Another point you could add (I don't have the rep to create an answer): The person coming out would not be the same as the person coming in. You found the woman of your dreams and want to learn to dance for the wedding. You spend 10 years perfecting it. Do you even still love her? Imagine coming back after 4 years of college and nothing has changed. Your best friend is still playing the same game. Your dad is still cooking dinner. Mom's not even home from work yet. Who are these people? $\endgroup$
    – Cohnal
    Mar 7 at 8:07
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    $\begingroup$ @Cohnal "I don't have the rep to create an answer" That's strange, (creating a post - Q or A)[worldbuilding.stackexchange.com/help/privileges/create-posts] should be possible from 1 rep - and you have a lot more. $\endgroup$
    – zovits
    Mar 7 at 12:05
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    $\begingroup$ @Cohnal you do have rep to answer, everyone can if the question is not protected. So feel free to do just that. In fact, commenting does require 50 rep while answering requires zero. $\endgroup$
    – Vesper
    Mar 7 at 12:06
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    $\begingroup$ It's worth noting in the capacity paragraph that human memory isn't first in first out (FIFO). The assumption that the oldest knowledge is what gets wiped or overwritten has no real bearing on how human brains work. $\endgroup$ Mar 8 at 13:35

Brains produce degradation products while working. They use up sugar, they produce heat, they produce waste-products, that are transported away by cerebro spinal fluids at night. These byproducts are prime suspects in long-term braindamaging diseases like alzheimers etc.


If we do not sleep, or experience several days worth of mental stress in a few hours, they accumulate, creating dangerous side-effects similar to sleep deprivation. Overclocking also demands extra-oxygen and extra-glucose in the bloodstream, leading to accidification and hyper-glycemia at the start and Hypoglycemia at the end, constantly going back and forth with artifical glands to support the brain.

This damages tissue similar to tissue damage in diabetus patients. It may also lead to blackouts mid overclocking.

Sensory overload - what a constant signal barrage to our poor, old chemical machines is - has other side effects: Anxiety, restlessness, anger outburst.

Finally, there is the ultimate price for overclocking and shutdown: Migraines and Epilepsy https://www.epilepsy.com/what-is-epilepsy/seizure-triggers/photosensitivity https://www.epilepsy.com/what-is-epilepsy/seizure-triggers/sleep

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    $\begingroup$ I like the comparison with overclocking -- it's an easy analogy that any tech-inclined layman should follow. $\endgroup$ Mar 6 at 15:48
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    $\begingroup$ it amuses me that the "diabeetus" meme has influenced us to the point that we fail to spell "diabetes" correctly. I had to double-check that "diabetus" actually is incorrect spelling! $\endgroup$
    – Syndic
    Mar 7 at 7:28
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    $\begingroup$ @Syndic It lifes! Language is the ultimate morphing frankenstein thing. And then we wrap it in a binder and ask little kids quizes about it, sorting them depending on adherence to the quiz about the T1000 latest shape ;D $\endgroup$
    – Pica
    Mar 7 at 8:33
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    $\begingroup$ I have the excellent idea of running with a weighted vest so I can do more running per running. At one point I did a 1h run with 10kgs (22 lbs) extra. After that I had sore muscles for 3 days. There is always a price to pay when you take shortcuts. $\endgroup$ Mar 7 at 9:04
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    $\begingroup$ I didnt even consider byproducts. Epilepsy and Migraines are great for my symptoms. The virus I'm making basically super charges the brain but there is a questionable downside. I want to make FDVR time dilation a reality for those infected but not for humans to influence animosity between humans and the infected. $\endgroup$ Mar 9 at 22:05

You rely 100% on very fictiony Sci-Fi universes as a baseline

Why (or better how) on earth would a regular human brain be capable of handling several days worth of information in a few minutes? Especially for extended periods of time? Mentally go back to school, you couldn't remember all of just one day that you experienced over the course of one day, brains would be unable to cope with higher speeds for extended durations of time.

So any low-sounding factor is probably the most reasonable: Maybe a month in a week is the limit.

Of course you can go beyond it but the user will only pick up (mostly random!) fragments of the material, or "gut feelings" about facts with 0 ability to explain them.

In terms of downsides: With increased use the connection to reality would get more and more strenuous, cue mental issues because of derealization, maybe severely degraded memory, hallucinated flashbacks, failure to discern between real and "fake-learned" events etc.

This all sounds very negative / dismissive of the tech, what would it even be good for? IMHO it wouldn't really work for "learning a year in a week" kind of stuff. But instead MAYBE at 2x speed people could learn and try out stuff with 0 cost-of-failure. No expensive equipment getting broken, no (or adjusteable) pain from that failed 720 corkscrew-backflip while downhill biking, no logistics of getting back up on the hill to try again. Instant-redos of specific moments in time where you made a mistake (aka you could finally practice just that final critical moment of a half hour buildup routine.

So you could totally learn what usually takes years in a few months. But not (primarily) due to actual time dilation, but because you could skip so many unnecessary extra steps and bits (including anything you've already learnt), be more efficient with immediate full analysis & feedback etc.

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    $\begingroup$ A gut feeling could be an interesting turn. A gut feeling is still knowing something. There are cases of people who know how to do something but cant explain how to do it granted that is more of a verbal-structure thing than a mental thing based on what limited info I saw. I was for sure gonna include instances in FDVR segments of regarding a lot of what you said. Sadly uninfected humans wont get to partake. $\endgroup$ Mar 9 at 22:12

Super Speed does not mean you do things faster

... at least not from your own perspective.

Hand waving away the obvious problem that such a simulator would probably fry your brain, the only way one could function at accelerated speed is if your perception of time slows down in proportion to the acceleration in the real world. Want to read the LotR trilogy in a fraction of a second? Sure, you can do that, but from your own perspective, you're just sitting there reading books for hours and hours on end. Want to learn the entire street layout of New York City? Sure, that will just take a few moments... except from your perspective it means spending the next 2 years of your life just walk around. Want to become a master of mixed martial arts? Sure, but you still have to put in your 10 years of training like everyone else, you just don't need to put your real life on hold to do it.

See: Super Speed is the WORST Super Power

People also need to make the VR simulations

Also, you have to keep in mind that these VR simulations have to be built by someone. Even with AI assisted content creation, it all still has to be curated, prompted, and edited by actual human (or alien) experts. So, making a simulation with 100 years worth of learnable content is a LOT of work. Instead most VR learning programs will be much shorter, like 1-40 hours of content. So, even if you want to grind out learning as fast as possible, there is still downtime in purchasing and switching out simulation programs IRL.

Also, keep in mind that the cost of making a long simulation means that unnecessary features will not be common. That 1000 hour master training simulator is not a whole city full of interesting people you can retreat to for a year of consecutive learning. It's just a classroom with a lector that only knows how to tell you the lessons, and answer basic questions about the subject. After the first few hours of class, you'll get bored and WANT to go back to the real world to rest, have human interactions, etc.

Why dedicated individuals still don't know everything

Simulated Time comes with the same major drawback as real time... eventually, you forget things. A 12 year old kids might have a 100 years of living under his belt from all that time he spends in VR, but like a natural 100 year old, it's really hard to remember stuff you've learned and not practiced in the past 99 years; so, your 12 year old won't remember being 11 or most of the cool stuff he learned in the first 90 years of simulated training except for what skills he keeps coming back to. In short, you can learn a lot in VR, but no one is a master at anything they don't maintain.

Why some aliens can learn faster than others

It all comes down to attention spans. Some aliens have no problem sitting through a 30 simulated hour lecture while others may get bored and lose focus after 30 simulated minutes and need a break to reality.

  • $\begingroup$ Ye, I didnt really think there was a way to go about allowing a non-enhanced human brain to have increased perception. I figured these were gonna be the answers. I just needed confirmation to force myself off of the idea and pivot to using it to influence animosity between humans and non-infected. $\endgroup$ Mar 9 at 22:16

People won't want to

The question is, why don't people spend years on end studying without pause as is? Because they don't want to. Sure, "in real life" the time might not pass, but your VR pupils still need to actually go and spend the time to study. For them, that is real time spent.

I think that a lot of schooling would happen with time-dilation VR in those circumstances, but most people simply wouldn't want to sit down and study for 100 years with full discipline.

  • $\begingroup$ I addressed this point in my post. I understand that it can be as easy as people being lazy. I want to know if there are any additional consequences that straight up prevent or discourage using it VR for learning. I want to know if he virtual "real time" can be a sufficient consequence. I cant justify making it a consequence unless memories are overwritten in virtual "real time" or actual real time. $\endgroup$ Mar 6 at 8:15
  • $\begingroup$ That being said, you could always use those 5 minutes before dinner is ready for a full on 3 hour study session, so no more time pressure $\endgroup$
    – Hobbamok
    Mar 11 at 8:27
  • $\begingroup$ @Hobbamok yes, but from personal experience, more time doesn't necessarily solve problems with studying. If you still procrastinate 75% of your compressed time, it doesn't matter. $\endgroup$
    – MarsMagnus
    Mar 12 at 7:25
  • $\begingroup$ @MarsMagnus oh yeah, procrastination will get massively worse. But those who don't struggle with it will be able to achieve even more than already. So you could construct a very interestng divide between people in this world in this regard. Insane overachievers vs absolute chronic procrastinators $\endgroup$
    – Hobbamok
    Mar 12 at 9:10

VR is dependent on the mechanisms for dreams and is prone to Dream Logic

Simulating every aspect of reality is technically prohibitive, and not needed 99% of the time, as there are many scenarios that very few people will choose to experience in any sort of depth (although I suppose there has to be a community that is obsessed with simulating the life of a lefthanded Algerian shepherd dealing with dyscalculia), so the VR system uses the human brain itself for sourcing facts and determining how things work, with additional details looked up on the fly for technical things that a person might not experience. Unfortunately, that means that the experience can be heavily influenced by the user and what they believe. For shorter simulations, the effects of this are negligible, particularly since most people use VR for the same sort of escapist fantasy that one often encounters in dreams, but when used for longer periods of time, it diverges further and further from reality, and lessons learned become actively false as the "one little trick" that works in the dream that the learner comes to recognize as a basic principle in the skill doesn't actually work in reality.

And that's not even getting into the human brain having a tendency to skip the details of repetitive tasks by essentially montaging it, meaning that attempts to practice blacksmithing tasks for a period of several years often results in people exiting the VR scenario with a vivid memory of having spent years in the smithy... which are just memories of having done so with the details being vague, or obviously being filled in on the spot as the person tries to remember and the brain helpfully tries to fill in the placeholder.


Let's consider a few cases where frame jacking might actually be possible. Each of them has significant implications on how they might be limited.


When compressing video as an MP4, you get a key frame, then changes that have happened since that key frame. For the human experience, this becomes a lot like dreaming, where if you don't specifically ask about the color of something, then the color information isn't passed to you.

The downside of this technique is that you don't get all of the information, leaving you with a possibly corrupt version of reality. If those corruptions build up, you could suffer from insanity or severe cognitive dissonance.


For this version, your consciousness is transferred to a machine substrate that lives things for you. Your brain is already going about as fast as it can, so it isn't going to actually learn things faster. What this will do is reference your brain for important decisions and feed back the important results.

For you, the actual human brain, this would be extremely disorienting. It would take a lot of training to relax into the disorientation and accept the response back from the coprocessor. It would result in a dream-like state, where you would think an action, and the co-processor would immediately let you know the results of that action without having to go through your body or senses.

Another possibility is that you could suffer overload of the sensory cortexes that receive the information faster than you can process it. Fever conditions could produce swelling that result in brain damage.

Check out/check in

This is like the co-processor option, but it makes a copy of your mind that wanders around while your body is in an induced coma. Eventually it returns to your body by writing its memories directly to whatever stores memories in our brains.

The disadvantage to this is that you won't get actual experience, so your brain won't re-wire itself with skills. You just remember having done something, get the results from it, without actually having done it.

If you can do this, then you can also do direct memory insertion of languages and schematics, so this version is probably OP for all purposes.


Frame challenge: assuming these people are still thinking with a squishy blob of neurons, then it's quite impossible for them to actually experience a century of time within an hour. The brain is only capable of perceiving events at approximately real-time. And while our time sense is very inaccurate and can be distorted and fooled, it's not to such a degree that we can be made to confuse a century with an hour.

So, what the system actually does is give the impression of having experienced that time, rather than the actual experience. This essentially involves inserting false memories with projections of what the user might do, and relying on the user's own mind to fill in the gaps, as happens anyway with real memories. Rather than attempting to actually simulate the user and a fully interactive world, a series of plausible scenarios is generated and the user's brain is probed to determine how acceptable they find the proposed events, before one is selected and becomes the user's new experience.

This takes repeated cycles of modifying memory structures and probing the user's brain to determine their reactions to major events and whether there's any basic conflicts with the overall "storyline" being composed. This takes time, but far less than having them actually experience the full stream of events, and it uses vastly less processing power than actually simulating a hundred years of experiences. However, it's necessary to take the time to perform these checks, as taking shortcuts to speed things along can lead to trauma and other cognitive and psychological issues as the user remembers doing things they wouldn't have done.

  • $\begingroup$ Human brain perceiving events at real-time is a bit fuzzy actually. Like you can perceive stuff sped up. Visually impaired people use screen reading software to read out websites, but they can actually get through stuff quite quick, being able to understand speech being spoken out like 4x faster than normal. And also in VR you could for example play a game that is sped up, the brain can still process it. So nothing at the levels op is suggesting, but can still be faster than "real-time" $\endgroup$
    – HSharp
    Mar 7 at 10:54
  • $\begingroup$ @HSharp experiencing a century in an hour isn't "a bit fuzzy", it's nearly a million times faster than real time. And being able to understand speech at 4x speed is rather irrelevant to perception of time, it's obvious that it's sped up. $\endgroup$ Mar 7 at 13:21

I'd say that there are a few ways to tackle this. Aside from all of the already noted drawbacks and potential problems, there's also the matter of comprehension.

For instance, I love listening to audiobooks, and tend to listen to them at 1.3x speed. For some, this would be problematic. For others, 1.5x or even faster speeds might be a preference without a loss of comprehension. 1.3x just happens to be my sweet spot for listening to and retaining an audiobook. Consider it a bit like speed reading. For some, they can read at astounding speeds, but only have something like 60-80% comprehension/retention. For others, they can read at those same astounding speeds and have closer to the same retention that a "normal" person might have at "normal" reading speeds.

Plus, everyone is different. Some folk have eidetic memory while others can't retain new information virtually at all.

Ultimately, you need to determine some cap to the acceleration at which the average user can actually retain anything. A century per hour is... not plausible. Sure, you can handwave it away, but without some external biological changes or external technology, it's just not feasible.

So, you could either:

  • Handwave in some new biotech where brains can be exposed to manufactured biochemicals or something along those lines that allows the capture of memories to be incredibly more efficient in both speed and retention, or
  • Use something like NeuroLink or some other brain interface device that stores memories off to an implanted tech device - though if this were the case, it could almost make more sense for the experiences to be something just written directly to the device

The bill

VR experience has a cost per frame. If you use up more frames per second, you pay more per second.

This ensures that such accelerated time is only available to the rich and powerful individuals, and governments.

By the way this is just like in real life. Companies like Amazon and Microsoft will bill you by how much computing you use in their respective clouds.

  • $\begingroup$ Interesting. Right now it's Human v Infected Humans. Humans cant use the FDVR but infected ones can. I needed more reasons to stir up hate and this is a great suggestion. $\endgroup$ Mar 12 at 3:28

I did some searching and according to this article written by a professor at Northwestern University the theoretical limit to memories is 2.5 petabytes (2.5 million gigabytes) which is equivalent to downloading 300 years of television on a DVR. Since that limit is significantly longer than what you were looking for, here's another possible idea for a consequence that could work instead.

Spending too long in FDVR is dangerous

In one book I've read there was a neural interface VR headset that intercepted the signals sent from the brain to allow movement and senses to feel completely real. With the neural interface headset there was no time dilation, one minute was one minute, but it did still have a consequence. The headset used microwaves to interact with the brain which is harmless in small amounts but if it was used for more than 12 hours at a time it can begin to damage the brain, and if used for more 24 hours it can even lead to a sudden death (it would have to be a much swifter death for yours though). I'm not sure if microwaves being used is realistic at all but the idea behind it can still work so your headsets don't have to use that specific cause for why they can damage the brain from overuse; you can just handwave the exact reason why those headsets are dangerous if it would be hard to justify for however they work.

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    $\begingroup$ I can't speak on the plausibility of using microwaves to stimulate neural activity, but I am relatively certain that the only harm microwaves could present to the brain would be in the form of heat. So if the OP does go that route, it's likely an early-warning sign of overuse would be symptoms of heat stroke $\endgroup$
    – M S
    Mar 6 at 14:30

Apart from the other excellent answers that went on to explain the biological limits I would like to remark two more, one sociological, one referring to the brain:

Emotional distance

While you may only be away from your partner for an hour you experience a hundred years of virtual reality relations. As a comparison when I was doing an exchange program many of the fellow exchange students put a hold on their relationships (most of which ended with breakups). Imagine all of your human relationships going through that at once. Hobbamok IMO correctly says that this leads to derealization, where you will feel that the VR relations are more real than the real world.


Three weeks ago I made a dumb mistake about my own major that I finished 10 years ago. Imagine what would happen if I spent an hour in the machine that teaches me a new trade, I would have completely forgotten everything I professionally use and my knowledge would be - while expanded - considerably more academic.


A: Brains can't work that fast. mentioned elsewhere.

E.g. you cannot really learn to be a page at a glance reader with reasonable retention.

So generally accelerated time would be limited to a factor of 3-5 over biologic time.

But see Niven's description of different kinds of time in Dream Park. Anticipatory time, event time, reflection time. A 10 second ride on the CrackTheWhip ride turns into a major event.

From experience on canoe trips, I remember the rapids, the storms. I "compress" the hours of mindless paddling. this sort of thing could be encoded as a "this loop repeats enough time to use 6 days". But you remember it from Deep Dive the way you remember real events -- markers for the time passing, but not many bits of info.

B: Sleep seems to be a time where you process events of the day to make permanent memories. Men in WWII on convoy duty were on long stretches where they were only getting 2-4 hours of sleep a night. Even when writing logs at the time, they are very disjointed. Fortunately the navy trained as many jobs as possible to be rote. This limits the amount of bio time you can be under.

C: The VR human interface has a limted bandwidth. The faster you go, the less detail you get. The human has to interpolate the details of events. A good VR experience has pre-loads where backgrounds can be experienced at various times so that the participant can fill use these to fill in the details later.

This happens in real life. You can take a family on a trip to Disneyland, then later talk about how much fun the kids had meeting Bugs Bunny. The kids will fill in details around Bugs.

This brings up another possibility: Advertising/Propaganda/Brainwashing within a VR.

Example: Imagine the grim possibilities of a VR version of Conversion Therapy. You could create environments where you could give someone a years with of childhood trauma in a day, if you could operate at high speed.

D: Perhaps you have drugs that can enhance it by another factor of 2-3. Or perhaps by running the person at a higher temp (Overclocking the cpu) you can increase the rate (doubtful. Brain chemistry isn't temperature adaptable. Look at the effects of only a few degrees of hypo or hyper thermia.)

E: The client's brain is scanned, and the entire simlation is calcuated in a computer, reasonable memories encoded, and then embossed back into the brain. Neat trick. Furious handwaving. Ths could allow massive speedups.

F: The entire culture is online. Most of the world lives at 100 to 1 speedup. But the physical world still needs fixing. So people have to be downloaded into 'wetware'. 3 days in the real world,and a year has passed in The Good Place.

Other mentions in literature: See Heinlein's The Number of the Beast. Three time axes. T is our time, Tau is at right angles to T. Time spent on the Tau axis doesn't take any time on T axis.

This compounds your problem, as there is no limit to the ratio, other than the problme of logistics moving people from axis to axis.


Accelerated VR is low-quality

It's not a capacity limit, but accelerating the perception of time while feeding in sensation over the same wetware probably results in a noticeable degradation of quality. Think magnetic tape for audio and video. At high rates of travel the quality is fine, but if you slow it down to fit more onto the same tape, then the noise levels go up and eventually it's unusable.

The differences in sensation would probably manifest in ways that would hinder useful skill formation. They might even cause maladaptive skill formation, resulting in say bad motor skills outside of VR.


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