My story is sci fi and how can characters who can move their consciousness into another body and use that body to fight with work? The character may have years of fitness training, but what if the body is not strong enough to wield heavy weapons at ease or are exhausted easily, or how about the simple fact of it’s a different body that doesn’t feel the same way.
This is an open question. There’s no solid answers. We can’t, currently, transplant your psyche to a new body, and as a result there’s no, “real world,” answers.
The closest similarity is a poor comparison. Limb transplants have a lot of considerations that simply wouldn’t be a factor here. For example, they have difficulty with fine motor control, but that has more to do with their own nerves growing into the transplant, rather than a consideration that would apply with swapping bodies.
In spite of the name, muscle memory is (probably) stored as chemical chains in the brain. This gets into an awkward problem with this entire idea. A significant chunk of who you are is stored as complex chemical data in your brain. This isn’t an insurmountable problem, with unlimited technology you could probably move these between subjects. So, if you’re able to move memories between bodies, you can probably also move muscle memory. However, the transferred muscle memory might not match the recipient body, meaning it could be useless or even actively harmful.
There’s also a difficult topic mixed in. If you’re moving memories around, even replicating “the consciousness,” you’re still not moving between bodies. There’s no continuity of self. You’re moving the data, and then (maybe) deleting the original source, but that doesn’t mean you’re actually in a new body, it just means a copy of you has been created. This is a very specific variant of the Ship of Theseus paradox.
Ship of Theseus is a fairly simple thought experiment, if you replace every single part on an object over time is it still the same object? The titular ship was put on display, but as components aged and decayed they were replaced with fresh ones. After a century of this there were no original parts left. At that point the question became, “was it still the original ship, or had the complete replacement over time transformed it into a replica?”
When you’re talking about someone’s identity, the stakes get a lot higher. It’s an abstract question about an inanimate object with some sentimental or historical value, it’s a very pertinent, and immediate question for someone who’s living in a world where they might not be the person they think they are.
When you start digging into what makes an individual who they are, things get really messy. A lot who you are chemical data stored in roughly 3 lbs of tissue with a consistency similar to butter. Some of it is volatile electrical data, though that may be directly tied to the structure of the brain. The idea that there is a concrete, “self,” is very comforting, but as we dig into this, the reality seems to be more of a gestalt.
So, on the topic of the Ship of Theseus, are you the same person after switching bodies?
I don’t have a definitive answer. No one does. We have speculation, but even if you were presented with the actual phenomena, it would still be a challenging question.
As for heavy weapons, that’s not going to be a problem. As we’ve pointed out many times, heavy weapons aren’t that heavy. Greatswords weighed less than a house cat. This isn’t as true with heavy firearms. Anti-material rifles or automatic support weapons can be difficult to haul around, but you’re not going to be running around with them, you’ll set them up and operate from a stationary position. It doesn’t matter if your 12.7mm rifle weighs 30lbs, you’re going to be laying down, with it partially concealed before you start firing. Also remember that heavier machine guns will operate from vehicles or stationary mounts.
For hand to hand, body hopping is probably a serious issue. If you’re overwriting the muscle memory, then all of your reflexive reactions and your conditioned responses will be, “miscalibrated.” If you’re not overwriting the muscle memory, that suggests the technology allows for significant editing of what does, and does not, get transferred over. We’re back to the Ship of Theseus problem, but things got even more complex, because now we’re only copying, “parts” of the subject. Also leads to a weird question of: What’s left in the new host brain from before the jump? How is that going to affect who they are?
Since I got distracted a moment ago, if the muscle memory is being retained from the original host, then the transferred user will be limited by what the previous owner(s) conditioned into their body.
This raises fundamental questions about how much we adapt to our bodies. The human brain is a very adaptable organ, but this is a scenario where there really isn’t any good comparisons.
If you want some other thoughts on this, Richard K. Morgan’s Altered Carbon is an obvious choice. In his case, the characters store their consciousness digitally on a implanted data storage device. He also posits the use of “hard wired reflex packages,” which allow users to have functional muscle memory and combat capacity after swapping bodies.
On the other end of the spectrum we have SOMA from Frictional Games. This one is interested in persistence of self, and if someone is the same person after being moved between bodies. The specific questions you’re asking don’t apply with this one, but the game may be useful for feeling out larger philosophical themes.