I suspect that we probably agree on most things, so let’s try to find something we disagree about!
I think we probably agree about the following (let me know if I’m wrong about any of these):
Damage that seems like it should destroy information often doesn’t. Our intuitions are often wrong on what can be inferred, and the bias is normally in the direction of more information being lost than is actually lost. We tend to think something’s “a mess” when it can actually be fully reconstructed.
Even with a frozen brain, you can’t prove that any information relevant to restoring a person is truly lost. Straight freezing crushes and disrupts brain tissue, but maybe there’s enough biomolecular information to reconstruct everything. I personally wouldn’t be that surprised if this was the case.
There’s some physical change in the vasculature of brains that happens post-mortem and causes difficulty in re-perfusion, and that change happens at approximately the 7-15 minute mark depending on how you measure it. Brains that sit with blood inside them, but no blood flow, for longer than this window, will not re-perfuse uniformly with blood, washout solution, or fixative, but instead there will be sections of brain that fail to perfuse.
Brains can become severely damaged and even outright necrotic in some areas pre-mortem, before the person’s heart stops and legal death could be declared. The amount of brain damage present at death depends on how the person dies, but it’s relatively common for people to experience terminal comas lasting hours to days before death.
We (humanity) know enough neuroscience today to say that some aspects of a person don’t need to be preserved. Dynamic electrical activity is one such thing that can say with confidence doesn’t need to be preserved, because otherwise it would contradict our clinical experience with DHCA.
As we learn more neuroscience, we would be able to definitively say that more things don’t need to be preserved. For example, we might be able to show that certain brain regions share so much mutual information with other regions that only one needs to be preserved, with “doesn’t need to be preserved” meaning that a person could be preserved, the thing discarded, and the person restored with no or minimal clinically relevant problems. We might learn enough neuroscience to say that inhibitory synapses don’t need to be preserved, because ultimately they are implementing non-memory-relevant network regulatory tasks. We might be able to say that the spinal cord or brainstem or hippocampus doesn’t need to be preserved, because they’re all inferable from cortex.
Now here’s where I think we differ, and it’s on what the standards for our standards should be!
What should the bar for “acceptable preservation” be today, given our current neuroscience knowledge?
I think we know enough neuroscience today to say that preservation does work as long as almost all biomolecules are preserved and the brain remains traceable after preservation, and “works according to current neuroscience” should be our minimal bar for “acceptable preservation”.
This standard demands a lot from today’s preservationists, but it’s demonstratively achievable given the work I’ve done in pigs / human cadavers over the last several years. And so we as preservationists should hold ourselves to this standard, out of humility and a desire to offer the future something they can use. If we want to lower that standard we can, but a lower standard needs to come with additional neuroscience knowledge so that we can confidently say that a lowered standard does work according to current neuroscience in spite of not preserving as much.
I think that if we always hold our “acceptable preservation standard” to be demonstrably preserving enough information that neuroscience says it works, then that both gives us the best chance to deliver to the future something they can actually use, and gives us the best shot at becoming a standard, evidence-based part of end of life care.
The “standard for our standards” should be “works according to current neuroscience knowledge.”
I want preservationists of this era to be able to be sued for malpractice because their technique was sloppy and they didn’t deliver preservative chemicals to a dime-sized brain region within 15 minutes post-mortem.
I want straight freezing, traditional cryonics, or any other method to be accepted as good techniques, if and only if they come with enough new neuroscience knowledge so that we know they’re preserving enough information that they work.
Now, I suspect you would want to argue for a different “preservation standard standard” that’s not “works according to current neuroscience”, I’d love to hear your thoughts!

So first off, I want to say that Ken Hayworth is one of the scientists I respect most in the world, and he cares a lot about precision in language and making sure that nothing gets overstated. I’ve actually asked him to be heavily involved in Nectome’s certification process, and I think his careful approach will bring a lot of rigor to that. I do think his tone with Michael was a little harsh here, and he’s erring on the side of judging a twitter one-liner like it’s a scientific paper.
I helped found Eon and am currently one of their advisors, and I think the fruit fly upload situation is one of those things that’s like this comic:
Now, I’m actually thrilled to talk about the flywire situation, because while I think there’s been some miscommunication about it due to the standard science hype cycle and the way twitter is, and I think the object-level facts are a really cool result that you guys will appreciate.
The Eon simulation is what I’d describe as a “partial upload”, using leaky integrate and fire neurons. It’s built on Philip Shiu’s work in fruit fly brain modeling (https://www.nature.com/articles/s41586-024-07763-9). Philip has been part of Eon for about a year now. The work in the tweet is showing off how Eon took Philip’s model and added a body and environment to it to make it more embodied. Check out Alex’s description here: https://x.com/alexwg/status/2030217301929132323. Is this a full fruit fly upload? No. It’s not simulating the neurons in the fruit fly’s body directly (because we don’t have them), instead it’s looking at the brain and reading out approximately which way the brain wants to move the body, then puppeteering the simulated body in the same direction. So the simulated brain is controlling the body, but in more of a “prosthetic” sense, or like how a person controls a character in a video game. The simulated brain is also getting visual information from the simulated environment, so when it turns left and there’s a thing there, that changes the pattern of information going into its simulated eyes appropriately. The brain simulation is very simple compared to how the fruit fly brain works in real life, and incomplete, but does still reproduce many interesting behaviors in spite of all the simplifications. I’ve run the simulation on my laptop in an earlier form, I can go into more details in a future post if people are interested.
I think Eon / Phil’s work is a really cool result, and the fact that it works at all is to me very impressive. It could have been the case that when we scan connectomes and simulate them with very simple mathematical models, it didn’t do anything even remotely resembling actual animal behavior. If that had been the case, I’d be slightly more inclined to say that there’s important and subtle chemical information, not reflected in the kind of information you can get with an electron microscopy that you need in addition to a connectome to get an upload working. It wouldn’t move me on brain preservation working by very much, because almost all proteins are preserved by aldehydes, but it would move me somewhat on how easy I think full uploading in Ken’s sense will be. I take the recent partial fruit fly uploading work as weak evidence that brains are going to be fairly easy to simulate, and that much of the necessary detail is inferable from the geometry of the connectome.
Over the course of the next couple of blog posts, I’d like to provide all of you with some solid resources for evaluating what we’re doing at Nectome, and let you form your own judgements from there.
Happy to answer any further questions about Flywire. I do think it’s a really awesome result, and I was pleased that the Eon team put together that video. If you guys are interested, we could even incorporate a more in-depth discussion of the project as a post in our sequence here.