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Moore's law itself may be dead but there is still additional potential to explore. Right now, CPUs are mostly two dimensional with only a few layers stacked on
by est31 7y ago
Moore's law itself may be dead but there is still additional potential to explore. Right now, CPUs are mostly two dimensional with only a few layers stacked on top compared to the extent in the other two dimensions.
Compare this to a human brain which too, has a sulcated layering system for the grey matter but the white matter connectome turns it into a fully three dimensional object. We can't produce such a thing with technological means yet.
The CPUs we produce have to be deployed in datacenters and computers within distance to each other, mostly for heat dissipation reasons. We can't just stack $N CPUs onto and next to each other until we reach an object of the size of a brain. It would not be practical to cool that thing. Compare this to human brains which require much less energy (20 Watts on average).
Moore's law is dead but it's about size of transistors. Human axons have diameters of hundreds of nanometers, even the gap of intracellular space of a synapse is approximately 20 nanometers. Compare this to the 5 nanometers we got now. We don't need size improvements to model brains, we need power consumption/heat dissipation/electric loss improvements. Also, CPUs are still very expensive. We also need improvements in manufacturing them more cheaply. Both isn't really requiring node sizes to shrink further.
Sadly, there's a different law called Dennard's Scaling which was precisely about power consumption, but it has been dead for about 13 years. https://en.wikipedia.org/wiki/Dennard_scaling https://en.wikipedia.org/wiki/Dennard_scaling
- Retric 7y agoHeat is already a limitation for going more 3D. At best you can slightly reduce latency, but with real tradeoffs.
- agumonkey 7y agomaybe in-silicon micro-vias for heat exchange ?
- 781 7y agoThe brain architecture is not the end-all of computing. For example weather prediction is just about fast math, a brain like architecture is useless here.
- est31 7y agoThe main issue is that the death of moore's law somehow implies that there won't be any progress in chip manufacturing and we'll always use the computing technology we have now because at some point you reach sizes of single atoms. But this is wrong as we don't need node shrinks, we need different improvements. And human brains are the proof that they are physically possible. Human brains, if you ignore brains of mammals larger than us, are the most complex "computers" we know of. And they are much more efficient at that and their assembly doesn't require huge buildings full of machines that cost billions of dollars. Their existence means it's possible to reach such efficiency at manufacturing and heat dissipation. It means further progress, like the one we had until now, is possible. It seems that we currently are several orders of magnitude away from what human brains achieve. Of course human flight doesn't use flapping wings nor do computers have to work 100% like brains. But they should at least be as efficient until we give up and say "no improvements are possible".
- WhompingWindows 7y agoIt's possible with organic chemistry, but what about inorganic chemistry? It's possible with carbon based chemistry, but what about silicon-based chemistry? I'm not convinced that it's impossible to build a human-mind-level consciousness in silicon, but I'm skeptical.
- est31 7y agoHuman brains actually move real stuff around for their computation [1]. Like are like abacusses or some complex clock. Silicon based computers move electrons around which are much smaller and have much less weight. However, you might be right that silicon based computers won't allow further improvements. So maybe one day we will build computers based on organic chemistry. If they are cheaper and more efficient and work as well as silicon based computers, there is certainly a case to build them. [1]: https://en.wikipedia.org/wiki/Action_potential https://en.wikipedia.org/wiki/Action_potential
- 781 7y agoHuman brains are the most efficient at some problems. This is trivial to demonstrate: try multiplying two 10 digit numbers in your head. Now pick up a calculator and do the same in a fraction of time, using a fraction of power, and with perfect accuracy.
- bognition 7y agoTo be fair growing a brain is also a VERY expensive process. To do it properly takes decades and can cost a lot of money. Luckily it looks like humanity has finally figured out how to do it at scale /sarcasm/
- imtringued 7y agoThe latest version of humanity isn't producing as many brains as it should.
- rstuart4133 7y ago> To be fair growing a brain is also a VERY expensive process. Nah, you are born with 3 times the number of synapses you will have when you are an adult. The expensive part is training that network, not growing it.
- deleted 7y ago[deleted]
- ChuckMcM 7y agoExcept heat doesn't cooperate
- hannasanarion 7y agoBrains have the benefit of an elaborate microscopic network of coolant pipes that double for power delivery
- ChuckMcM 7y agoExactly, and I've kept an eye on Nature Materials and other journals that cover advances in semiconductor cooling but so far there hasn't been anything very exciting. I was hoping the ultra thin silicon guys would use diamond as a substrate for its thermal properties (sort of like silicon on sapphire but silicon on diamond instead) but apparently not a thing yet.
- seunosewa 7y agoThe brain also runs at a much lower frequency than a CPU. A neuron can only fire about 200 times per second, or 200Hz. This is important because power consumption is directly proportional to frequency squared.
- zeusk 7y agopower and frequency are linearly related, it is the voltage that scales power in a quadratic order.
- sephamorr 7y agoThe power dissipation problem of current chips (performance is almost always power/thermal limited) is correlated with 2D structures. Communication is one giant problem: 3D structures could allow for far better colocation of connected compute elements, so we might not have to spend most of our power budget feeding data in and out of compute clusters. Scaling in 2D does make this problem easier (in some ways!), much as adding a 3rd dimension would too.
- stcredzero 7y agoThe power dissipation problem of current chips (performance is almost always power/thermal limited) is correlated with 2D structures Graphene thermal pads have really phenomenal lateral thermal conductivity. 3D computer chips could be constructed of alternating silicon and thermal graphene layers, perhaps conducting to a central core, which could be made of copper or could even contain water or a heat pipe. https://www.youtube.com/watch?v=YpphKzmDiJM https://www.youtube.com/watch?v=YpphKzmDiJM
- etaioinshrdlu 7y agoStacks of thin silicon chips of 100 layers or so with microfluidic channels between the layers, or in the layers, sounds like the way of the future to me.
- wolfi1 7y agowith the current semiconductor technology I doubt that 3D is an option for the foreseeable future. You would need a whole new implantation (or doping) technology for that
- NikkiA 7y ago> Right now, CPUs are mostly two dimensional with only a few layers stacked on top compared to the extent in the other two dimensions. Moving away from that would still be increasing transistor density and thus would not be rewriting or beating moore's law, it would still be moore's law applying.