8 ms·

Are processors pushing up against the limits of physics?

74 points by ub 12y ago

Symmetry 12y ago
Not even close, but there's good evidence they're pushing the limits of silicon transistors.
tedsanders 12y ago
Right now, the laws of economics are a bigger problem than the laws of physics. Field effect transistors have been shown to work 5nm and even 3nm. However, the new lithography technologies needed to reach those resolutions cheaply are nowhere near ready.
- idlewords 12y ago
  I heard a rule of thumb that fab costs go up about 40% with each reduction in size. Is that accurate?
  - _username_ 12y ago
    Intel paid ASML ~$4.1 billion to deliver 10nm lithography. That was ~ 1.5yrs ago (http://www.intc.com/releasedetail.cfm?ReleaseID=690165 http://www.intc.com/releasedetail.cfm?ReleaseID=690165). ASML stock is a good indicator what's happening in this business. Intel has running 14nm which is 16% better on SRAM cell than 16nm TSMC.
- runeks 12y ago
  > Right now, the laws of economics are a bigger problem than the laws of physics. The "laws of economics" and the "law of physics" are two sides of the same coin in this case. It's the laws of physics that prevents us from producing arbitrarily cheap chips, it's not two separate factors. The "laws of physics" are our hurdles, and the more we pass the cheaper the chips get.
Artemis2 12y ago
A metric that really puts things in perspective is the following: take a common consumer CPU, clocked at 3.4Ghz. That means it executes 3,400,000,000 cycles per second. Divide the speed of light by this number, and you obtain approximatively 0,088m. During the time your standard desktop CPU takes to finish a cycle, light only travels 9 centimeters.
- _username_ 12y ago
  Just a side not that light in other medium than air travels slower. It's not 300k km/h but ~200k km/h in FR4 microstrip (6"/ns where 1ns is equivalent to 1GHz clock).
  - greenmountin 12y ago
    translated: "Just an aside: note that the speed that light travels in any medium is slower than it travels in vacuum. Its speed is no longer 3e8 m/s, but a third less in, for example, FR-4 microstrip (a popular prototype board dielectric). The effective speed is about 6 inches per ns, or at least, 6 inches per cycle of a 1 GHz clock."
- bottled_poe 12y ago
  I'm not really sure how that puts things into perspective. I actually have no concept of how fast photons are whizzing around the room.
  - collyw 12y ago
    Takes light 8 minutes to get from the sun to here. (To put it in perspective.)
    - Artemis2 12y ago
      That's effectively how I see it: as a simple human, I consider light as an instantaneous phenomenon. Its speed seems to be the maximum attainable for about anything, but a man-made processor has the power to execute a simple computation in less time than what it takes for light to travel 9 centimeters. Isn't that impressive? Doesn't that cast doubt on how far we can improve our CPUs? Just remember that a thousand years ago, our beat creations were basically piles of rock.
hatethis 12y ago
No. Every single time someone supposes that any piece of technology is approaching its limits, the answer is no. Technology will continue to improve and advance as we make new discoveries. The simple fact is we do not know the future, so pretending like we know what things will be like in 20 or 50 years is just pointless. What's with this obsession of taking today's technological knowledge and assuming that things won't drastically change? Nobody should ever pretend to know what the future holds.
- comboy 12y ago
  Things will drastically change. But given piece of technology has its limits. Assuming it does not is like expecting horses to run faster than sound some time ago.
  - charlieflowers 12y ago
    "If you immediately know the candlelight is fire, then the meal was cooked long ago."
- saintgimp 12y ago
  That's a very unreasonable point of view. Sure, it's true that in the past 200 years we've had an explosion of technological progress but there's absolutely no reason to assume that it's possible to continue it for an infinite amount of time. It's rather more likely that over time we'll discover the lines that separate "hard but possible" from "theoretically impossible given the physics of this universe". The only real question is when that will happen for any given area of technology. Asserting that technology will just continue to improve and advance forever simply makes you sound like a stock-market broker in 2007.
  - lotsofmangos 12y ago
    In terms of the limits of computer development, we have a way to go yet before we make something like a Matrioshka brain.
- deleted 12y ago
  [deleted]
lnanek2 12y ago
They say we can't get smaller than an atom, but electrons are smaller than an atom, and we don't even have to use just the charge but can also use properties like spin and momentum to get more values out of them. I.e. spintronics. Then of course there are photons as well. The article mentions itself that we use light for etching features even less than the wavelength of the light nowadays. Sometimes you need a big read-write head or something, but then you can just push magnetic domains past it on a wire, etc. so that isn't necessarily the size of piece of computation in the device if we move beyond transistors.
- Xcelerate 12y ago
  I agree with you there. It's not unreasonable to me that people might devise a way to push against the Planck limit in terms of the space that computation takes up.
DiabloD3 12y ago
The question I want to ask is, are generic CPUs now fast enough that people no longer need faster CPUs? I have an i7-4771 on my desktop (bought instead of 4770K because I wanted TSX... thanks Intel ;), and I can't really imagine much use for an even faster CPU unless I'm gaming or doing heavy compute work.
- userbinator 12y ago
  No, I don't think the things most people do with computers should require any faster hardware; the problem is that software is often being written to require increasingly more resources under the false assumption that processing speed and memory are "infinite" or close to it. The exponential growth that started many decades ago has promoted a culture of extreme waste. From the earliest notions of "premature optimisation", and the rise of structured programming and OOP with its many-layered abstractions, to the latest trend of ultra-high-level frameworks and the web-application movement, there is this constantly present notion that "abstractions and computing power is free, but programmer time is expensive". Although opposition to this seems to have increased in the recent years, it's still a prevalent attitude and being taught currently in many schools. People are being forced to frequently upgrade their hardware (with the associated waste and manufacturing costs) just so they can run the latest versions of software - often to do the same things at the same speeds they were doing them before. It's likely not too far of a stretch to say that software on average is now a few orders of magnitude larger and slower than it should be. This trajectory follows similarly to the early part of what happened to the car industry - fuel was initially cheap so manufacturers (and consumers) concentrated little on fuel efficiency, but starting in the 70s oil shortages made for some pretty rapid changes as people became aware that what they were doing was not sustainable. There has been much growth in interest in efficient hardware recently, which is good, but the other part of the equation, software, is also very important. Thus I think anyone who still believes in that mantra about programmer time, when working on software intended for a large number of users, is as absurd as someone in the car industry saying "engineer time is expensive, but fuel is cheap". Processors may be getting limited by the laws of physics but I don't think many programmers have reached the limits of their brainpower yet. :-)
  - 12y ago
bradshaw1965 12y ago
I love how the engineers in "Halt and Catch Fire" are always talking about "the laws of physics".
m_mueller 12y ago
Accelerator based computing is a tell that this is happening already. Shrinking everything down alone is not bringing the big speedups in performance-per-watt anymore, so what chip manufacturers do is putting as much ALUs as they can on the same die size, curbing lots of built-in management features in the process, that our software programming models have been built upon over the decades. Hardware is still getting faster at Moore's law, but only given constantly adapting software, i.e. "The Free Lunch Is Over"[1]. [1] http://www.gotw.ca/publications/concurrency-ddj.htm http://www.gotw.ca/publications/concurrency-ddj.htm
Jweb_Guru 12y ago
The answer to this question is yes. People like to talk about how the real issue is economics, not physics, but the inability to make chips much smaller economically is very much a reflection of physical constraints on the processes we're currently using to manufacture chips (particularly the lithographic process), and as of right now there's no clear successor to those processes that's going to enable them to get smaller for cheaper.
- wlievens 12y ago
  Isn't ASML still pursuing EUV?
tsotha 12y ago
Depends on exactly what you mean. You can keep adding cores until the cows come home. And I don't really buy the "we don't know how to use all those extra cores" argument. Multi-threaded code isn't the rocket science it's portrayed to be in the press. One thing that may become practical is die stacking, depending on what they can do about extra heat.
- badsock 12y ago
  Amdahl's law is a SOB: http://en.wikipedia.org/wiki/Amdahl%27s_law http://en.wikipedia.org/wiki/Amdahl%27s_law
  - tsotha 12y ago
    Except that's not how multiple cores are normally used.
agumonkey 12y ago
And now people are rethinking processor architecture : http://millcomputing.com/docs/ http://millcomputing.com/docs/
grondilu 12y ago
In June of this year HP announced its plan to build "The Machine". Regardless on how feasible their project is, I think they are right in pointing out that memory is the current bottleneck in computer engineering. We don't need faster processors. Focusing on the size of transistors, which are already insanely small when you think about it, may be a mistake.

74 points by ub 12y ago

Not even close, but there's good evidence they're pushing the limits of silicon transistors.

Right now, the laws of economics are a bigger problem than the laws of physics. Field effect transistors have been shown to work 5nm and even 3nm. However, the new lithography technologies needed to reach those resolutions cheaply are nowhere near ready.

idlewords 12y ago
I heard a rule of thumb that fab costs go up about 40% with each reduction in size. Is that accurate?
- _username_ 12y ago
  Intel paid ASML ~$4.1 billion to deliver 10nm lithography. That was ~ 1.5yrs ago (http://www.intc.com/releasedetail.cfm?ReleaseID=690165 http://www.intc.com/releasedetail.cfm?ReleaseID=690165). ASML stock is a good indicator what's happening in this business. Intel has running 14nm which is 16% better on SRAM cell than 16nm TSMC.
runeks 12y ago
> Right now, the laws of economics are a bigger problem than the laws of physics. The "laws of economics" and the "law of physics" are two sides of the same coin in this case. It's the laws of physics that prevents us from producing arbitrarily cheap chips, it's not two separate factors. The "laws of physics" are our hurdles, and the more we pass the cheaper the chips get.

Artemis2 12y ago

A metric that really puts things in perspective is the following: take a common consumer CPU, clocked at 3.4Ghz. That means it executes 3,400,000,000 cycles per second. Divide the speed of light by this number, and you obtain approximatively 0,088m. During the time your standard desktop CPU takes to finish a cycle, light only travels 9 centimeters.

_username_ 12y ago
Just a side not that light in other medium than air travels slower. It's not 300k km/h but ~200k km/h in FR4 microstrip (6"/ns where 1ns is equivalent to 1GHz clock).
- greenmountin 12y ago
  translated: "Just an aside: note that the speed that light travels in any medium is slower than it travels in vacuum. Its speed is no longer 3e8 m/s, but a third less in, for example, FR-4 microstrip (a popular prototype board dielectric). The effective speed is about 6 inches per ns, or at least, 6 inches per cycle of a 1 GHz clock."
bottled_poe 12y ago
I'm not really sure how that puts things into perspective. I actually have no concept of how fast photons are whizzing around the room.
- collyw 12y ago
  Takes light 8 minutes to get from the sun to here. (To put it in perspective.)
  - Artemis2 12y ago
    That's effectively how I see it: as a simple human, I consider light as an instantaneous phenomenon. Its speed seems to be the maximum attainable for about anything, but a man-made processor has the power to execute a simple computation in less time than what it takes for light to travel 9 centimeters. Isn't that impressive? Doesn't that cast doubt on how far we can improve our CPUs? Just remember that a thousand years ago, our beat creations were basically piles of rock.

hatethis 12y ago

No. Every single time someone supposes that any piece of technology is approaching its limits, the answer is no. Technology will continue to improve and advance as we make new discoveries. The simple fact is we do not know the future, so pretending like we know what things will be like in 20 or 50 years is just pointless. What's with this obsession of taking today's technological knowledge and assuming that things won't drastically change? Nobody should ever pretend to know what the future holds.

comboy 12y ago
Things will drastically change. But given piece of technology has its limits. Assuming it does not is like expecting horses to run faster than sound some time ago.
- charlieflowers 12y ago
  "If you immediately know the candlelight is fire, then the meal was cooked long ago."
saintgimp 12y ago
That's a very unreasonable point of view. Sure, it's true that in the past 200 years we've had an explosion of technological progress but there's absolutely no reason to assume that it's possible to continue it for an infinite amount of time. It's rather more likely that over time we'll discover the lines that separate "hard but possible" from "theoretically impossible given the physics of this universe". The only real question is when that will happen for any given area of technology. Asserting that technology will just continue to improve and advance forever simply makes you sound like a stock-market broker in 2007.
- lotsofmangos 12y ago
  In terms of the limits of computer development, we have a way to go yet before we make something like a Matrioshka brain.
deleted 12y ago
[deleted]

lnanek2 12y ago

They say we can't get smaller than an atom, but electrons are smaller than an atom, and we don't even have to use just the charge but can also use properties like spin and momentum to get more values out of them. I.e. spintronics. Then of course there are photons as well. The article mentions itself that we use light for etching features even less than the wavelength of the light nowadays. Sometimes you need a big read-write head or something, but then you can just push magnetic domains past it on a wire, etc. so that isn't necessarily the size of piece of computation in the device if we move beyond transistors.

Xcelerate 12y ago
I agree with you there. It's not unreasonable to me that people might devise a way to push against the Planck limit in terms of the space that computation takes up.

DiabloD3 12y ago

The question I want to ask is, are generic CPUs now fast enough that people no longer need faster CPUs? I have an i7-4771 on my desktop (bought instead of 4770K because I wanted TSX... thanks Intel ;), and I can't really imagine much use for an even faster CPU unless I'm gaming or doing heavy compute work.

userbinator 12y ago
No, I don't think the things most people do with computers should require any faster hardware; the problem is that software is often being written to require increasingly more resources under the false assumption that processing speed and memory are "infinite" or close to it. The exponential growth that started many decades ago has promoted a culture of extreme waste. From the earliest notions of "premature optimisation", and the rise of structured programming and OOP with its many-layered abstractions, to the latest trend of ultra-high-level frameworks and the web-application movement, there is this constantly present notion that "abstractions and computing power is free, but programmer time is expensive". Although opposition to this seems to have increased in the recent years, it's still a prevalent attitude and being taught currently in many schools. People are being forced to frequently upgrade their hardware (with the associated waste and manufacturing costs) just so they can run the latest versions of software - often to do the same things at the same speeds they were doing them before. It's likely not too far of a stretch to say that software on average is now a few orders of magnitude larger and slower than it should be. This trajectory follows similarly to the early part of what happened to the car industry - fuel was initially cheap so manufacturers (and consumers) concentrated little on fuel efficiency, but starting in the 70s oil shortages made for some pretty rapid changes as people became aware that what they were doing was not sustainable. There has been much growth in interest in efficient hardware recently, which is good, but the other part of the equation, software, is also very important. Thus I think anyone who still believes in that mantra about programmer time, when working on software intended for a large number of users, is as absurd as someone in the car industry saying "engineer time is expensive, but fuel is cheap". Processors may be getting limited by the laws of physics but I don't think many programmers have reached the limits of their brainpower yet. :-)
- 12y ago

bradshaw1965 12y ago

I love how the engineers in "Halt and Catch Fire" are always talking about "the laws of physics".

m_mueller 12y ago

Accelerator based computing is a tell that this is happening already. Shrinking everything down alone is not bringing the big speedups in performance-per-watt anymore, so what chip manufacturers do is putting as much ALUs as they can on the same die size, curbing lots of built-in management features in the process, that our software programming models have been built upon over the decades. Hardware is still getting faster at Moore's law, but only given constantly adapting software, i.e. "The Free Lunch Is Over"[1]. [1] http://www.gotw.ca/publications/concurrency-ddj.htm http://www.gotw.ca/publications/concurrency-ddj.htm

Jweb_Guru 12y ago

The answer to this question is yes. People like to talk about how the real issue is economics, not physics, but the inability to make chips much smaller economically is very much a reflection of physical constraints on the processes we're currently using to manufacture chips (particularly the lithographic process), and as of right now there's no clear successor to those processes that's going to enable them to get smaller for cheaper.

wlievens 12y ago
Isn't ASML still pursuing EUV?

tsotha 12y ago

Depends on exactly what you mean. You can keep adding cores until the cows come home. And I don't really buy the "we don't know how to use all those extra cores" argument. Multi-threaded code isn't the rocket science it's portrayed to be in the press. One thing that may become practical is die stacking, depending on what they can do about extra heat.

badsock 12y ago
Amdahl's law is a SOB: http://en.wikipedia.org/wiki/Amdahl%27s_law http://en.wikipedia.org/wiki/Amdahl%27s_law
- tsotha 12y ago
  Except that's not how multiple cores are normally used.

agumonkey 12y ago

And now people are rethinking processor architecture : http://millcomputing.com/docs/ http://millcomputing.com/docs/

grondilu 12y ago

In June of this year HP announced its plan to build "The Machine". Regardless on how feasible their project is, I think they are right in pointing out that memory is the current bottleneck in computer engineering. We don't need faster processors. Focusing on the size of transistors, which are already insanely small when you think about it, may be a mistake.