3 ms·

> a TWh, which is about six million years' of power i'm not a physics guy but wanted to check this - a Watt is a per second measure, and a Terawatt is 1 trilli

by swyx 4y ago

> a TWh, which is about six million years' of power i'm not a physics guy but wanted to check this - a Watt is a per second measure, and a Terawatt is 1 trillion watts, so 1 TWh is 50 billion seconds of 20 Watts, which is 1585 years of power for a single brain, not 6 million. i'm sure i got this wrong as i'm not a physics guy but where did i go wrong here? a more neutral article (that doesn't have a clear "AI is harming our planet" agenda) estimates closer to 1404MWh to train GPT3: https://blog.scaleway.com/doing-ai-without-breaking-the-bank-yours-or-the-planets/ https://blog.scaleway.com/doing-ai-without-breaking-the-bank... i dont know either way but i'd like as best an estimate as possible since this seems an important number.

belval 4y ago
A watt is not a per-second measure, Wh are the energy measurement to W being the power. TWh = 10^12Wh which means a trillion-watt for 1 hour. 10^12 / 20 (power of brain) / 24 (hours in a day) / 365 (days in a year) = 5 707 762 years.
- pfdietz 4y ago
  One watt is one joule per second. What exactly do you mean by "a per-second measure"?
  - belval 4y ago
    The seconds are not a denominator, OP was doing TWh / W as if W = 1 / 3600 * Wh which is not the case.
primis 4y ago
Watts are actually a time independent measurement, note that the TWh has "hour" affixed to the end. This is 1 Tera Watt over the course of one hour, not one second. Your numbers are off by a factor of 3600. 1TWh / 20 Watt brain = 50,000,000,000 (50 Billion) Hours. 50 Billion Hours / (24h * 365.25) = 5,703,855.8 Years
- swyx 4y ago
  thank you both.. was googling this and found some stackexchange type answers and still got confused. apparently it is quite common to see the "per time" part of the definition of a Watt and get it mixed up with Watt-hours. i think i got it now thank yoyu
  - TeMPOraL 4y ago
    It is. The main culprit, arguably, is the ubiquitous use of kilowatt hours as unit of energy, particularly of electricity in context of the power company billing you for it - kilowatt hours are what you see on the power meter and on your power bill.
  - jeffbee 4y ago
    If you’re going to reinterpret watts on one side you have to do it on both sides. So, by your thinking, which is not wrong, 1h*1TJ/s vs 20J/s. As you can see, you can drop J/s from both sides and just get 1/20th of a trillion hours.
- gnfargbl 4y ago
  Thanks for explaining the calculation! There is a huge error though, which is that I mis-read the units in the second link I posted. The actual power estimate for GPT-3 is more like 1 GWh (not 1TWh), so about 6000 years and not 6 million...!
  - swyx 4y ago
    lol, this is more like the other estimate’s ballprk… 1 TWh sounded way off and i was like “wait i gotta check this”
    - gnfargbl 4y ago
      Yeah, the other thing that I should have noticed was the completely unreasonable cost of 1 TWh of energy. If 1 kWh cost about $0.15 at the time they trained the model, 1TWh would have been like $150M. Probably twice that after accounting for cooling. Doh.

by swyx 4y ago

belval 4y ago

A watt is not a per-second measure, Wh are the energy measurement to W being the power. TWh = 10^12Wh which means a trillion-watt for 1 hour. 10^12 / 20 (power of brain) / 24 (hours in a day) / 365 (days in a year) = 5 707 762 years.

pfdietz 4y ago
One watt is one joule per second. What exactly do you mean by "a per-second measure"?
- belval 4y ago
  The seconds are not a denominator, OP was doing TWh / W as if W = 1 / 3600 * Wh which is not the case.

primis 4y ago

Watts are actually a time independent measurement, note that the TWh has "hour" affixed to the end. This is 1 Tera Watt over the course of one hour, not one second. Your numbers are off by a factor of 3600. 1TWh / 20 Watt brain = 50,000,000,000 (50 Billion) Hours. 50 Billion Hours / (24h * 365.25) = 5,703,855.8 Years

swyx 4y ago
thank you both.. was googling this and found some stackexchange type answers and still got confused. apparently it is quite common to see the "per time" part of the definition of a Watt and get it mixed up with Watt-hours. i think i got it now thank yoyu
- TeMPOraL 4y ago
  It is. The main culprit, arguably, is the ubiquitous use of kilowatt hours as unit of energy, particularly of electricity in context of the power company billing you for it - kilowatt hours are what you see on the power meter and on your power bill.
- jeffbee 4y ago
  If you’re going to reinterpret watts on one side you have to do it on both sides. So, by your thinking, which is not wrong, 1h*1TJ/s vs 20J/s. As you can see, you can drop J/s from both sides and just get 1/20th of a trillion hours.
gnfargbl 4y ago
Thanks for explaining the calculation! There is a huge error though, which is that I mis-read the units in the second link I posted. The actual power estimate for GPT-3 is more like 1 GWh (not 1TWh), so about 6000 years and not 6 million...!
- swyx 4y ago
  lol, this is more like the other estimate’s ballprk… 1 TWh sounded way off and i was like “wait i gotta check this”
  - gnfargbl 4y ago
    Yeah, the other thing that I should have noticed was the completely unreasonable cost of 1 TWh of energy. If 1 kWh cost about $0.15 at the time they trained the model, 1TWh would have been like $150M. Probably twice that after accounting for cooling. Doh.