enter image description here

This image purports that you can measure data in grains of rice - one byte being one grain of rice and one gigabyte then being three container lorries.

Byte of data   : one grain of rice
Kilobyte       : cup of rice
Megabyte       : 8 bags of rice
Gigabyte       : 3 container lorries 
Terabyte       : 2 container ships
Petabyte       : covers Manhattan
Exabyte        : covers the UK (3 times)
Zettabyte      : fills the pacific ocean 

Are these measurements accurate?

  • 4
    Is this a notable claim? It seems like just an illustration. Many of the items are very imprecise. How big is a "bag" of rice?
    – user11522
    Jun 10 '16 at 11:09
  • 4
    I dont see how anyone is going to answer this without resorting to back-of-the-envelope calculations, which will almost certainly be Original Research
    – Jamiec
    Jun 10 '16 at 11:27
  • 7
    "This image purports that ou can measure data in grains of rice". That's not it. They are not using rice as a unit to measure data. They're just using an comparaison where 1 grain ou rice = 1 byte to illustrate how big Gigabytes, Terabytes, etc are. Jun 10 '16 at 12:10
  • 4
    Covers Manhattan and the UK to what depth? This claim is not nearly accurate enough to prove/disprove either way, there is too much left to interpretation. Jun 10 '16 at 12:24

The rice here is an analogy, not an actual way to measure data

If you do a search for "David Wellman Myriad Genetics presentation", you can easily find a link to the presentation he gave, though this particular image comes from a different presentation. Wellman's presentation was about "Big Data", the term used in reference to companies trying to figure out how make sense of the massive amounts of data they have, often terabytes or petabytes of it.

This image purports that you can measure data in grains of rice

That's not what the image is talking about - rice is being used here as an analogy. Thanks to better manufacturing, computers have been getting smaller even while the data they store has been increasing, so it's easy to hear "one terabyte" and not really understand the scale of how much data there is. Wellman was trying to help his audience understand the scale of problem.

For example, suppose a company has a petabyte of data that they are wanting to extract useful information from. To understand the scale of this problem you can think of it as if they were trying to search through a rice-covered Manhattan in order to find the information they need.

If you're still wondering about how accurate the numbers are, let's pull some numbers from Wikipedia's Orders of magnitude (volume) page to get numbers for the first two points (volumes are in cubic meters):

7×10−8 Volume of a large grain of rice 3 mm wide by 12 mm long

4.73×10−4 One US liquid pint

7×10-8 times 1000 is 0.7×10-4, while one cup (half of a pint) is 2.36×10-4. It's not perfect, but it's close enough for us to assume that either (1) the author used slightly different numbers or (2) the author didn't care about perfect accuracy.

Looking at another pair, Manhattan covers 59.1 km2 of land, while the UK covers 240,000 km2 of land. Here the numbers are a little off - the UK covers about 4000x the area of Manhattan, so unless Manhattan was actually being covered 12 times, the UK would not actually be fully covered three times.

In both of these cases, it doesn't matter that the numbers might be a little off - rice is being used as an analogy so perfect accuracy isn't necessary.

  • It seems like every time someone tries Original Research, they make dubious assumptions, justifying why we don't permit it. (1) Why a large grain of rice? Small grains are also listed on that page. (2) Rice does not perfectly pack into a space, so you can't just multiply the volume of a single grain. (3) The choice of 1000 over 1024 needs to be defended.
    – Oddthinking
    Jun 11 '16 at 4:39
  • 3
    @Oddthinking my point is that it's in the correct ballpark. Because it's being used as an analogy, it doesn't matter that the numbers don't quite match up. As such, I didn't think it would just distract from that point if I went into the details of why large grain instead small, packing, and 1000 vs 1024.
    – Rob Watts
    Jun 11 '16 at 4:52
  • You can't argue that their calculations are imprecise by doing even less precise calculations yourself. Individual rice grains, according to your source, range from 2-7 ×10^−8 m^3 (which is itself probably meaningless, because rice grains can be preprocessed in different ways), so inappropriately multiplying it by 1000 - as you do - exactly covers your definition of a cup (which itself is poorly defined. 1 US cup = 236mL. 1 metric cup = 250 mL.)
    – Oddthinking
    Jun 11 '16 at 7:25
  • 1
    Whether this answer is correct or not, it's still original research. While Oddthinking tried to point out some issues as examples, debating those is not the issue. The issue is that the form of this answer is unacceptable. There some hints here on how to fix this (back-of-the-envelope calculations). In short: find a reputable expert in the field making the calculations for you, do not attempt them here.
    – Sklivvz
    Jun 11 '16 at 9:12
  • @Sklivvz how's it look now? I tried to make the focus more on how the rice is being used as an analogy and have the calculations just be supplemental.
    – Rob Watts
    Jun 14 '16 at 16:31

Not the answer you're looking for? Browse other questions tagged .