- Primality test challenge
- Trial division
- What is computer memory?
- Algorithmic efficiency
- Level 3: Challenge
- Sieve of Eratosthenes
- Level 4: Sieve of Eratosthenes
- Primality test with sieve
- Level 5: Trial division using sieve
- The prime number theorem
- Prime density spiral
- Prime Gaps
- Time space tradeoff
- Summary (what's next?)
What is the limit of computer memory? Created by Brit Cruise.
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- 5:17"Will we ever be able to store a bit on something smaller than an atom?" What do you think?(46 votes)
- One of many theoretical possibilities I could think of include:
electrons are smaller than atoms, and it would be plausible to store information stored as the excitation state of an atom,
read by : detecting the photon emitted upon decay to a less excited state
(we need to send a photon back to the atom matching change in energy to put electron back in the original state before reading)
write by: allow excitation state to decay to unexcited state, then use a photon of the desired value to excite atom
There are several excitation states of an atom, thus one could use this to store several bits on an atom.
Now the big question is: Why would we want to ?
There was a time in computing when storage was extremely precious. Storing even one full length movie on a computer in the 80s would be impossible for most people.
Times have changed.
We are rapidly approaching an era where our ability to store data exceeds our ability to generate data we want to store. Already, the average computer hard drive can easily store text versions of all of the books in a library. However, no person could ever read all of these books. The time where an average computer could store high def copies of all the movies ever made, is not far away.
This is all achievable with semi conductor technology which is on a scale much larger than atoms.
When we reach the point where we can easily store more data than we can reasonably want to (within a desired size for the storage device) , researchers will likely stop expending effort on ways to pack more data into a smaller space. We will reach this point long before we reach the size of 1 bit/ atom.(71 votes)
- besides any other importance on DNA storage, which there probably are quite a few,
DNA storage would still occupy more space that 1 bit/atom storage, right?(4 votes)
- 5:17"Will we ever be able to store a bit on something smaller than an atom?" This is a bit of a far-fetched idea but in the future, we could possible store memory in something like a theoretical dimensional locker.(6 votes)
- The way our society is going now who knows what we will able to do in the next 50 years, maybe 25, or even 5 to 10 years!! WHO KNOWS?!(3 votes)
- An atomic hard drive would still have moving parts, right? Will that level of memory capacity ever be possible on a Solid State Drive?
I'd love a video on SSDs.(6 votes)
- As computers get smaller we are creating more and more memory in each device, is it possible to merge these small devices into one giant device with a huge memory?(4 votes)
- He seemed so excited about atomic storage:4:12"a single ATOM". Proper reaction.(4 votes)
- That is a big deal. Imagine fitting every single video on Khan Academy into something the size of a penny! Right now it takes several gigantic servers!(4 votes)
- Starting at4:30, when the video discusses the possibility of handheld "super drives," even if we were able to store data on what would be an atomic level, would there be any way to prevent corruption of data if say, you dropped the hard drive?(3 votes)
- will it even be possible in the future to fit a 1000 things in a atom and if it where how would it happen isn't that going to be crazy when some one does find out a way to fit that many in I don't see how its possible I know lots of smart people but all there brains put together I still don't think its possible if any one answers me I will be great ful(3 votes)
- 4:35How long is the estimated time before something the quality of the super drives could exist?(3 votes)
- When did computer science come into history before today?(3 votes)
Voiceover: When we perform calculations with a pen and paper, we often need to save intermediate results. And we may do this with, say, scrap paper, and in this case, the paper is acting as a form of external memory. And memory no matter the form, takes up physical space. Computers contain memory, we can think of it as the scrap paper for the computer. And, say, when you construct an array to store values in your program, you require memory. And, at the lowest level, computers read and store all instructions as a string of numbers. But, how do you store numbers in a machine? This was a very difficult problem originally, especially when you need computers to hold their memory after the access to power is lost. This is known as nonvolatile memory. The easiest difference for a machine to detect is simply a presence versus an absence of something. And this is how old punch cards would work. Along the top, we have some data and the vertical columns contain a series of punched holes which represent each character. So, computers really have 2 fingers, base 2, same as a light switch being "on" for 1, and "off" for 0. This is the smallest amount of information, a single difference, which we call a bit. But bits are powerful for storage because the amount of unique states grows exponentially as we add bits together. Remember, one light switch is one bit and it can store 2 states, but 2 light switches can store 4 unique states. And 8 light switches or 8 bits can store 256 unique states. And space is measured in bits, but the physical size of a bit depends on your method of storage. So how do computer store zero's and one's internally? (gentle music) Man in Uniform: Modern data processing systems like these use thousands of magnetic cores. What are magnetic cores? They are tiny rings of nickel alloy or other magnetic materials. They have replaced vacuum tubes for many important functions in data processing systems. Voiceover: And it allowed computers to store bits as clockwise versus counter-clockwise magnetization direction. Because the each core could be magnetized in 2 different ways, depending which direction the current was applied. Man in Uniform: Because a bit can be represented by any bi-stable device and a magnetic core is a bi-stable device. Voiceover: Later on, this was done using thin film magnetic disk where we can think of as each bit as a tiny magnetic cell, which can be charged to store either a 1 or a 0. So, long story short, the size of a bit has been rapidly shrinking since the days of punch cards. A hard drive in a modern computer can be thought of as billions of tiny magnetic cells. Now, you may wonder, well how small can these little magnetic cells be? And current research at IBM is pushing this to the atomic level where they have shown 12 iron atoms can work together as a stable magnetic unit, where they are able to store a 1 or a 0, depending how they are oriented. And this is approaching a theoretical limit where we would hold a single bit on a single atom! And interestingly, IBM estimates that we can put around one quadrillion bits of information in a handheld device, the size of an Ipod, with atomic storage. And, let's call this a super drive, it doesn't even exists yet, as a hypothetical example. A small handheld super drive using atomic storage would hold one thousand terabits, which is one thousand trillion switches or more commonly known as 125 terabytes in the palm of your hand, or to use an example everyone can understand, 125 terabytes is the same as having a 1250 kilometer long book shelf in the palm of your hand. And this is what the future of memory looks like, or we ever be able to store a bit on something smaller than an atom?