## Monday, 25 February 2019

### More Basic Cryptography

First of all it might be an idea to explain some of the jargon that is used in cryptography (though some are probably pretty obvious):
• Plain Text: This is the normal, readable, text.
• Cypher Text: This is the plain text that has been encrypted. Normally it cannot be read, or if it can be read it usually takes some effort.
• Encrypt: To turn the plain text into cypher text.
• Decrypt: To turn the cypher text into plain text.
• Key: The function that is used to encrypt or decrypt a message.
• Symmetric Key: Where the same key is used to decrypt or encrypt a message.
• Public/Private Key: Where different keys are used to encrypt or decrypt a message.
• Public Key: A key that is known to everybody. Normally used to encrypt a message, but is also used to validate a signature.
• Private Key: A key known only to the holder. Normally used to decrypt a message, but also used to create a signature.

### Symmetric Key Cryptography

As mentioned above, symmetric key cryptography is where the key that is used to encrypt and decrypt the message is the same. We saw that in the previous post where we were looking at the Caeser cypher and also looking at the double transposition cypher. However, this is also used in other areas, and the one we will be looking at here is known as the 'one-time pad'.

The 'One-Time Pad' is where the key is used once, and once only, and is then discarded. When it comes to using it with computers, basically what we need to do is to convert the letters into numbers, and then XOR the numbers with the key to create the cypher text. The message is then passed on to the other side, where the key is used to decrypt the message. The key is then discarded. The following diagram may help you understand how this works:

Another idea we need to know, an idea that arose from one of my previous subjects, is the XOR. The XOR function is one of the boolean functions where if you XOR the same number (0 or 1) it will produce a 0 and if you XOR different numbers it will produce a 1. Now, I asked whether you could use other functions as well (OR, NOR, AND, NAND) but I really didn't get any answer to that, except for the statement that we use XOR. I'm not really sure, but to be honest, I don't see why we couldn't, but I guess we just use the XOR function because that is the way that they have always done it. Anyway, here is a table that better explains the XOR:

So, let us see it in operation. We have the message 'Attack Sparta' which we want to encrypt. So, using the one time pad, we convert the letters into binary using a code that only we know, and then we spew out a series of numbers which we then use the XOR operator which will produce another series of numbers. Using our code, we then convert the numbers back into letters, which produces the message "tlklkkrttacl'. The table below will show how we came to that:

Now, another interesting thing is that by interposing a different key we may even be able to produce a completely different message. Take the following for example:

Here we have a message, heil Hitler, being encoded, and by using the same key, we have basically decrypted it to produce the same message. However, what if we use a different key?

Well, it seems like we have a completely different message. Actually, you could even have it come out completely garbled, but that would probably defeat the purpose. Similarly if the message came out as 'Strawberries and Pancakes'. Honestly, why would anybody be wandering around with a coded message that says 'Strawberries and Pancakes'. It would sort of raise some alarms.

Now, the stream cypher is what is known as being 'provably secure'. This means that it is accepted that this form of encryption is basically secure. Now, we have absolutely no information about the message from the cypher text. In fact all plain text messages are equally likely, though for this to work the key must be used once, and only once, and is only known to the sender an the receiver. However, there is one exception - the length of the cypher text and the plain text is the same. Further, the key will also need to be as long as the message, which can also create problems, particularly with computer systems. For instance, a 2 GB message will need a key that is also 2 GB in length.

There is another problem - if you know both the cypher text and the plain text then you can easily work out the key. However, since they key is used only once, and if you already know both messages, then I'm not entirely sure why it is that you would also want to know the key. This is known as a plain-text attack.

So, let's consider some uses for this one time pad. Well, we've already seen one, but the above diagram, which was taken from my lecture notes, shows another use which is called a stream cipher. Basically a stream cipher is where a series of pseudo-random bits are generated to encode the message. In fact the message is encoded bit by bit, and the stream is only used once, and then discarded. I say pseudo-random because anything generated by a computer simply is not going to be random. This system is even used today in modern computers, due to the pseudo-random nature of the cipher. However, as mentioned above, the stream cipher is still as long as the message, which means it doesn't offer absolute security, and it also has the potential of taking up quite a lot of space (not to mention the problem of actually getting the key to the other party).

The next concept we have is the block cipher, where a block of plain text is encrypted using a deterministic key. Now, the difference is that the key is not necessarily as long as the block of plain text, and the entire block is encrypted with the key as opposed to the stream cipher where the bits are encrypted one by one. Now, when we have multiple blocks that are identical, the encrypted previous block is actually added to the new block, which then creates a completely different block, and this new block is then encrypted. With the first block, a random vector is generated and added to the block before it is encrypted. Hopefully another diagram from my lecture notes will help explain this:

However, there is one very big problem when it comes to symmetric key encryption, and that is actually exchanging the keys. You see, it is all well and good generating random, one time keys, however if there is no way to actually pass that key on to the recipient using a secure channel, then the whole concept basically hits a brick wall. There is a solution, but before we get to that, let's look as hashes.

### Hash Functions

So, now we come to this concept known as the hash. A hash could be defined as being a digital digest of a computer file. Basically, what happens is that when you 'hash' a document, or something else, it will produce a number, usually in hexadecimal, of a pre-determined length. In fact each and every one of those hashes are of exactly the same length. So, let us create a simple document that says 'I woz 'ere'.

Before I continue I will point out that the following instructions are for a Linux command line terminal (which is basically the same for the Apple Mac). However, for Windows it is slightly different, and I also believe you have to download and install other software - this is one of the many reasons that I really don't like Windows.

Anyway, to generate the hash of the document you use the command 'md5sum' and the name of the document you wish to hash. In this instance:

md5sum document.txt

produces the following hash:

Now, let us hash a pdf of Hamlet Prince of Denmark:

md5sum hamlet.pdf

So, we have two documents of completely different sizes producing a hash that is exactly the same length. However, there is another function of the hash that is very interesting. Let us change 'I woz 'ere' to 'I was here':

aa126cf8d527030d92bc88c729b2beb1

Wow! Have a look at that. we changed one letter and all of a sudden the entire hash has changed. In fact let us change the ' to a " and see what happens.

6de00a205c2046a4ea262756308321e5

Yep, once again the entire hash has changed.

So, let us convert the hashes into binary, and have a look at what values have changed. Since they are ridiculously long, I have broken them down into 32 bits each, with the first message being the top, and the second message being the bottom. I'm sure you can see for yourself have much a single letter has changed the entire value.

10111001000111011111000001111011
00101001101100101011111010110001

01000000101001010010111101010000
10010010101111001000100011000111

01011100110110011011111100111111
11010101001001110000001100001101

1111011010101111010110100100110
10101010000100100110110011111000

Now there is something very, very, very useful with that, namely checking the validity of a document, or a file. In fact if you go to the Kali Linux website you will note that next to each of the files there is what is known as an sha256sum. Let us download one of the files (which will take a but of time, and then hash it using the sha256 algorithm. So, the hash on the website is:

61bc17ee83ffa12e674af35503181bb336e943ccefac90805807f4bf0137e4b2

Now let us hash the file:

61bc17ee83ffa12e674af35503181bb336e943ccefac90805807f4bf0137e4b2

Well, as we can see the hashes are the same, which means that the file that I downloaded was the file that I wanted to download.

So, the reason for this is that we are using the hash to make sure that the file that we have downloaded is the same as the file on the website. This is particularly useful when we are downloading the file from a completely different site, such as a mirror. In fact it is very useful to make sure that the file we have downloaded is what we want and not, say, some trojan horse, or some virus that is designed to completely melt your CPU.

The other thing about the hash is that the conversion is one way. This isn't like an encrypted message where we have a key to decrypt it - once a message has been hashed, there is no way of being able to reconstruct the message from the hash. Does that nullify it's usefulness - well, not quite, but we will get to that shortly because there is another problem with hashes, and that is collision.

Basically a hash collision is where two completely different messages produce exactly the same hash. Now, since the MD5 hash, which is 128 bits, can have 3.4 x 1038 different hashes, which is something along the lines of 340,282,366,920,938,463,463,374,607,431,768,211,456 different combinations, it is unlikely that there will be a collision, though it is still a distinct possibility. In fact a program has been written to verify the chances of hash collisions without going through every possible combination (known as a brute force technique).

Now, there are numerous uses for the hash, and one that is pretty much used everyday is passwords. Basically your password isn't stored in a server as a password, but as a hash (though not all websites actually do this, and as such I would be very wary of such sites). So, when you enter your password details, the encrypted password is sent to the server, hashed, and is then compared with the hash that is stored there. A match will grant you access. This is the main reason why, if you forget your password, IT won't be able to retrieve it for you, namely because nobody, other than you, knows what the actual password is.

Another use is in what is called a closed auction. What happens is that when the bids are made the bids are hashed, and thus only the bidder actually knows what they had bid. However, there is a slight problem with that namely because a rather unscrupulous person, who knows the range of the bids, can basically generate a hash for each of the numbers in that range and then work out what the other participants' bids are. There is a way of solving this though, and that is by salting the hash. You know how by changing a single character will dramatically change the actual hash. Well, you can do that with the bid by adding a word, such as 'puppy dog', that only the bidder knows, so that the bids are sealed even further.

One final use for the hash is through spam reduction, which is a similar method that is used with proof of work for bitcoin (which we will look at later). Basically this method makes it much more difficult for bulk emails to be sent. To send a bulk email, a hash needs to be generated that starts with a certain number of 0s. The more 0s that are required, the greater amount of work that is produced. This does change the dynamics because there was a time when sending out bulk emails was very, very cheap. However adding a proof of work to the process means that this is no longer the case.

More Basic Cryptography by David Alfred Sarkies is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. This license only applies to the text and any image that is within the public domain. Any images or videos that are the subject of copyright are not covered by this license. Use of these images are for illustrative purposes only are are not intended to assert ownership. If you wish to use this work commercially please feel free to contact me

## Wednesday, 20 February 2019

### Es ist kaput - Equipment Failure

Let me begin by telling you a couple of stories. The first involved a hard drive that I was using while I was out and about in South-East Asia. One day I plugged it into my computer and all of a sudden the computer refused to read it. I was rather frustrated because it meant that I had pretty much lost a whole heap of stuff. Fortunately for me there was a backup so the amount of stuff that I had lost wasn't all that much (I was actually carrying two hard drives on me, just in case of that eventuality). Anyway, it turned out that it's failure was purely my fault. I hadn't been treating it kindly, and also had the habit of pulling it out without bothering to unmount it. It turned out that the head had buckled and basically that was that - everything was gone.

Oh, and before I continue, just a quick video explaining why you should always unmount your devices before pulling them out:

Also on that same trip, when I was in Phuket, I purchased a hard drive from a computer shop in a shopping center (never buy hardware from one of the roadside stalls, you can be guaranteed that they will not work - a guy I was talking to in Hong Kong had did just that with a flash drive, and when he discovered that it wasn't working he opened it up to discover that there wasn't actually any interior). Anyway, I attempted to format this hard drive for Linux, and also to encrypt it, and everything I did caused the Hard drive to simply ceased to exist. Honestly, I still don't know what the problem is, but my Dad eventually got it working. The third harddrive I bought in Bangkok is still working now.

The final story involved a 3 TB harddrive that I purchased in Melbourne, and I basically copied all my movies onto it. Anyway, after two weeks that hard drive also went kaput. Fortunately my Dad was around and he managed to pretty much rescue everything, but he proceeded to tell me that the hard drive had pretty much bitten the dust and it was basically useless. I ended up having to purchase myself a new one.

Anyway, as you can tell, equipment will eventually break down, and there are three types of equipment failure: wear out failure, random failure, and infant mortality failure. Basically the chance of wear-out failure increases as time goes on, but it is actually possible to work out the chances of when such an item will fail (which I will get to) - this could be said is what happened in my first example. The second one, as you can guess, pretty much happens at anytime, and the causes are, well, completely random. As it turns out, that was what happened in my third example. The reason it isn't infant mortality failure is because that pretty much happens when it fails the moment you open the package - you could say that this is what the second example (or at least the experience of my friend in Hong Kong, but I suspect that has more to do with him being ripped off as opposed to any inherent fault with the device, but then again, not having any insides could be considered a form of failure).

Anyway, you can graph these types of failures, and when you combine them they produce what is called a 'bathtub curve' namely because it is shaped like a bathtub:

Honestly, there is probably little one can do with regards to random failure. Sure you can purchase extended warranties, and in fact a lot of devices come with warranties as is, and if it does fail within the period of the warranty, then I would certainly recommend calling on the warranty. For wear-out failure, well, that is always going to happen - the second law of thermodynamics sort of attests to that. However, one way of dealing with it is by making sure that wear-out failure only occurs around the time when we are basically going to be throwing the thing out anyway due to obsolescence. As for infant mortality, well, manufacturers now run stress tests on their devices to make sure that they can detect such failures, and then toss out such devices before they actually reach the market.

Now, like pretty much everything where electronic components are concerned, there is another value we need to take into consideration, and that is the Mean Time Between Failure (or MTBF). Now, this is the arithmetic mean which means that this is generally the case, but there will be devices that last longer, and others that don't, and it certainly doesn't mean that this is how long your device will last until it goes kaput (and it certainly won't go kaput the second that its usage goes over the MTBF). Anyway, say a hard drive has a MTBF of 57 years (or 500,000 hours) - this means that of 1000 drives, half will last longer, and half will last shorter. In another way, if you divide 500,000 by 500 you get 1000 hours, which is 41 days, which means that out of those 500 drives, you can expect one to bite the dust every 41 days.

 This is a bit of an extreme example

Let us have a look at some of the components that make up a computer and see how failure can be an issue:

Capacitor: Now, capacitors are one of the five basic electronic components (transistor, resistor, inductor, and diode are the others) and they basically store electricity, albeit for a short period of time. They are generally used to smooth out electrical flow, or to induce delays, though they also make up the computer's RAM. In the older days (that is pre-2000s) capacitors had the tendency to leak, corrode, or even burst, and that could cause problems in your system. However, these days they are much more reliable, and generally are able to withstand a lot more than they used to.

Cooling Fan: This has moving parts, so you can be assured there is always going to be a chance that this will bust. Once again, quality does do better with price, though fortunately if your cooling fan fails the computer will probably shut down prior to there being any permanent damage done to your system. However, we do need to make sure that it is configured problem because there is the issue, particularly with tower cases where the motherboard is sitting vertically, that if it, or the heatsink, isn't secured properly it could become lose, or even fall off. Also, having enough space in the case to allow good airflow also helps.

Power Supply: I had a power supply fail on me once, and I was forced to actually fix it myself. Fortunately I had the laptop to assist me which meant that not only did I still have a working computer, but I could also look up the solution on the internet. Anyway, power supplies tend to last between 5 to 10 years before giving up the ghost, but can also be affected by things like surges, lighting strikes, brownouts, and dust. Basically make sure that you aren't maxing out the power usage with your equipment, and certainly don't buy junk. Keeping it free from dust also helps.

Hard Drives: If there is one thing that I would recommend, and that is always unmount them before unplugging them from the machine. Hard drives, being mechanical, are always going to be subject to wear and tear, but there is also the chance of head crashes, which can completely destroy them and everything on it. I would recommend not treating them roughly, and making sure the head is parked before moving it.

Optical Drives: Honestly, the same goes with these as it does for hard drives - to an extent. Being mechanical, and having moving parts, they are going to wear out. Also, be careful that the laser doesn't get dirty because if it does then, well, it isn't going to work. The opening mechanism could also fail, meaning you are stuck with a dud device. However, these really aren't in use anymore, particularly with digital download technology such as Spotify, Netflix, and Steam. Optical disks have basically gone the way of the sextant.

One way of dealing with problems with drives, particularly hard drives, is what is termed as SMART technology.

#### The SMART Harddrive

SMART stands for Self-Monitoring-And-Reporting-Technologies (how long did they take to come up with that one I wonder?) and is basically designed to work out if there is something wrong with the hard drive, and find a work-around for it. For instance, if there are bad sectors on the drive, the SMART will remember where those bad sectors are and basically avoid them. SMART technologies also work with the operating system to inform you of any problems as well. So, let us take a look at some statistics that it takes into account with regards to determining whether a hard drive is functional or not:

Spin-Up-Time: This is basically the time the hard drive takes to go from a stationary state to the state where it is fully spinning. Obviously if it is taking longer then the drive is starting to wear.

Bad Sector Count: The number of bad sectors that are on the drive. Obviously the higher the number, then the worse the drive is. The more bad sectors, the less space there is on the drive for you to be able to store all of those pictures (yes, you know the ones I'm talking about).

Power On Hours: This is basically the total number of hours that the hard drive has been operational. Probably something that you should be paying attention to considering what we have been speaking about previously.

Power Cycle Count: This is the total number of times that the drive has been turned on, and turned off again.

Spin Retry Count: If the initial spin failed then this counts the number of retries the disk has performed to get up to full speed. Obviously if the drive is starting to fail in this regards then maybe it is time to start looking for a new drive.

Seek Performance Time: This is basically the time it takes for the drive to perform seek operations, namely to attempt to find that saucy picture you have hidden away in your sub directories. If this value is increasing then this may be signs of mechanical wear.

#### Going on a RAID

RAID stands for 'Redundant Array of Independent Disks' and is basically a bunch of hard drives connected to each other so that they function as a single disk. These are used in a lot server systems, namely because the average consumer simply isn't going to have so much data that they will need a RAID configuration, unless, of course, you happen to be running a a successful Youtube channel, such as this guy:

Yeah, basically he's showing us how he turned a USB hub into a RAID system using Flash Drives. Honestly, considering what we said about Flash drives in a previous post, I wouldn't be using this to store any sensitive data, but it does explain how RAID does work.

Anyway, the thing with RAID is that it is not a system used to backup your files. Okay, some configurations do duplicate your data, but that has more to do with data recovery in the case of failure than any form of backup protection. Honestly, you really should be looking at alternate ways to back up your data, and keeping the backup off site is also quite important. The other thing with RAID is that it increases hard drive performance, which means that two 1TB hard drives in a RAID configuration are going to perform better than a single 2TB hard drive.

Now, when data is saved to the drive, it is distributed across the drives evenly, but there are a few configurations for this as well. Since it is being distributed in this way, it means that if you have two drives in the configuration, and one of the drives fails, then, well, bye bye data. This is why RAID configurations generally use multiple drives, and when I say multiple, I generally mean more than three or four. Well, if you are configuring it in a RAID 0 configuration, it doesn't matter how many drives you have, if you lose one, it's bye bye data.

Anyway, RAID 0, otherwise known as 'Striping', means that the data is spread evenly across the drives in stripes. This does not help in the case of hard drive failure, but it does increase the performance of the drive. It is also quite easy to implement, but due to the chance of failure, it shouldn't be used for mission-critical data. The diagram below should give you an idea of how this works:

RAID 1 is called 'mirroring' and basically everything on one drive is mirrored on the next drive. The performance isn't any better than simply having one drive, but if one of the drives fails then you basically have a backup of the data on the second drive, and by replacing the failed drive, you can rescue the data. This can actually be combined with raid 0, as such:

This configuration is known as RAID 1+0 or 0+1.

Now, RAID 5 is much more complicated, but it actually provides the best of both worlds. Basically it strips like RAID 1, but it also has parity block interspaced to assist with redundancy. Basically, if one of the drives fails, then the data from the failed drive can then be restored using the parity data. However, for this to work you need at least three drives, though you can go for anywhere up to 16. The other problem is that it does tend to be expensive, and complicated.

We also have RAID 6, which is also referred to as 'Double Parity'. Basically the difference is that the number of parity sectors on the drive are doubled, so instead of there being one parity disc, there are two. This does mean that reconstruction time in the case of a failure is increased. However, if a second drive fails while one is being re-constructed, then the data has been lost. This is why RAID is no substitute for a secure backup.

Now, let's work out how long it will take to reconstruct a disk. So, we have 20 drives, consumer grade, holding 500 GB each, in a mirroring configuration, and write time is 90 MB/s, how long will it take to rebuild the failed drive?

Well, each of the drives has 500 GB, which makes it 500 000 MB, and at 90 MB/s we get 5556 seconds, or 92 minutes, or an hour and a half. If a second one dies, well, since it is in a mirroring configuration, as long as it is not the drive from which the data is being reconstructed, then you are pretty much in the clear. Oh, and since you have to read the contents of the drive, you will need to multiply that by two, which gives you about three hours.

Redundancy also works for power supplies, and you generally see this in computers that basically remain on, for, well, forever. This means that if we need to replace the power supply, turning it off is not an option, and in fact we really don't want the computer to shut down if the power supply fails. Okay, maybe if the computer is the server that houses Facebook, then it certainly won't be the end of the world, but if it is the servers that control the flight computers at Heathrow Airport then that is a different story.

Anyway, the way that works is that you have two power supplies that pretty much do the same thing, namely supply power. However, if one fails then the other can pretty much do the job all on its own. As such, you are then able to remove the one that has failed and then replace it with one that works. It's as simple as that.

Es ist kaputt - Equipment Failure by David Alfred Sarkies is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. This license only applies to the text and any image that is within the public domain. Any images or videos that are the subject of copyright are not covered by this license. Use of these images are for illustrative purposes only are are not intended to assert ownership. If you wish to use this work commercially please feel free to contact me

## Tuesday, 5 February 2019

### Nikola Tesla - The Tragedy of the Inventor

As I was wandering through the central business district of Perth we passed the town hall and discovered that there was an exhibition on Nikola Tesla. This immediately grabbed my interest, particularly since such exhibitions tend to be free (not that I'll wander into an exhibition based entirely on cost - there has to be some interest for me to spend some time wandering around the exhibition). I've always seen Tesla as somewhat of an enigma, particularly since he always played second fiddle to his contemporary, and boss, Thomas Edison. Yet, many of Tesla's inventions were at the cutting edge of technology at the time, and he did make quite a sum of money in his early years. However, as time went on, and his experiments become somewhat more extreme, he took on the title of 'mad scientist', and eventually died a pauper.

It is interesting that Elon Musk has named his company after Tesla, and one wonders whether he is destined to follow in the footsteps of his company's namesake. Like Tesla in the early days of electricity, Musk made his fortune in the early years of the internet and has since struck out on his own. Yet, he has funneled an incredible amount of money into developing the electric car, the patent which he has released into the public domain. He has also developed the power wall, a method to allow houses to store electricity for uses in down times. In fact, he seems to be focused on developing technology to effectively store electricity so that we become less reliant upon base load power that is produced by dirty methods such as coal fired power plants.

However, this post isn't about Elon Musk, even though there are some connections, but rather about Nikola Tesla, so let us instead look at his early life.

#### Life in the Empire

Telsa was a Serb, born in Smiljan, a village on the frontier of the Austro-Hungarian empire. While his father was a parish priest, he was also a bit of a technophile, making tools and mechanical appliances. At the time people in the region were being conscripted into the army, but Tesla managed to evade conscription, namely by disappearing into the woods where he lived a life as a hunter, and also spent time reading. Tesla studied at high school (called a Gymnasium in German) at Karvolac, where he managed to complete a four year course in three years. He was said to be able to do integral calculus in his head (which is an impressive feat, though it has been years since I have done integral calculus, so I can't really comment on whether it is possible or not, but I believe that it is). Mind you, the teachers weren't too impressed, and accused him of cheating (though how he did that is beyond me - it's not as if he could look the answers up on Google).

His university studies were conducted in the Austrian Polytechnic at Graz. Like Highschool, the lessons were conducted in German, which wasn't too much of a problem for Tesla. He had already shown a fascination with the power of electricity, though his aptitude did bring him into conflict with his professors. However, while he was successful at university (to an extent - he failed his final year and as such never actually completed his studies), he did get caught up in the lures of the University lifestyle (though I'm not entirely sure if life at the Austrian Polytechnic is anything like our modern universities). For instance he became a problem gambler - a temptation that I'm sure many a mathematical genius is lured into - though he was fortunate enough, after losing a lot of money, to eventually win it back, and break even. He basically left it at that.

 Tesla's boyhood home (or a reconstruction) By I, MayaSimFan, CC BY-SA 3.0

He moved to Prague with the intention of completing his studies, but not only did he arrive too late to begin the course, he also lacked a background in Ancient Greek (a required subject at the university), nor was he able to speak Czech (which, not surprisingly, was also a required skill at a university that happened to he in Czechia). He did 'audit' some courses, but never completed university, and ended up travelling to Budapest where he worked for the telephone exchange, and then eventually scored himself a job at the European branch of Edison's company in Paris.

#### The Current Problem

At the time the only form of electricity that was being used was direct current (otherwise abbreviated to DC). The problem with DC is that it can't be transmitted across long distances. This is the problem that Tesla wanted to solve, but his problem was that, like many young inventors, nobody took him seriously. The thing with breaking into the world of the big boys is that you need to either have some credentials behind you, or somebody who actually thinks that your ideas might be worth something. Unfortunately, Tesla had no credentials (he did flunk out of university), and his professors thought that he was a crackpot.

The difference between AC (alternating current), and DC is that alternating current periodically changes direction, where as direct current doesn't. As such alternating current can be sent greater distances. The thing with sending electricity over a distance is that it inevitably encounters resistance (known as the Ohm), which makes it weaker and weaker. As such if it is sent too far then it practically becomes useless. These days alternating current is what comes out of our power sockets, while direct current comes from batteries.

 Edison Factory in New York
The development of alternating current is what was to catapult Tesla into the history books, because it meant that we could then generate electricity at a central point, and then send it over distances to where it would be used. At this time you couldn't really transmit electricity, so if you wanted to use a lamp you needed to have some sort of battery to make your device work. However, Tesla went on to experiment with even more outlandish projects, including attempting to develop wireless technology, not only for communications (or the internet), but also as a means of delivering electricity. Mind you, the thought of having thousands of volts of electricity flying above my head is somewhat discomforting - I think I'll stick with the power poles (or as we called them in South Australia, Stobie Poles).

#### Moving to America

Edison's boss, Charles Batchelor, wanted to return to the United States, and in doing so brought Edison with him. He immediately began to work at Edison Machine works, but after six months left over a number of reasons. One of them was, not surprisingly, pay. Allegedly bonus were offered only to be reneged on later. Further, Edison was given the opportunity to develop a system of arc lights for street lamps, something that Edison's current designs were not able to perform. The problem with arc lights (which generate light by creating an arc of electricity between two points) is that they require an awful lot of energy to create. However, these plans were eventually shelved due to developments in other methods of lighting the streets (though these days streets are lit using a completely different method).

After leaving, Tesla continued to develop his arc lighting method, and gained the interest of a couple of businessmen. Due to Tesla's advanced designs, he gained some contracts to establish the system, but was soon to discover the harsh nature of doing business in the United States. While he had patented his designs, he had given them to his company in exchange for stock, and his investors eventually left to start their own utility. This left Tesla without a cent to his name, and found himself fixing gadgets and digging ditches, which to him felt like an insult considering his skills and knowledge (sort of like having a law degree and working in a call centre). As for his theories of alternating current, well, at the time, nobody was interested.

However his luck changed when he met Alfred Brown and Charles Peck, who agreed to fund his research into developing a viable AC motor. Alternating current was starting to gain traction in Europe, and due to the size of the United States, there was a viable use there. As such Telsa began to work on a motor that was superior to many of what were available at the time. He was then brought into the Westinghouse company as a consultant, since George Westinghouse was looking for a viable AC motor, and Tesla's seemed to do the job. As such he was given the kingly sum of \$2000.00 to work as a consultant. The problem is that Tesla was a man who did things his own way, and found himself in conflict with many of the engineers at Westinghouse.

#### The Induction Motor

Rumor has it that Tesla first came upon the idea while he was walking in a park in Budapest, and drew the initial plans in the sand. However, it wasn't until he met Brown and Peck that he was able to put time and energy into developing the motor. This motor was actually incredibly revolutionary, and is one of the cornerstones of our modern society. In fact anything that has a motor has a device that is based upon this invention of Tesla's.

The rotating magnetic field was first conceived by French astronomer Arago at the turn of the 19th century, and the theory was built upon by Michael Faraday. However, despite numerous experiments by Faraday and others, they simply were not able to put these theories into practice. In wasn't until Tesla came along that he was able to find a solution to the problems that were faced by Faraday and others, develop the motor, and eventually patent it. It was this motor that Tesla developed.

 By S.J. de Waard - Own work, CC BY-SA 3.0,

However, Tesla wasn't satisfied leaving it at that, and wanted to create a means of transmitting electricity wirelessly. This is where the famous 'Tesla Coil' came into play. After his success with the induction motor, we went to explore other areas of where he could put his skill into play. For instance he worked on a bladeless turbine. He then moved to Colorado springs, and being funded by none other than JP Morgan, he got his hands on a dilapidated laboratory and began to work on his theories of wireless transmission. However, at this stage it seemed as if Tesla had overstepped the mark, and despite making further discoveries in regards to the nature of Earth's magnetic field, Morgan decided to withdraw Tesla's funding - no doubt he could not see a sufficient return in his investment.

#### Wireless Energy

This was Tesla's pet project, and also the project that eventually bankrupted him. The idea of wireless transmission was something that was being explored at the time - Marconi was also experimenting with transmitting messages using radio waves as opposed to using cables. Tesla had already successfully experimented with a remote control boat, however he wanted to take it further - he wanted to remove the poles and wires from the transmission of electricity. His plan was to set up a series of transmitters and receivers, and the electricity would arc between the two. At the exhibition they had a much smaller device where the theory was demonstrated. The problem is that electricity is quite dangerous, and the voltages we are talking about could easily kill a person - so transmitting this wirelessly poses a huge problem. This is do doubt the main reason why nobody has taken up the idea since, and why we still rely on poles and wires.

 Tesla Coil - By Daniel Grohmann - Own work, CC BY-SA 3.0
Okay, the claim that mobile phones cause brain tumours seems to pop up every so often, but the fact that we have now been using mobile phones for something like twenty-five years (I got my first phone in around 1998), I don't see people dropping dead on the streets, or even a huge rise in the reported cases of brain tumors - and honestly, with the amount of mobile phones out there - there are apparently more phones than there are people in the world - you would expect that this would happen if the theory was true. Hey, pretty much every house has a wifi modem, and that it not including the free wifi you pretty much find everywhere. However, Tesla's ideas existed on a completely different level.

While Tesla was experimenting in Colorado springs with, Marconi successfully transmitted the first letter - S - from his laboratory in Newfoundland. Apparently Tesla picked this signal up in Colorado Springs, and believed that he had just received a message from off world - most likely Mars. The tabloids gobbled this up, though it eventually came to light that what he had heard was from Marconi. Marconi's success suddenly turned the attention away from Tesla. Tesla continued to attempt to generate interest in his projects, and would regularly visit the Waldorf Astoria in New York, but eventually mounting debts forced the banks to foreclose on his property in Colorado Springs, and the tower was demolished.

#### The Later Years

Tesla returned to New York where he stayed at numerous hotels, regularly moving about due to unpaid bills. He made a habit of walking to a nearby park everyday and would feed the pigeons. He would also spend time working on further inventions, but none of them ever matched the brilliance of his early years. In a way these inventions and ideas would become ever more outlandish. In 1931, on his 75th birthday, a party was thrown for this forgotten inventor of yesteryear, and he received numerous accolades from many well known scientists and engineers, including Einstein. However, Tesla was now well past his prime, and his glory days where behind him. He died on 7 January 1943 at the age of 86.

Of course, there is also the Tesla Coil, but I'll let Wikipedia deal with that one.

Nikola Tesla - The Tragedy of the Inventor by David Alfred Sarkies is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. This license only applies to the text and any image that is within the public domain. Any images or videos that are the subject of copyright are not covered by this license. Use of these images are for illustrative purposes only are are not intended to assert ownership. If you wish to use this work commercially please feel free to contact me