How bitcoin works?

2013/06/24

Bitcoin is a virtual currency. In real currency, you have notes and coins which you can exchange for goods or services.

Bitcoin is a string of characters like 31uEbMgunupShBVTewXjtqbBv5MndwfXhb, (the real bitcoin is different, but lets assume it for the sake of argument).

There is an algorithm (not secret) which validates whether a bitcoin string is valid or not and whether it has been used previously (in other transactions or not). This transaction ledger is known as blockchain (analogous to a bank account or credit card statement).

You must have bought goods with your credit card. When placing order online, the merchandiser establishes a connection with the bank to validate your card is valid and has enough credit to spend.

In a similar fashion, for each bitcoin transaction, a bitcoin bank (some designated computer servers) validates the bitcoin string you are using and ensures it has not been used before.

So how bitcoins are generated? One needs a massive amount of processing power (thus multiple computers connected together) to generate a new bitcoin (i.e. to generate a string which is valid as per bitcoin algorithm). This process is called mining. The bitcoin algorithm suggests that only 21 million strings can be generated which will be a valid bitcoin. So far 50% of those have already been generated. The rest 50% is expected to be generated in next 5-10 years.

Just like you stash cash in your wallet, bitcoins are stored in a digital wallet. If not careful, your cash may be stolen and someone can use it on for their own purchase. In a similar fashion, if you don’t guard your digital wallet, someone can steal your bitcoins! Bitcoin wallets have addresses (like your Paypal address is your email etc.) like this one – 1JArS6jzE3AJ9sZ3aFij1BmTcpFGgN86hA. When transacting with bitcoin, one must send a bitcoins to receiver’s valid wallet address. However, to prevent someone stealing your coins, there is a safeguard concept called private key. You can say this is like a real key to your chest. If someone has the key, he/she can open your chest and get all your money (i.e. bitcoins) out.

The bitcoin addresses can be calculated from private key but not the other way round. So it is important that you do not lose your bitcoin private key!

Buying and selling bitcoin is similar to buying/selling any other currency. Its exchange rate also fluctuates like any real currency.

Why Microsoft created Windows 8 Metro interface?

2013/04/21

There was nothing wrong as such in Windows 7. However, unless businesses can make working things obsolete via upgrade to newer versions they won’t make enough money!

So Microsoft introduced Windows 8. However, unlike previous versions of Windows, they tried to force new Metro interface which is more suitable for touch screen devices. Most users were unhappy and wanted to revert to Windows 7 like interface. But why Microsoft introduced it in first place?

Metro and legacy Windows applications are not compatible. An app designed for Metro interface won’t run in traditional Windows environment. Metro apps can only be downloaded via Windows Marketplace. Now this is a very crucial difference. In earlier Windows, you could download apps from literally millions of websites. However, in Metro interface, your only option is Windows market place. This is similar to Apple’s AppStore concept. Microsoft did at because they wanted to capture 30% of all app sales. They can only do it if those apps are sold using their own app store only.

The trouble for Microsoft started when consumers did not like Windows 8. In fact various statistics show PC sales have been slowed down because consumers shunned Windows 8. Now Microsoft is caught between devil and deep sea. Backtracking from their Metro interface means potential loss of profit in future and acceptant strategic failure. However, if they continue to force Windows 8 Metro interface to consumers they may face continued backlash.

This is also the reason why Microsoft does not offer any option to start Windows 8 straight into legacy desktop! Because they want consumers to adopt their new Metro interface. Some consumers are using third oath apps to make Windows 8 behave like Windows 7.

But now you know why Microsoft did not offer these simple options themselves!

Why museums don’t allow flash photography?

2013/04/12

Not all museums prohibit flash photography. But some of them do. Some museums prohibit photography altogether but that is due to commercial reason.

So why flash photography is wrong?

There are several reasons behind this.

Some old artworks are made on perchments or some fragile materials which may fade quickly if exposed to strong lights. Thus frequent exposure to strong flash lights may accelerate the fading process.

Such artworks are often kept in dimly lit rooms. All the visitors eyes are accostommed in dim light. Now if suddenly flashes start going off then it becomes irritated to other visitors nearby. This is another reason i.e. to avoid disturbance to other visitors (it is similar to why you should not talk in loud voice inside museums).

Sometimes museum authories claim that flash interferes with their intruder detection sensor systems. However, not much detail is know if that is true.

How come bridge cameras can offer so much zoom?

2013/04/05

Nowadays many compact cameras can offer 25x-30x zoom. But having similar kind of zoom is not possible in DSLR cameras where it is mostly limited to around 11x-15x.

The reason why compact/bridge cameras can offer this (at a reasonable price) is these cameras have much smaller sensors compared to DSLR cameras. Thus, these cameras need much smaller lenses to cover that sensor. If you notice lens specification of these cameras they are usually at 4-100 mm range. While in DSLR, these are 18-200 mm range. Since DSLRs have much bigger sensors, they need massive lenses to offer long zoom range. This makes the lenses heavy and expensive.

So even though you can get away with very long zoom in smaller cameras, the image quality will be much inferior compared to DSLR’s APS-C or full frame sensors.

Image

Why DSLR cameras take better pictures?

2013/01/27

We know that usually DSLR cameras take much better pictures than compact cameras. But why?

This is due to 3 main factors. Firstly DSLR cameras have much bigger sensor. Typically these are APS-C or full frame size. Compact cameras have much smaller sensors which capture less details. Secondly, DSLR cameras usually have much better quality lenses. Thirdly, DSLR cameras offer lots of manual adjustments which allows photographers to have much better exposure and composition.

There are some bridge cameras which use APS-C size sensors. If these cameras use good quality lenses, then theoretically images taken by these cameras will be comparable to those taken by DSLRs.

Why most US locomotives have single cab while European ones have dual cabs?

2012/12/17

Most US locomotives have single cab. This creates a visibility problem when operating long hood forward mode (visibility is usually ok while operating short hood forward mode). However, it is quite rare for US locos to operate solo – they mostly work in pair (sometimes upto 3-4 units together as well). As a result, they rarely run as long hood forward mode in real life.

But in Europe, the overall weights of trains are lighter and thus often trains are pulled by just single locomotive. Here both forward/reverse operation is desired. Thus European locos need good visibility in both directions (otherwise they would need turntables which are now obsolete after steam loco era).

Countries which imported American locos (like common WDM style locos in India, licensed from ALCO) but often runs as single units, visibility is indeed a problem while running in long hood forward mode.

How cartograms are useful?

2012/11/07

A cartogram is a map where geographical entities are represented not by their land area but by some other parameter.

For example, following cartogram world population by countries where land areas are not actual areas but proportional representation of population of the country.

 

World Population cartogram

It helps to see immediately which countries are over populated against their land areas.

 

Why Euro NCAP ratings can be misleading?

2012/11/07

Euro NCAP test gives ratings to cars for safety of adult occupant, child occupant and pedestrians in case of any crash.

The maximum of 5-star indicates very high safety standard and least likelyhood of injury/death in case of a crash involving that car.

However, this ratings can sometimes be misleading if interpreted out of context.

People often assume that a small car with 5-star rating is as good as a large car with 5-star rating. No, it may not be the case!

The Euro NCAP frontal impact tests simulates crashing a car into another of similar mass and structure. This means that the ratings can only be meaningfully compared between cars of the same type and size.

The following structural categories are used in Euro NCAP test:

Passenger car
MPV
Off-roader
Roadster
Pickup

(In each category, cars which are within 150 kg of one another are considered comparable)

This means, occupants in a 5-star rated small car may suffer more injury, compared to occupants in a larger MPV of 3-star rating, if both cars crash head on.

What is Management Share Option Plan (MSOP)?

2012/11/04

When a company is doing very good, its board may decide to reward the management so that their good work (i.e. Increasing valuation of the business) is encouraged. This may be in the form of awarding more shares from existing shareholders to management team members. This at first may seem that detrimental to shareholders as it reduces shares allocated to them. However, this is usually done when management can increase valuation of company to a higher number by securing external investment or funding.

Although in mathematical terms the % ownership of each common individual shareholders reduces, the absolute amount of their investment increases. For example, this may mean share going down from 10% to 8%. However if original valuation of company was $100,000 and new valuation is $200,000 then corresponding shareholder’s wealth is actually increased from $10,000 to $16,000.

Of course management can reward them in alternate ways like paying them more dividend. However, MSOP is sometimes used as a tool to recover some ownership of business for other shareholders by major shareholders like management team. For young companies releasing cash via dividends is always good choice. So depending on company and situation and shareholders consent MSOP is exercised.

Why planes can’t land in fog?

2012/10/23

You may have seen that often flights are cancelled due to fog.

But we all know that modern airliners are equipped with sophisticated auto pilot system which can land aircrafts in zero visibility. So even then why flights are cancelled?

Even though auto pilot can land aircrafts in zero visibility, if this method is used, pilots can’t override it (if computer makes any mistake) if they can’t see the runway! At Minimum Decent Altitude, pilots need to see the runway so that they can decide whether to land or not. In case of zero/low visibility, there is no human backup.

Also, even if auto pilot lands the aircraft on runway, it pilots still need to taxi the airport to the terminals. Otherwise other aircrafts can’t land or takeoff. Auto pilot can’t do taxiing. In zero visibility, it is too risky to tow the aircraft to terminal building to align with aerobridges.