Of Bitcoins & Quantum Computing

April 6, 2018
There has been a lot of discussion in the media over the last few months on the rise of bitcoins and cryptocurrencies, and what it means for society and the economy. With uncertainty in the world due to Brexit and Trump and countless other political crises, individuals and organizations have been increasingly turning to the decentralized currency that is controlled by the masses, and as a result what was once given away for free a mere decade ago is now selling for tens of thousands of dollars apiece. Stores and businesses are starting to accept bitcoin payments, and a pub near where I grew up now has a bitcoin ATM in its lobby. Personally I knew that something big was happening when elderly relatives started asking me to explain to them what bitcoins are.

However there is a looming threat to the bitcoin boom, and even the best experts cannot say whether it will hit in a month or a year or a century. The threat is quantum computing.

The mathematics of cryptocurrency is a specialized field, and well beyond the scope of this article. However the basic concept is as follows. When you setup an account, there is a seed that is put into the software. Usually this is a pseudo-random number generated by the computer itself, but it is also common to have the user enter a passphrase, or even more secure is to have the user scribble some random lines with a mouse and convert the input to a number to generate a truly random seed for the account. 

This seed number is then fed into a complex algorithm that uses elliptic curves or similar methods to convert it into a much larger number called the private key. This number is designed to be so large that even the best supercomputers working on it fulltime will never be able to test every possible key. Once the user has this private key, they must keep it secured and never allow anyone else to access it - the private key is the only way that anyone can access the account and remove money from it. If it gets lost, the money is effectively destroyed and can never be used again.

Once the private key is obtained, the software can use it to generate a set of public keys. The algorithm that does this is a form of one-way encryption, in that the public key can only be generated by that specific private key, and yet there is no way of reversing the process to calculate the private key from knowledge of the public keys. In this way the public keys can be shared publicly, and yet the account is still secure.

Bitcoin transactions are then straightforward from the users perspective. Money is sent through the internet to a specific public key, and while anyone can view the money connected to that key, it is impossible to connect it to any account. The owner of the account however can claim that money, and use their private key to confirm that they are the owner of the public key as well. By using their private key to confirm their ownership of that money, they can then send it to other public keys and transact financial dealings without the need for an intermediary such as a bank or a credit card company to broker the transaction.

However there is a potential problem with this method of securing financial transaction, and given the sudden, rapid growth of cryptocurrencies it is a potential nightmare for the global economy.

The strength of the cryptocurrency is in the size of the numbers used for private keys. It is mathematically impossible to calculate the private key for a specific public key, and so the only way to steal bitcoins is to guess what the private key might be. With a traditional computer, or even a bank of supercomputers, this means trying one private key at a time and seeing if any of them unlock the account. But the number of possible private keys makes this a nearly impossible task. A warehouse full of supercomputers working fulltime for decades or centuries would still only be able to test a tiny fraction of all the possible private keys, and therefore would make stealing bitcoins virtually impossible.

There is however a new technology that is being developed currently, known as the quantum computer. As I have written before in previous articles, a quantum computer uses the laws of quantum mechanics to speed up calculations. One way to think of what a quantum processor does is to imagine the computer splitting itself into thousands or even millions of exact copies of itself, and each virtual copy does one of the calculations. When one of the copies gets the required result, all of the virtual copies disappear leaving only the one that got the necessary result.

In the case of bitcoins, each of the copies could test a single private key. Instead of testing a single key at a time such as a traditional computer does, a quantum computer could test millions at a time. And when one of those virtual copies finds a private key that unlocks a bitcoin account, it returns that key to the user who can then use it to steal the cryptocurrency stored in the corresponding account. Instead of a network of supercomputers taking centuries to unlock an account, a futuristic desktop quantum computer could unlock it in just a few hours.

Of course that is still just a theoretical threat to cryptocurrencies. There are private companies that claim to have manufactured working quantum computers, but in the academic literature the best quantum computers are still only able to factor two digit numbers and are not even as powerful as the cellphone in the researchers pocket. If quantum computers are to be a genuine threat to the security of the bitcoin system, they will have to improve quite dramatically!

But then again, there are people alive today who worked on classical computers that could barely do simple arithmetic, and who are now using complex machines that can simulate the entire Universe. And so it is not unbelievable that within the next few decades the growing quantum computing revolution could entirely cripple the cryptocurrency industry.

Perhaps decentralized currency is not quite as secure as we first thought...

The Future of Social Media

March 25, 2018
Today's article will be a departure from my usual scientific fare, and is a copy of an article that I recently wrote for a futurist website that I also contribute to. This is more of an editorial than a scientific review, and some users may wish to skip over it.

This has been a bad week for Facebook. By now I suspect most people are aware of the latest scandal, in which the user data of tens of millions of users was harvested by a British company that then used the information to influence vot...
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Hawking Radiation

March 14, 2018
With the recent passing of legendary theoretical physicist Stephen Hawking, I have received a number of requests to explain some of his pioneering research work in a popular format. To be honest it is simply not possible to do better than Hawking's own work in communicating his research to the masses. I would strongly encourage those who are interested to read some of his many popular science books to get a true understanding of his genius.

However for those who are still reading, I will make ...
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Stephen Hawking

March 14, 2018
There is sad news this morning with the announcement that the legendary theoretical physicist and science popularized, Stephen Hawking, has passed away at the age of 76.

He was a rare figure in the scientific community in that he made significant contributions to research, and yet he was also a famous celebrity outside of the theoretical physics community due to his popular books and willingness to bring modern physics theories to the masses. 

As an academic, he was noted for being one of the f...
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A New Test Of General Relativity

February 24, 2018
One of the great unsolved problems in modern physics is the nature of gravity. Since Einstein first published the general theory of relativity over a century ago, it has proven to be a very accurate model of the solar system and the cosmos. Repeated experiments have confirmed its predictions in the form of planetary orbits, gravitational lensing, and high precision measurements of time and frequency on the Earth and in orbit. So far no deviations from the predictions of general relativity hav...
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Surreal Numbers

February 23, 2018
I am always amazed at how simple some of the most interesting ideas and research in modern mathematics truly is. There are problems in mathematics that can be explained to a small child and yet the greatest minds of the past centuries have been unable to solve. Mathematics is one of the few fields of study where anyone can understand topics that the leading experts are still trying to solve. One such topic is the surreal numbers.

Everyone remembers as a child learning the integers, or counting...
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Energy Localization

February 10, 2018
After the memorial I posted earlier in the week, I have had a few readers ask me for more details about energy localization in the general theory of relativity. There are a few variations on this theory, and so I will try to focus on generic properties and as usual I will try to minimize formal equations in order to make this article accessible to a general audience.

The general theory of relativity was first published in 1915, and quickly confirmed by astrophysics experiments over the followi...
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In Memorium

February 7, 2018
There is some sad news to report this month, with the passing in January of one of my friends and mentors, Dr. Fred Cooperstock. Not only was he an accomplished physicists making significant contributions to the study of the general theory of relativity, but he was also a much loved and respected instructor to generations of physics students at the University of Victoria.

As a theoretical physicist he was best known for the Cooperstock Energy Localization Hypothesis, which argued that gravitat...
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Happy New Year!!

January 1, 2018
May you all have a happy and healthy 2018, full of enjoyment and prosperity. And may we all still be together again when the year ends and 2019 begins.

Happy New Year!!
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2017 Year In Review

December 31, 2017
Here we are at the end of another amazing year - it seems like just yesterday we were celebrating the start of 2017 and now it has come to an end. And though it was not the greatest year for the world at large, it has been a very good year for the scientific community.

The year started off with some very preliminary results being announced. The theoretical physics community saw a few hints of evidence of a holographic Universe in experimental data - though that is still quite controversial - w...
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About Me

Dr. Chris Bird I am a theoretical physicist & mathematician, with training in electronics, programming, robotics, and a number of other related fields.


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