Pioneer Anomaly: New Physics or Bad Maths?

1972 and 1973, NASA sent two unmanned spacecraft on a one-way trip to the edge of the solar system and beyond, Pioneer I and Pioneer II. These two spacecraft were sent to take pictures of the gas giants and give us insight into their structure, they did their job, scientists oohed and aahed at the results, updated all the relevant textbooks, and moved onto the next big project in science. But because scientists are inquisitive, and care about the well-being of the Pioneer craft, they kept tabs on them, to make sure they stay fit and healthy. This was meant to be just a routine check-up every now and then, just to see how far they go, but physicists discovered something strange. The distance between where Einsteins physics predicted the spacecrafts should be and where they actually were was different. Somehow, the crafts where slowing down. Now, they amount of deceleration was very small, less than one nanometer per second per second, but this was enough for scientists to really consider revising physics books, because nobody could think of anything that would cause this extra deceleration.

For scientists, this was a prime time to witness a paradigm shift, something key to the process of science. Some may think that science is just a steady progress of learning about nature, but its not. It actually involves rapid changes of ideas most of the time, in so-called paradigm shifts. This is a stage in science which occurs when evidence comes up which is contradictory to current science. After new evidence shows up, there will be further investigation from scientists to try to figure out what is the correct model, if the first evidence is overturned, and science stays with the current theory, this is not a paradigm shift. When the evidence is confirmed and new evidence supports it, scientists will formulate a new model which accounts for this evidence, and this is known as a paradigm shift.

Paradigm shifts are very important to science, as they mean deeper knowledge of the universe. But a possible paradigm shift which turns out not to be one is good too, because it means that our current model is pretty good. Pioneer was worthy of study to find out if the physics textbooks needed a re-write.

For almost 30 years, there hasn’t been enough evidence to formulate a hypothesis either way, and it has been an unsolved mystery to science, often called the Pioneer Anomaly. But now, a team at the Jet Propulsion Laboratory in California have an answer. The team published a paper in Physical Review Letters in which they demonstrated that some electronic components on the craft where producing small amounts of heat, and the force imparted on the craft from this heat was enough to cause the deceleration. “I think it is solved for good” said lead author of the report Slava Turyshev.

Great! The mystery is solved. Just put this down as another proof of Einstein’s Gravity. As a good scientist, you should know that any result is a good result. Confirming evidence just means one more piece in the puzzle which proves our theories, contradicting evidence means new physics, which is also good.

Could the laws of the universe be different?

Hello skeptics and other lurkers,

Today’s post again comes courtesy of a tweeter, who asked a question along the lines of this post’s title. This is a question which I have wanted to deal with for a while now, and I think that tonight is as good a time as ever for me to deal with it.

The laws of nature (as you should all know by now) are the laws which define the four fundamental forces we observe (gravity, strong nuclear, weak nuclear, electromagnetism) and the mathematical equations which describe these four forces. Most of the plight of modern particle physics is to find out as much as we can about these forces and equations, and see how it works out for the universe now, in the past and in the future, hoping to discover as much about our universe as possible, with the ultimate goal being to finish with one sum which describes all of these forces, the Theory of Everything (TOE). Last night I talked about string theory and the TOE, and this is one of the important parts in answering tonight’s question.

One of the most important ideas in particle physics is that, under extremely high energies, three of the fundamental forces (electromagnetism, strong nuclear, weak nuclear) can be united by one Grand Unified Theory (GUT) which describes all three forces. This theory has survived mathematical attempts at disproof and appears strong mathematically. This Grand Unified Theory is very important to particle physics. The hope is that, under EVEN higher temperatures and energies, this Grand Unified Theory can be combined with gravity to create the Theory of Everything. Gravity has always been a thorn in the side of physicists, and is actually the least understood and proven of all the fundamental forces, despite its obviousness in everyday life.

The hope and expectations are that gravity and the other three forces can be combined under higher temperatures to form one Theory of Everything. If it is true, as predicted by modern physics, then this has surprising implications for the four fundamental forces.

When the universe was born in the big bang, it was in a state of extreme heat, pressure and energy. Then it went under a process called ‘inflation’, where the universe expanded extremely rapidly (faster than the speed of light) and cooled extremely rapidly. There are two factors which are important in answering our question. 1. At the start, the universe was in a state of very high energy and heat, and 2. The universe expanded faster than the speed of light. Now, if there was ever a time in the history of the universe where the four fundamental forces would be combined, it would be right at the start.

Now, one hypothesis of a multiverse is extrapolated from this. If the universe went under rapid expansion while the four fundamental forces were combined, it could be true that, due to different parts of the universe being cut off from each other because of the speed of light, in different places, the universe could have cooled at different rates, meaning that the four fundamental forces could be different in those universes. Due to this hypothesis, it could be true that from one big bang, multiple universes could have been created. The definition of a universe is all of the things which can be observed, and seeing that these places are cut off from each other due to the speed of light, you have your self a multiverse, with different laws of physics.

This idea, like all multiverse hypotheses, has ramifications for the fine-tuning of the universe. It is one which is also hypothesized by accepted physics models, and is one if the easiest to accept, seeing that we know there must be much more out there than the observable universe.

Titius – Bode Law

Hi there skeptics,

Today I am going to be blogging about a mathematical formula which has had some interest in astronomy in the past, but has since fallen into the waste-bin of science. It has commonly titled as a law, in almost every reference to it and on the Wikipedia page, however, it is best described as an unproven hypothesis, as it has no evidence to support it. The law attempts to represent the approximate distances of the planets from the sun, using the following formula. a = 4 + n, where n = 0, 3, 6, 12, 24, 48, 96 etc., with each new value for n being double the last value. This gives rise to the numbers 4, 7, 10, 16, 28, 52, 100… divide this by 10, 0.4, 0.7, 1, 1.6, 2.8, 5.2, 10… To the 18th century astronomer, this is an astounding set of numbers.

The law was first formulated in 1766 by Johann Titius, who used this simple formula to get these similar numbers. This looked amazing at first, because these numbers fit almost perfectly with the distances in AU (astronomical units) of all the known planets, Mercury through to Saturn. However, there was one number in the sequence that shouldn’t be there, 2.8, no planet was known 2.8 AU from the sun. But sure enough, almost exactly 2.8 AU from the sun, the dwarf planet Ceres was discovered. This was very exiting for astronomers of the time. Could there be a deep, underlying formula to the planets.

They decided to look further, so they started with the next number in sequence, 19.6, and looked from there, and again, triumph, Uranus was discovered by William Herschel in 1781, and you guessed it, it was 19.2 AU from the sun, a mere 2% off the prediction. At this point, astronomers became drunk with enthusiasm, this number sequence is really working well. They went the next step, 38.8, but no, nothing was found. Neptune eventually became the next planet in order, but at 30.1 AU from the sun, it was 29% off, and the law was waning. Next, Pluto, predicted by Titius – Bode to be 77.2 AU away, alack, incorrect, only 39.5 AU from the sun, a 95% inaccuracy.

By this time, the law had fallen into disrepute. No more Titius – Bode being taken seriously by astronomers. Proponents of the law say that these ratios are being found as correct in other star systems around other stars, but these are stars with 1 or 2 planets, meaning that a ratio can always be found, or fit close, due to the set up of the number system. The idea of there being such a simple number which underlies all of the orbits is not one of favour in the astronomical community.

Who knows, there could be a number formula which describes the orbits of planets around a star. There must be, because they all follow the same laws of gravity. But the idea that there is a simple number sequence, not a large, abstract equation with hundreds of influencing factors, is a fringe opinion. Planets could naturally snap into particular grooves around their sun, but no number sequence has stood up to the challenge yet, so science tells us that it probably won’t exist.