Category Archives: Physics

What is an Equinox?

Today is the long-awaited spring, or vernal, equinox for folks in the northern hemisphere.  If you’re one of the 99.9% of people who are sick of winter then this is fantastic news.  In the Mid-Atlantic we’ve had one hell of a winter!  For three months it was just snowstorm after snowstorm and lots, I mean lots, of cloudy skies.  We also had the polar vortex swing by twice dropping temperatures into the single digits with sub-zero wind chills.  I think it’s fair to say that I am not alone in saying “Sayonara winter!”

The beginning of spring is officially today at 16:57 UTC or 12:57 EDT.  Why the exact time?  Well that’s because the changing of the seasons on Earth is indicated by the tilt of our planet.  As you might know the Earth orbits the Sun in a slightly elongated oval-shaped orbit.  Somewhat counter-intuitively it is not our position in our orbit that changes the seasons.  Did you know that Earth’s closest point to the sun actually occurs in early January?  Likewise Earth is furthest from the sun in the summer time.  It is actually how the Earth is angled with respect to the orbital plane that determines what season it is.  As the Earth orbits around the Sun it also spins causing day and night to come and go.  This rotation occurs around the Earth’s axis which is tilted about 23 degrees.  Throughout each year the Earth “wobbles” as it goes around the sun thanks to the inclination of the Earth’s axis.  When the Earth is tilted a certain way in respect to the Sun we call it an equinox.

The tilting of the Earth's axis throughout the year causing the seasons to change.

The tilting of the Earth’s axis throughout the year causing the seasons to change.

Equinox is a Latin term that means “equal night”.  During an equinox day and night are approximately the same length.  When an equinox occurs the plane of the Earth’s equator crosses the center of the Sun so that the Earth is neither tilted away or towards the Sun, causing an equal amount of sunlight to shine on both the southern and northern hemispheres.  As you can see from the incredible video below the day/night line (called a terminator) moves throughout the year if seen from space.  During an equinox the terminator is completely vertical.  In the case of the spring equinox the northern hemisphere has been angled away from the Sun for several months and thus has been receiving less direct sunlight and shorter days.  After the winter solstice during which the northern hemisphere experiences its shortest day the Earth begins to angle itself to point the northern hemisphere back towards the Sun resulting in longer days and more direct sunlight…summer!

This video is really hypnotizing.  What you’re seeing here is quite fantastic.  The video was taken using images from NASA’s Meteosat satellite.  Meteosat is a geosynchronous satellite which means it orbits around the Earth at the same speed as the Earth’s rotation so it always sees the same part of the planet.  As a result the planet never seems to move throughout the year.  In this video courtesy of Astronomy Picture of the Day and NASA, you see an entire Earth year in just twelve seconds!  You notice that the Earth’s terminator swings back and forth.  That is the seasons progressing as the Earth tilts on its axis.  The video begins on an autumnal equinox in September 2010 then the terminator swings over to the right giving the southern hemisphere lots of direct sunlight.  It reaches the solstice then swings back the other way towards the spring equinox when the terminator runs from north pole to south pole before swinging to the left and giving the northern hemisphere more light.  The video ends on the September equinox 2011 completing a full orbit around the Sun and an entire year for the people of Earth.

Because of our busy lives we tend to forget how dependent we are on the celestial mechanics of the solar system for life.  We owe our very existence to the fact that everything in the solar system, indeed the galaxy, moves in predictable orbits.  Thankfully for Earth our solar system is stable but that is not the case elsewhere in the galaxy.  In alien solar systems that we’ve only recently discovered there are planets that are drifting away from their stars and getting colder.  There are also planets that are being drawn inexorably towards their stars to eventually be consumed by them.  Other planets cross orbits too close to one another and are knocked off their orbits never to return to their home solar system.

We are lucky that our solar system has time to work out its kinks before life began on Earth.  If the solar system did not have orbital stability there’s a good chance life might not have arose here.  So be thankful we live on such a marvelous planet in a marvelous solar system!  On this spring equinox 2014 take a moment to think about the science that is behind the changing of the seasons and if the weather is clear tonight (fingers crossed!) go outside and take a look at the night sky and think that everything you see up there obeys the same laws that govern the seasons here on Earth.

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The God of Physics

The relationship between science and faith is one of a friendship gone sour.  The two used to be good friends who used to spur each other on to higher understanding. Early astronomers like Tycho Brahe and Johannes Kepler who were devout men of the Christian faith sought the mysteries of the cosmos to better understand the mind of God.  Even Sir Isaac Newton himself after publishing Principia Mathematica believed that the tightly-bound universe governed by mechanics and gravity was an insight into the mind of God and the brilliance of creation.   But over time science starting hanging out with other people and faith didn’t appreciate that much and got angry so they’re friendship became a bit testy.  In the mid 17th century science and faith signed what you could call a “non-aggression treaty” to agree to not intrude into the other’s territory.  For about 200 years science and faith were cordial at best as the Enlightenment gained momentum and the humanistic and materialistic culture of the 19th century took shape.  For many it was Charles Darwin’s work The Origin of Species that introduced evolution and natural selection that was the final nail in the coffin of the relationship between science and faith.

It used to be said that God was the God of the gaps.  Man used to wonder why it rained and so he said “God makes it rain” until we discovered that water vapor forms clouds that produce rain.  We used to ask why the sun rises and sets every day so we said “God moves it from east to west”.  Then we discovered that the planet rotates on its axis.  Eventually human curiosity and scientific observation filled almost all the gaps so there was essentially no more need for God in human thinking and God was confined to the minds of pious men of faith who were labelled “dim-witted” and “afraid of progress”.  By the end of the 19th century the thought of a divine being who had the ability to create and govern the universe was laughable to the vast majority of mainstream scientists and empirical evidence supposedly supported a universe that was un-ordered and chaotic and disproved the very idea of a creator.  Then there were physicists such as the great Albert Einstein who (based on his theory of general relativity) believed more or less that God was creation itself, that the universe was more ordered and desinged than we could ever imagine that a Creator must be behind it.  However,  the Creator of Einstein’s mind was the creation itself.  God was in the very stars, planets, nebulae, and black holes.  Very different from the personal, and anthropomorphic God of the Bible was this belief that is sometimes referred to as Pantheism.

There are a few people like myself (I am not a scientist by any stretch of the imagination!) who still hold to the belief that science and faith are not enemies, in fact they are more closely related than you could possibly imagine.  I can’t give a full discourse on why I believe this #1 because I am not as scientifically learned as required for such a proof and #2 because this is a blog, not a dissertation at Cambridge.  I am a man of faith, faith in the God of the Bible I might add.  I am equally fascinated in both science and faith.  My faith tells me that humans are created in the likeness and image of God and as such we are gifted with a mind capable of understanding the world we live in.  Not to exercise that gift, to stifle it, would in my mind be an insult to God.  For the sake of brevity (I may have already violated it) I will outline just one reason why I believe science and faith are friends still.  That reason is the theory of stellar and planetary formation known as accretion.

Accretion is the theory that stars and planets form from clouds of dust and gas that gravity causes to clump together to create a “runaway” effect of mass creation.  I will just focus on planetary accretion for now.  Once a star’s nuclear life has begun when hydrogen is fused into helium in the star’s core the outer elements are expelled and are thrown into an orbit around the new star.  The chaos of the elements causes them to constantly bombard other elements at massively high speeds and they begin to clump together.  The clumps get bigger and bigger as they begin to assert gravity of their own which attracts the smaller clumps and particle around them until a main bulge is created which is the skeleton of the new protoplanet.  Over many millions of years this process continues until all the dust and gas has been either accreted or expelled from the newborn solar system.  Accretion is not unlike a snowball being rolled down a snowy hill.  The snowball is small at the top of the hill but as it rolls down it gathers more and more snow making it larger and larger.  As it gets bigger and bigger the snowball has more surface area which allows it to gather more snow faster until it gets to the bottom as a huge and well-rounded snowball fit for a snowman.  This is the theory that explains how our planet and the others in our solar system were formed billions of years ago when the Sun was an infant.

Accretion of Earth Credit: Don Dixon/comsographica.com

If you’ve hung in there with me so far here’s where I make the connection with my faith.  In the Bible the book of Job is the story of a man named Job who is righteous before God and who has been blessed with prosperity and wealth.  Job has many possessions, a large family, and he is respected in the community as an elder and a wise man who is learned of the ways of God.  A conversation takes place between God and Satan where Satan is asking permission of God to test one of His people.  God suggests Job who is righteous in all his ways.  Satan claims that if he could just take away all his wealth and possessions Job will curse God.  God grants Satan permission to do so.  Job has every material blessing suddenly stripped away from him, he looses his flock and herd, his house is destroyed, all his children die, and Job is left with no claim to anything on the Earth.  What ensues is a very lengthy discourse between Job and three of his friends about why this horrible calamity has happened to Job.  They all suggest that Job must have sinned to bring such disaster and punishment upon himself, whereas Job questions God’s goodness because he knows his heart has always been upright before God.  Near the end God Himself enters the discussion and directly questions Job for his accusations against God’s goodness and power.  In chapters 38-39 God declares Himself as the One who caused creation to be and He declares His power over all the wonders of the Earth and the universe.  In Job 38:37 God says something very interesting regarding His creative technique.  It reads, Who can number the clouds by wisdom?  Or who can tilt the waterskins of the heavens, when the dust runs together into a mass and the clods stick fast together?”  This sounds remarkably like the process of accretion!  As far as we know, the ancient Hebrews had no knowledge of planetary formation so it is astonishing that God would say something like this to someone who would have no idea what He is talking about.  I believe it is clear that the “waterskins of the heavens” is a reference to the planets which the ancient people would have thought were just stars.  The dust that runs together into a mass sounds a lot like the accretion disk that forms around the newborn star which eventually becomes a planet or moon that “sticks fast together”.

To me this appears as clear evidence, not only that the Bible is more factual than most people could ever imagine, but that there are confirmations of our modern scientific knowledge in the Bible.  This proves both that our understanding of the universe has gotten us closer to the mind of God and that there is a divine Creator who operates the universe by a skillfully crafted set of rules.  The complexity and beauty of the universe is a testament to the unfathomable brilliance of God and His glory.  As Psalm 19:1 says, “The heavens declare the glory of God, and the sky above (the expanse in Hebrew) proclaims His handiwork”.  According to this knowledge my faith tells me that God created the universe and strictly governs it by a complex, yet beautiful set of laws that we are beginning to understand.  How marvelous is the prospect of being able get a glimpse into the mind of God by discovering the laws by which the universe operates!  Sadly, much of academia does not see it this way.  They assert the power of man’s mind and give no thought to a creator.  Let me close with another quote from Job.  Job 32:7-8 says “I said, ‘Let days speak, and many years teach wisdom.’  But it is the spirit in man, the breath of the Almighty , that makes him understand.” God grants wisdom to all men, but it is the Spirit of God that allows us to understand the true meaning of our wisdom…that it all points back to God.

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