Wednesday, April 21, 2010

Planetary Habitable Zones

"For the host stars with effective temperatures lower than 4,600 K, the ultraviolet habitable zones are closer than the habitable zones. For the host stars with effective temperatures higher than 7,137 K, the ultraviolet habitable zones are farther than the habitable zones. For a hot subdwarf as a host star, the distance of the ultraviolet habitable zone is about ten times more than that of the habitable zone, which is not suitable for the existence of life." ~ "Habitable zones and UV habitable zones around host stars" by Jianpo Guo, Fenghui Zhang, Xianfei Zhang,  and Zhanwen Han

The "habitable zone" is something that is crucial in the conversation about life on other planets. The habitable zone is the intersection of two cosmological regions that must both be favorable to life: one within a solar system (circumstellar habitable zone) and the other within the host galaxy (galactic habitable zone). The galactic habitable zone defines a region that is close enough to the galactic core to provide a sufficiently high level of heavy elements to form rocky planets (like Earth) and yet far enough away so that high-frequency radiation does not harm or destroy life. The circumstellar habitable zone is usually defined as the region around a star where liquid water can exist on a planet. Recent research, however, has added a new constraint to the circumstellar habitable zone. This new constraint is an ultraviolet (UV) habitable zone. This region is a band around a star where any planets in it will receive enough UV radiation energy to drive the chemical reactions related to life’s origins (assuming a naturalistic evolution model) and yet not too much, which would result in the destruction of DNA. DNA would never be able to survive on a planet that is too close to its host star because of too much radiation, and it would never be able to form on a planet that is too far from its host star because of not enough radiation.

The paper cited above shows that in the vast majority of stars the liquid water habitable zone and the UV habitable zone do not intersect. "Effective temperatures" that the paper refers to are the temperatures of black bodies that would emit the same total amount of electromagnetic radiation as the stars being studied. Basically around any stars with effective temperatures below 4,600 K the UV habitable zone is too close to the star for liquid water to exist (it would all evaporate), and around any stars with effective temperatures above 7,137 K the UV habitable zone is too far from the star for liquid water to exist (it would all freeze). Around such stars there is no possibility for life as we know it. In fact, requiring a planet to fall within both zones (the liquid water and the UV zone) eliminates 80% of all stars as possible candidates for life-supporting planets. This adds to the growing body of evidence that Earth is uniquely fined-tuned for life as we know it.

By His Grace,
Taylor

Tuesday, April 13, 2010

Measuring Time From DNA

"As we develop better molecular methods, people would like it if the molecular dates reconciled with the fossil record. Then everybody would be happy, but instead the gap is getting wider, and in the end, that might actually be interesting." ~ Michael Donoghue

Michael Donoghue endorsed a paper titled "An uncorrelated relaxed-clock analysis suggests an earlier origin for flowering plants" about the origins of angiosperms (flowering plants) that was recently published in the Proceedings of the National Academy of Sciences by a team of researchers from Yale University and The National Evolutionary Synthesis Center. In this paper the researchers talk a lot about a technique known as "molecular clock analysis." This technique is a way that evolutionary biologists attempt to understand the relationships between organisms and the time frames where the organisms (presuming an evolutionary model) diverged from each other on the evolutionary track. Evolutionary biologists will compare DNA sequences from organism that exist today, use that information to attempt to build evolutionary trees, and then use molecular clocks to determine when the organisms diverged from each other on the evolutionary tree.

Let me attempt to explain how molecular clocks work. DNA has genetic "letters," which are abbreviated A, G, C, and T. The linear sequence of these letters contains genetic information (much like a word in language contains information because of its definition). The letters build genetic "words," which harbor the genetic information of the DNA molecule. Mutations can alter the sequence of genetic "letters" (much like a misspelling in a word) and molecular clock analysis attempts to measure the rate of these "misspellings" from mutations. If you compare two different DNA sequences which come from organisms that (presuming an evolutionary model) have a common ancestor and you know the rate of change/mutation of the DNA then you can extrapolate the time frame in which the organisms diverged from each other.

The problem with molecular clock analysis is that you have to make assumptions about the rate of change/mutation of the genetic "letters" in the DNA. Evolutionary biologists will attempt to calibrate the rate of change in the clock by going to the fossil record, looking at when certain organisms appeared in the record (organisms that are assumed to be evolutionary relatives), and then correlating the lapses in time with the changes in DNA to create a rate. They then take this calibrated rate and apply it to the entire evolutionary tree they have built to attempt to determine when organisms may have diverged from each other. The problems with this are: 1) it is notoriously difficult to do and 2) the results achieved by the analysis most often do not agree with what is seen in the fossil record. These researchers (from the teams mentioned above) attempt to get around these problems by varying the rate of mutation over time. They "relaxed" the clock. They vary the rate (often times by a lot and with rates too rapid for an evolutionary model) in order to get molecular clock analysis to match up with the fossil record.

Often times molecular clocks are used as a very important tools in molecular biology and cited as evidence for evolution. I like Donoghue's quote above because he seems to recognize the inconsistency in using molecular clocks to validate evolution. The fact that the "gap is getting wider" is "interesting" because it then either invalidates naturalistic evolution or invalidates the molecular clock method itself. This study shows us how flawed this technique actually is. It shows that there is generally no agreement between molecular clocks and the fossil record and that in order to get agreement researchers are rigging their inputs (relaxing the clock) until they get something that agrees with the fossil record. I am sorry, but this is not the way to do science. You can say that the rates may change over time (as rates often do) but you cannot just assume whatever rate(s) you want in order to get the results you are looking for. You have to have criteria that justifies 1) differing rates over time and 2) the specific rates you are using. What justifies using these different rates? For a scientist to do this they must have objective reasons for doing it. Playing with the data until you get the results you were looking for is not a reason. This hurts the case for molecular clocks being support for evolution. If you play with the data until you get the results you want (for the naturalistic evolution model) you cannot then turn around and say it is evidence for the evolutionary paradigm and this study highlights that particular problem. This paper shows that either molecular clock analysis (as it stands right now) is very flawed, the naturalistic evolution models are flawed, or both.

By His Grace,
Taylor

Sunday, April 11, 2010

Church II

I have come with one purpose
To capture for myself a bride 
By my life she is lovely 
By my death she’s justified 

I have always been her husband 
Though many lovers she has known 
So with water I will wash her 
And by my word alone 

So when you hear the sound of the water 
You will know you’re not alone 

Chorus:
‘Cause I haven’t come for only you
But for my people to pursue
You cannot care for me with no regard for her
If you love me you will love the Church

I have long pursued her 
As a harlot and a whore 
But she will feast upon me 
She will drink and thirst no more 

So when you taste my flesh and my blood 
You will know you’re not alone 

Chorus:
There is none that can replace her 
Though there are many who will try 
And though some may be her bridesmaids 
They can never be my bride

This song is by Derek Webb. He is a member of Caedmon's Call and also does side projects on his own. Caedmon's Call is one of my favorite bands and his solo stuff is also very good. I love the lyrics to his songs (and Caedmon's Call's songs) because they are so rich and have so many poetic allusions to biblical stories and/or doctrine. This one in particular I really like because of the bridge lyrics:


   So when you hear the sound of the water 
   You will know you’re not alone 
   ...
   So when you taste my flesh and my blood 
   You will know you’re not alone 



Seeing baptism and taking the Eucharist, among many other spiritual signs and symbols they represent, reminds me of the greater covenant community that Christians are a part of. The Eucharist is a covenant meal, which is an act of covenantal ratification much like the meal shared by the elders of Israel before God in Exodus 24. It proclaims Christ, seals the benefits of union to Christ in believers, spiritually nourishes the believer, and pledges the believer’s fidelity to Christ and His body. (I wrote a paper called "Covenant-Renewing Worship" that speaks some about this.) Baptism is a covenant sign that brings the children of believers, or new believers, into the covenant community so when you "hear" the water you know that you are not alone. 

Last week at church we had two baptisms: the baby of a member couple of the church and a believer's baptism of a young woman who had grown up Muslim (nominal Muslim, but Muslim none-the-less). Seeing both of those really encouraged me. When the baby was baptized I thought, "This is a lucky child because he will grow up in a covenant family that will love and support him." When the believer was baptized I thought, "She is now one of my own." I do not know her personally but she is now a professed Christian and part of the covenant community of the Church and just knowing that another has been brought into the Kingdom is encouraging. They were both encouraging because, like the song says, seeing them reminded me that I am not alone. Like John Wesley says, "Everyone who belongs to Jesus belongs to everyone who belongs to Jesus" (whether we like it or not). 

By His Grace,
Taylor

Friday, April 2, 2010

It's Friday, It is Only Friday...

It’s Friday
   Jesus is praying
   Peter’s a sleeping
   Judas is betraying
   But Sunday’s comin’

It’s Friday
   Pilate’s struggling
   The council is conspiring
   The crowd is vilifying
   They don’t even know
   That Sunday’s comin’

It’s Friday
   The disciples are running
   Like sheep without a shepherd
   Mary’s crying
   Peter is denying
   But they don’t know
   That Sunday’s a comin’

It’s Friday
   The Romans beat my Jesus
   They robe Him in scarlet
   They crown Him with thorns
   But they don’t know
   That Sunday’s comin’

It’s Friday
   See Jesus walking to Calvary
   His blood dripping
   His body stumbling
   And His spirit’s burdened
   But you see, it’s only Friday
   Sunday’s comin’

It’s Friday
   The world’s winning
   People are sinning
   And evil’s grinning

It’s Friday
   The soldiers nail my Savior’s hands
   To the cross
   They nail my Savior’s feet
   To the cross
   And then they raise Him up
   Next to criminals
   It’s Friday
   But let me tell you something
   Sunday’s comin’

It’s Friday
   The disciples are questioning
   What has happened to their King
   And the Pharisees are celebrating
   That their scheming
   Has been achieved
   But they don’t know
   It’s only Friday
   Sunday’s comin’

It’s Friday
   He’s hanging on the cross
   Feeling forsaken by His Father
   Left alone and dying
   Can nobody save Him?
   Ooooh
   It’s Friday
   But Sunday’s comin’

It’s Friday
   The earth trembles
   The sky grows dark
   My King yields His spirit

It’s Friday
   Hope is lost
   Death has won
   Sin has conquered
   and satan’s just a laughin’

It’s Friday
   Jesus is buried
   A soldier stands guard
   And a rock is rolled into place

But it’s Friday
   It is only Friday
   Sunday is a comin’!
~ S.M. Lockridge's famous sermon, from John L Jefferson, pastor of Del Aire Baptist Church, in Hawthrone CA.

I do not have anything deep to say to go along with this. I just wanted to post this short sermon because it gives me chills every time I hear it. I was reminded of it this morning when I started the Friday off badly by turning off my alarm in my sleep and oversleeping. I woke up, looked at the clock, jumped out of bed but then thought, "It is Friday and Sunday is coming."

By His Grace,
Taylor