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Showing content with the highest reputation on 06/27/19 in all areas

  1. 3 points
    I appreciate you've though deeply about this issue - however this is incorrect. Regulatory genes can, for example, encode silencing mRNA which is used for post-transcriptional regulation of gene expression. RNA secondary structure can act to alter gene expression. Somatic V(D)J  recombination of existing genes is critical for adaptive immune function. There is an entire field of Developmental Genetics which deals with the mechanisms for differential expression during development - and the vast majority are genetically determined. Ultimately, the genome does a lot more than simply encode proteins, and much of its less obvious function is newly and incompletely understood - the term "junk DNA" was coined in 1972 to describe the 98% of the human genome that does not encode proteins. It wasn't until the 1990's that we started to unravel the function of non-coding DNA, but it does a lot more than we originally thought and were are still in the process of determining its function.
  2. 1 point
    Carl Sagan once argued about the improbability of aliens having visited Earth. He cited two main reasons: 1. the vast distances aliens would have to travel to get to Earth would be an almost insurmountable obstacle 2. the vast amount of time that separates civilizations during their rise and fall would make it unlikely that any intelligent civilizations would exist simultaneously On the other hand, Sagan has argued that he believes alien life is inevitable due to the vast numbers of planets and star systems that exist in the universe; he just doesn't think that intelligent beings have visited Earth, for the aforementioned reasons. I propose a counter argument. First, to agree with Sagan's general view of extraterrestrial life, the vast number of stars in our own galaxy alone makes it likely that some form of life does exist. These star systems undoubtedly contain billions of viable exoplanets. Even in our own solar system, planets such as Mars have been found to have water, and Europa, one of Jupiter's moons, is thought to have subterranean frozen seas. Is our own planet special? Probably not. Second, Sagan's point that civilizations would exist at different intervals, divorced from one another over eons of time, assumes one thing: that all intelligent civilizations would behave like Earth's. That is, all civilizations would rise and fall, as those on Earth do, and would eventually end in extinction within a relatively short time. But what if this isn't the case? What if other intelligent species establish equilibrium or harmony on their planet and can exist indefinitely, through the wise marshaling of resources and lack of egoistic competition? Why should we assume that all intelligent civilizations behave as haphazardly and ignorantly as human civilization does? Continuing this idea, if another species did reach evolutionary equilibrium, where it continued to progress technologically (and perhaps biologically also) but without inter-species conflict or discord, then that species could theoretically exist indefinitely - for hundreds of millions of years, (barring the lack of some existential catastrophe like a meteor strike). Further, if the species was continuing to develop technological as human do, then their capability for traversing the vast distances of space would exponentially increase also. With each passing milenia of stable progress an intelligent alien species would be more equipped to traverse the galaxy. It has taken human beings roughly 250,000 - 300,000 years to progress from a nomadic state to that of (limited) space explorers, but what would our technology look like if we steadily progressed without self inflicted anihilation for another 250,000 years? So the idea that an intelligent species could only exist for a short time is an assumption I don't think is 100% true. And IF that species is able to progressively develop their technology over eons without interruption, then who is to say that the vast distances of space would be any barrier? Additionally, how many star systems are there in our galaxy alone? Dr. Sten Odenwald, astronomer for NASA, writes in the Huffington Post that there are between 100 billion and 1 trillion stars in the Milky Way. At least 100 billions star systems, right in our own galactic neighborhood. Finally, there is the fact that the Earth is 4.5 billion year old, and has been inhabitable (with breathable air, water, and a viable food source) for 650 million years. Given these time frames, an alien species could definitely have evolved enough to venture out to explore its neighboring star systems and could have visited Earth already. So, while I agree with Sagan's view that alien life is more or less inevitable, I don't think that vast time or distance necessarily negate the possibility of aliens having visited Earth. Thoughts?
  3. 1 point
    Don't forget about all the galaxies we can't and never will see! also I've read that 90% of the galaxies we can see have already passed the point of no return and are not really there anymore (past the edge of the visible universe where it's faster than light) Maybe the above point would be a good motivator to leave your galaxy. Even travelling at slow speeds you would still have enough time to get here. I think alien life will more like the Heptpods in the film Arrival than green men
  4. 1 point
    There are issues with the idea of multiple temporal (time) dimensions. There are no* models or theories that rely on more than one temporal dimension and no experiment* have hinted >1 temporal dimension. There are are also papers** stating that >1 temporal dimension leads to unstable atoms. I think the idea of >1 temporal dimension affects physics on an even more fundamental level than required for a new explanation of the result of the dual slit experiment. In the context of the above you will have to provide some detailed instructions what to look for to confirm your idea. When running a dual slit experiment using regular equipment the scientist will confirm current models. What should the scientist look for, and what calculations are required, to show support for your idea? The logic is not clear. If I would be prepared to run an experiment I would need to know what to measure to confirm your predictions about additional time dimensions. There will be inference pattern when firing one particle at a time, and no hitting of a "front wall". See for instance single electron experiment at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4617474/ or http://l-esperimento-piu-bello-della-fisica.bo.imm.cnr.it/english/whatisabout.html. So how can that be a "key"? What have been overlooked? *) that is, no mainstream theory, model or experiment that I am aware of. I have not rigorously researched this. **) From https://space.mit.edu/home/tegmark/dimensions.pdf, dashed square added, highlights the OPs statement about 3+3 dimensions: Slightly OT: If you want to read a more philosophical article about the single electron experiment: http://l-esperimento-piu-bello-della-fisica.bo.imm.cnr.it/Resources/The scientific sublime - physicsworld.com.pdf
  5. 1 point
    https://phys.org/news/2019-06-santorini-volcano-terrestrial-analogue-mars.html The Greek island of Santorini is now one of the most popular tourist destinations in the Mediterranean, but 3,600 years ago it suffered one of the largest volcanic eruptions in recorded history. Among the material that was exposed, scientists have now found rocks similar to those of Mars. "In the Balos Cove, located to the south of the island, we have discovered basalts such as those that have been identified by the rovers on Mars and with properties similar to those of certain meteorites from the red planet and those of terrestrial rocks classified as Martian analogues," says Ioannis Baziotis, a researcher at the Agricultural University of Athens and co-author of the study, recently published in Icarus. more at link..... the paper: https://www.sciencedirect.com/science/article/abs/pii/S001910351830681X?via%3Dihub Santorini volcano as a potential Martian analogue: The Balos Cove Basalts: Αbstract The interpretation of geologic processes on Mars from sparse meteorite, remote sensing and rover data is influenced by knowledge gained from well-characterized terrestrial analogues. This calls for detailed study of candidate terrestrial analogues and comparison of their observable features to those encountered on the surface of Mars. We evaluated the mineralogical, geochemical, and physical properties of the Balos covebasalts (BCB) from the island of Santorini and compared them to Martian meteorites, Mars rover surface measurements, and other verified Martian analogues obtained from the International Space Analogue Rockstore (ISAR). Twenty rock samples were collected from the Balos cove area based on their freshness, integrity, and basaltic appearance in the field. Optical microscopy of BCB revealed a pilotaxitic to trachytic texture, with olivine and clinopyroxene phenocrysts in a fine groundmass of olivine, clinopyroxene, plagioclase, magnetite, and devitrified glass. All major minerals show normal zoning, including calcic plagioclase (An78–85 at the core and An60–76 at the rim), augite(En36-48Wo41-44Fs11–21), and olivine (Fo74–88). The dominant bands in the infrared-attenuated total reflectance (IR-ATR) spectra from BCB can be assigned to olivine (~875 cm−1), calcic plagioclase (~1130 cm−1), and augite (~970 cm−1). The whole-rock chemical compositions and mineralogy of the BCB are similar to published analyses of typical olivine-phyric shergottites and basalts and basaltic materials analyzed in Gusev and Gale craters on Mars. BCB porosity is in the range of 7–15% and is similar to the porosities of the ISAR samples. Although no terrestrial rock is ever a perfect match to Martian compositions, the differences in mineralogy and geochemistry between BCB and some classes of Martian samples are relatively subtle and the basalts of Santorini are as close a match as other accepted Mars basalt analogues. The Santorini site offers excellent field logistics that, together with the petrology of the outcrop, makes it a valuable locality for testing and calibration deployments, field training, and other activities related to current and future Mars exploration.
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