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Space
Topics on the science of the outer space
Explaining the search for Einstein rings and Gravitational Lensing
Mar 14th
Gravitational lensing is the phenomenon by which the light that comes from a distant and bright object, because it is bent by a massive galaxy or a black hole, appears to be coming from multiple directions, from the point of view of an observer that has that massive galaxy between him and the bright object. You practically can see double images of the same object, or explained inversely, you can see the same object in several positions at the same time. Additionally, the phenomenon manifests itself through ringlike distortions of matter, also called Einstein’s rings sometimes, because the famous physicist predicted their existence by deriving their mathematical formulas from his general theory of relativity.
There are three types of gravitational lensing : (1) Strong gravitational lensing – where the spacetime distortions are very visible and manifest themselves through arcs, rings and multiple images of the same object, (2) Weak lensing – the distorsions are so small that they cannot be seen with the eye, so the must be verified statistically and (3) Microlensing – there is no distortion in the spacetime fabric but the amount of light that is received from the observed object varies over time.
In his theory of general relativity, Albert Einstein (1879—1955), explained the concept of gravity as the curvature of space-time around massive objects. What is space-time? Imagine it as a mental construct, a model that presents space and time as one whole system, for which all equations known in the theory of relativity and all the data obtained from scientific experiments fit 100% perfectly. So, imagine it as a mental tool that helps us bind the theoretical and experimental data perfectly. Bare in mind though, that this mental concept of space-time is a direct reflection of how time, matter and space are mysteriously interconnected. Einstein predicted that, because matter and energy bend space, that is, they curve the space-time fabric of the cosmos, matter can also affect the trajectories of the massless particles of light called photons. What’s interesting is that Einstein even predicted one of the most important consequence of gravity’s deflection of light, and that is the possibility of (geometric) gravitational lensing.
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Testing the curves with the LIGO (Laser Interferometer Gravitational Wave Observatory)
Mar 14th
Ripples in spacetime. This is what the joint effort of the California Institute of Technology and the Massachusetts Institute of Technology (MIT) are trying to gather experimental evidence for, with the Laser Interferometer Gravitational Wave Observatory (LIGO).
As we all know, curved spacetime is one of the direct observable effects of big chunks of matter and/or energy; this fact is theoretically explored by Einstein’s general theory of relativity, which states that matter and energy are alike, and one of the primary consequences they have on the world around them is that they bend or curve the spacetime fabric in their relative near vecinity.
A distinct category of this type of curved spacetime, which LIGO is trying to prove, is a kind of variable bending of space, one that is modified or propagated in a wave-like manner, like the ripples you would see when you would throw a pebble into a pond. Of course here we’re not talking about ripples in a pond, but big ripples in the fabric of spacetime. What is spacetime? Imagine it as a mental construct, a model that presents space and time as one whole system, for which all equations known in the theory of relativity and all the data obtained from scientific experiments fit 100% perfectly. So, imagine it as a mental tool that helps us bind the theoretical and experimental data perfectly. Bare in mind though, that this mental concept of spacetime is a direct reflection of how time, matter and space are mysteriously interconnected.
What are the ripples in spacetime caused by? By neutron stars orbiting each other, that is by the remnants of the gravitational collapse of massive stars during supernova explosions. Neutron stars are so heavy than when orbiting one another, they cause such powerful gravitational ripples in spacetime, that as far as from 70 millions of light years away, a installation like LIGO could easily detect them. Other causes might be colliding black holes, the explosion of a big star (supernova), and maybe a very special kind of phenomenon which was generated in the beginning of the universe which might validate some predictions of the Big-Bang theory.
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Explaining the search for EXOPLANETS
Mar 12th
430! That’s the number of exoplanets we discovered until the beginning of 2010. How did we do it? With the help of state-of-the-art spectrographs, interferometers, earth based or space telescopes, top-notch software and of course long hours of carefully examining the skies hopping to find planetary prospects for life’s development.
First of all. it’s important to state that the planets were not observed directly; we didn’t yet invent a telescope that could delve its way with enough clarity and magnification capabilities through the tens of light years of distance away, so that it could offer us a compelling and clear picture of an extrasolar planet. At least not yet.
All planets thus detected were observed by indirect means. By taking advantage of the prospective extra-solar planet’s effects on the star which it orbits, effects that manifest themselves by affecting the movement, brightness and characteristics of the light spectrum of that star, scientists have thus far discovered a myriad of exoplanets, even though the majority of them are massive gas giants like Jupiter, Saturn, Uranus and Neptune. The most known four general methods used to detect exoplanets are: (1) The Doppler Shift (or Radial Velocity) Method, (2) The Transit Observation Method, (3) The Astrometric Measurement Method and (4) The Gravitational Microlensing Method. Beside these we will talk about (5) The Direct Detection Method, (6) The Nulling Interferometry Method and (7) The Polarimetry Method. Let’s begin!
