scholarly journals Excitation Properties of Photopigments and Their Possible Dependence on the Host Star

2021 ◽  
Vol 921 (2) ◽  
pp. L41
Author(s):  
Manasvi Lingam ◽  
Amedeo Balbi ◽  
Swadesh M. Mahajan
Keyword(s):  
Electromagnetic Radiation ◽  
Mechanical Model ◽  
Photon Flux ◽  
Quantum Mechanical ◽  
The Sun ◽  
Late Type ◽  
M Dwarfs ◽  
The Earth ◽  
Simple Quantum ◽  
Stellar Temperature

Abstract Photosynthesis is a plausible pathway for the sustenance of a substantial biosphere on an exoplanet. In fact, it is also anticipated to create distinctive biosignatures detectable by next-generation telescopes. In this work, we explore the excitation features of photopigments that harvest electromagnetic radiation by constructing a simple quantum-mechanical model. Our analysis suggests that the primary Earth-based photopigments for photosynthesis may not function efficiently at wavelengths >1.1 μm. In the context of (hypothetical) extrasolar photopigments, we calculate the potential number of conjugated π-electrons (N ⋆) in the relevant molecules, which can participate in the absorption of photons. By hypothesizing that the absorption maxima of photopigments are close to the peak spectral photon flux of the host star, we utilize the model to estimate N ⋆. As per our formalism, N ⋆ is modulated by the stellar temperature, and is conceivably higher (lower) for planets orbiting stars cooler (hotter) than the Sun; exoplanets around late-type M-dwarfs might require an N ⋆ twice that of the Earth. We conclude the analysis with a brief exposition of how our model could be empirically tested by future observations.

scholarly journals ON THE COSMOLOGICAL CONSTANT PROBLEM

1996 ◽  
Vol 05 (04) ◽  
pp. 433-440 ◽  
Author(s):  
DHURJATI PRASAD DATTA
Keyword(s):  
Cosmological Constant ◽  
Mechanical Model ◽  
Vacuum Energy ◽  
Quantum Mechanical ◽  
Cosmological Constant Problem ◽  
Molecular Physics ◽  
Simple Quantum ◽  
Time Formalism ◽  
Oppenheimer Approximation ◽  
The Universe

A simple quantum mechanical model of a closed interacting system is studied following the intrinsic time formalism developed recently, on the basis of the modified Born-Oppenheimer approximation. Apart from shedding further insights into the recent results on a possible nongravitating vacuum energy in the universe, the study also offers potentially interesting possibilities even in atomic/molecular physics.

Numbers and Shapes

2020 ◽  
pp. 36-53
Author(s):  
Demetris Nicolaides
Keyword(s):  
Mathematical Analysis ◽  
Scientific Method ◽  
Wave Functions ◽  
Quantum Mechanical ◽  
The Sun ◽  
Mechanical Wave ◽  
The Earth ◽  
Copernican Revolution ◽  
Modern Physics ◽  
Theory Of Forms

Pythagoras initiated the mathematical analysis of nature, a cornerstone practice in modern physics. “Things are numbers” is the most significant Pythagorean doctrine. It signifies that the phenomena of nature are describable by equations and numbers. Therefore, nature is quantifiable and potentially knowable through the scientific method. The Pythagoreans quantified pleasing sounds of music, right-angled triangles, even the motion of the heavenly bodies. The “Copernican revolution” (heliocentricity) is traced back to Pythagorean cosmology. But, finally, Einstein’s relativity clarifies a popular misconception related to it: that “the earth revolves around the sun (heliocentricity) is correct,” and that “the sun revolves around the earth (geocentricism) is incorrect.” Plato was inspired by Pythagorean mathematics, but he replaced “things are numbers” with things are shapes, forms, Forms, a noetic description of nature known as the theory of “Forms.” The quantum-mechanical wave-functions—mathematical forms that describe microscopic particles—are the Platonic Forms of quarks and leptons.

Low temperature dielectric relaxation in polyethylene and related hydrocarbon polymers

1970 ◽  
Vol 319 (1539) ◽  
pp. 565-581 ◽  
Keyword(s):  
Mechanical Model ◽  
High Density Polyethylene ◽  
Static Field ◽  
Quantum Mechanical ◽  
Loss Peak ◽  
Frequency Range ◽  
Maximum Loss ◽  
Simple Quantum ◽  
Hydrocarbon Polymers ◽  
Poly Ethylene

The dielectric loss tangent, tan 8, of a number of hydrocarbon polymers has been measured in the frequency range 10 Hz to 1 MHz between 1 and 4.2 K. Four different grades of poly-ethylene, together with poly(4-methyl pentene-1), shows a peak in tan 8, and this has been studied in some detail in Rigidex 3, a high-density polyethylene, where it has a form in-distinguishable from that predicted on the basis of a single relaxation time. The frequency of maximum loss decreases almost linearly with temperature from 4.3 kHz at 4.2 K to 950 Hz at 1 K, while the magnitude of the loss increases by a factor of less than 2 over the same temperature range. A large superposed static field reduces the magnitude of the loss, and enables an estimate to be made of the magnitude of the contributing dipole: P 0 = 0.58 ±0.06 x 10 -29 C m (1.75 ±0.15 D). This value, together with a typical value of tan 8 of 10 -5 , indicates that the dipole concentration is about 10 21 m -3 , although this can be increased by heating the polymer in air. In polypropylene and polystyrene tan 8 is independent of both frequency and temperature. A simple quantum mechanical model of the relaxation process is used to explain the experimental results: a particle in a double potential well tunnels from one well to the other with emission or absorption of a phonon. It is deduced that the particle is a proton, and the loss peak is ascribed tentatively to hydroxyl rotation in the crystalline regions of the polymer.

scholarly journals Effect of solar activity on electromagnetic fields and seismicity of the Earth

2021 ◽  
Vol 929 (1) ◽  
pp. 012019
Author(s):  
N.T. Tarasov
Keyword(s):  
Solar Activity ◽  
Ionizing Radiation ◽  
Total Energy ◽  
Electromagnetic Radiation ◽  
Electromagnetic Fields ◽  
Geomagnetic Storms ◽  
The Sun ◽  
Strong Earthquakes ◽  
Probability Of Occurrence ◽  
The Earth

Abstract It is shown that bursts of intensity of ionizing electromagnetic radiation from the Sun, as well as geomagnetic storms, cause a statistically significant decrease in the total number of earthquakes on Earth. After bursts of ionizing radiation from the Sun, a statistically significant decrease in the total energy of earthquakes occurs, and after geomagnetic storms, its increase is observed. This is mainly due to an increase in the number of the strongest earthquakes with MS > 7 after geomagnetic storms and a decrease in the number of such earthquakes after bursts of ionizing electromagnetic radiation from the Sun. During geomagnetic storms and for several days after them, the probability of occurrence of strong earthquakes increases more than two times, and after bursts of ionizing electromagnetic radiation from the Sun, this probability decreases almost twice.

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