Gamma-ray detection:

Gamma ray sources are notable on Earth, mostly from thunderstorms, nuclear explosions, and radioactive decay.

However, detection of gamma rays from galaxies is very rare, and even if the Fermi Space Telescope does not detect any of them, this does not mean that galaxies do not emit gamma rays.

In support of the first detection of gamma rays from galaxies, I quote from NASA articles titled, "Gamma-ray Astronomy - Imagine the Universe!"

Gamma-ray detection is quoted below,

"The first detection of significant gamma-ray emission from our galaxy was made in 1967 by the the gamma-ray detector aboard the OSO-3 satellite. In fact, OSO-3 also detected the first gamma-rays from outside our galaxy! All told, it detected 621 cosmic gamma rays."

#detectionofgammaray #gammaray

#gammarayburst

Wavelength that electron microscope can see at best:

The entire electromagnetic wave force is carried by photons, and visible light is a small part of the electromagnetic spectrum, also at much lower frequencies, below gamma rays, X-rays, and ultraviolet radiation.

Visible light occupies only frequencies above infrared, microwave and radio waves - the lowest in the electromagnetic spectrum.

Therefore, electron microscopes, if at all, can only see wave frequencies higher than visible light, somewhere in the ultraviolet or, at best, the frequency range with wavelengths of about 10^-10 m.

Whereas, the wavelength of maximum frequency of gamma rays will be about 1.24 x 10^-20 m,

Therefore, the wavelength of gamma rays at the maximum possible frequency is about 10^-10 meters shorter than what most sensitive electron microscopes can see.

However, with no known gamma ray microscope, we see that gamma rays emitted in the early years of the Big Bang are converted to longer wavelengths upon reception, which are detected by Earth-based receivers/antennas or space telescopes. 

Gamma rays can be produced on Earth for experiments, moreover, gamma waves are produced by nuclear explosions, lightning, and less dramatic activity of radioactive decay on Earth.

#electronmicroscope #gamnaray #wavelength

About tiny vibrating strings:

It is thought that the Universe is made up of tiny vibrating strings, smaller than the smallest subatomic particles. Strings are one-dimensional extended entities in physics. In string theory strings are primitive objects and cannot be made of anything. Strings propagate through space and interact with each other.

Wikipedia notes, in physics, a string is a physical entity postulated in string theory and related topics.

Since, a string is a hypothesized physical entity, and so it is actually a suggestion or assumption of its existence as an argument, discussion and a basic principle from which further concepts are developed.

#string #strings 

Abstraction of space and dimension

Space is an infinite three-dimensional extent, where objects and events contain relative position and direction.

Dimension is an extension of the abstract concept of mathematics. For example, a line is one-dimensional, a plane is two-dimensional and space is three-dimensional.

Therefore, space is not an entity but an abstract concept.

Reference: Explanation

#space #dimension #extent #events #abstraction

Planck Length by Max Planck- quoted form Scholarly Community Encyclopedia

In 1899, Max Planck suggested that there existed some fundamental natural units for length, mass, time and energy. He derived these using dimensional analysis, using only the Newton gravitational constant, the speed of light and the Planck constant - it  was not yet called then.

Planck length, denoted ℓP, is a unit of length in the system of Planck units that was originally proposed by physicist Max Planck, equal to 1.616255(18)×10^−35 m. 

(Read more ... Planck velocity equals one Planck length per Planck time:)

The Planck length can be defined from three fundamental physical constants: the speed of light, the Planck constant, and the gravitational constant. 

The Planck length is expected to be the shortest measurable distance, since any attempt to investigate the possible existence of shorter distances, by performing higher-energy collisions, would inevitably result in black hole production.

The Planck length is approximately the size of a black hole where quantum and gravitational effects are at the same scale: where its Compton wavelength and Schwarzschild radius are approximately the same

The Planck length is about 10^−20 times the diameter of a proton

The Planck length is the length at which quantum zero oscillations of the gravitational field completely distort Euclidean geometry. The gravitational field performs zero-point oscillations, and the geometry associated with it also oscillates.

Reference: Planck Unit - from Scholarly Community Encyclopedia