पकौड़ा

*चलौ पकौड़ा बेंचा जाय...*
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चलौ पकौड़ा बेंचा जाय,
चलौ पकौपकौड़ा बेंचा जाय ॥

पढै -लिखै कै कौन जरूरत,
रोजगार कै सुन्दर सूरत,
दुइ सौ रोज कमावा जाय,
दिन भर मौज मनावा जाय,
कुछौ नही अब सोंचा जाय,
चलौ पकौड़ा बेंचा जाय ।।

    लिखब -पढब कै एसी तैसी,
    छोलबै घास, चरऊबै भैंसी,
    फीस -फास कै संकट नाहीं,
    इस्कूलन कै झंझट नाहीं,
    कोऊ कहूँ न गेंछा जाय,
    चलौ पकौड़ा बेंचा जाय ।।

चाय बेंचि कै पीएम बनिहौ,
पक्का भवा न डीएम बनिहौ,
अनपढ़ रहिहौ मजे मा रहिहौ,
ठेलिया लइकै घर -घर घुमिहौ,
नीक उपाय है सोंचा जाय,
चलौ पकौड़ा बेंचा जाय ।।

      रोजगार कै नया तरीका,
      कतना सुंदर भव्य सलीका,
      का मतलब है डिगरी -डिगरा,
      फर्जिन है युह सारा रगरा,
      काहे मूड़ खपावा जाय,
      चलौ पकौड़ा बेंचा जाय ।।

मन कै बात सुना खुब भैवा,
उनकै बात गुना खुब भैवा,
आजै सच्ची राह देखाइन,
रोजगार कै अर्थ बताइन,
ठेला आऊ लगवा जाय,
चलौ पकौड़ा बेंचा जाय ।।

Olbers Paradox: Why is the sky dark at night?

At first glance, the answer seems to be obvious. After the sunset, the direct sun light does not reach the part of sky we see at night; so it is dark at night.

In fact, this question was first raised by a German astronomer Heinrich Olbers in 1826 who argued there are billions of luminous stars like the Sun in our galaxy, which apparently look faint as they are extremely far away from us but they do contribute to the background light in the sky.

Assuming stars have the same luminosity as the Sun, Olbers showed mathematically that the total contribution of light from the distant stars should be quite significant to keep the night sky bright even after sunset. Well, this argument may convince the astronomers but it goes against the observations since the sky is really dark at night. Then how to solve this paradox, known as Olbers Paradox.

The solution of the Olbers Paradox came from astronomical observations after one century. During the course of his extra-galactic observations (1926-1929) from the giant telescope at Mt. Wilson, American astronomer Edwin Hubble noticed a peculiar phenomenon. He found most of the nebulae (later turned out to be Galaxies beyond The Milky Way) were running away from us at tremendous speeds.

The farther the observed galaxy, the greater was the speed of its recession from us. He interpreted this phenomenon as a consequence of the 'expanding universe' by Hubble who is regarded as the Father of Modern Cosmology.

Prior to the discovery of the expanding universe, the astronomers visualised the universe around us like a huge star - studded globe with extra-galactic nebulae scattered all around our Milky Way Galaxy.
The stars and nebulae were known to have local random motions but there was no evidence of systematic expansions of the entire universe. Even Albert Einstein was carried away with the prevalent view of a static universe and missed the great opportunity of theoretical prediction of the expanding universe before Hubble observed it by telescope.

How does the expanding universe solve the Olbers Paradox? There is a well known physical effect, called 'Doppler Effect' governing the sound and light waves from moving sources, according to which waves from approaching sources carry more energy whereas the the waves from receding sources carry less energy. It is a common experience that an observer on railway platform finds the whistling sound of an incoming train of higher pitch than for an outgoing train. Similarly, in the expanding universe, the stars and galaxies receding away from the Earth, contribute in-significant energy to the background light and the night sky is dark.
Therefore, the night sky is dark essentially due to the expanding universe. It is also a glaring example as to how the cosmic events affect the local physics.