Could we exist on earth under a red giant star?

About five billion years from now, the sun’s usual source of nuclear energy will be depleted. It will begin to expand and cool significantly, becoming a ‘red giant’. Its outer layers will be thrown off into space. As the sun loses mass, its gravitational pull will weaken and the planets’ orbit will widen. We know that mercury and venus will not be able to outrun the expanding sun, and will be engulfed and incinerated.

Earth may just outrun the swelling red giant but its proximity, and the resulting rise in temperature, will probably destroy all life on Earth, and possibly the planet itself. However, there’s no reason that life could not survive on another planet (or moon) sufficiently far out from the sun, as long as it lies within the sun’s expanded ‘habitable zone’. Life could also survive on suitably hospitable planets around other Red Giants.

Why do people cheat?

Because they want to win the easy way. As competitive animals, we human beings constantly seek out opportunities to gain money, food and sex, or simply to look good. Doing all this the hard way requires expenditure of time,efforts and energy, so cheating can obviously be very tempting.

Evolutionary game theory has helped to explain how altruism can exist alongside cheating. Generally, cheats do well when they are rare, but less well when they are many and have fewer non-cheaters they can exploit. So groups tend towards an equilibrium, with few enough cheats that it’s not worth the cost of stopping them. Sadly, this basic biological principle means we are unlikely ever to be completely free of cheats.

COULD LIFE HAVE ORIGINATED DEEP INSIDE EARTH?

The idea that life could thrive deep below earth’s surface was once regarded as heretical. Lacking any obvious source of energy, such as sunlight, and subjected to intense heat and pressure, subterranean organism would seem to have little chance of survival. Yet since the 1980s, bacteria, fungi and worm-like creatures have been found lurking kilometres down in mine boreholes and deep sea sediments. These organisms have extraordinary source of energy. For example, some bacteria rely on the reactions between water and rocks to get there energy.

Dating techniques suggest bacteria have existed at depths of several kilometres for at least 30 million years. What isn’t clear is where they fit into the history of life on earth: were they washed down, or are they progenitors of life on the surface? Either way, their existence has boosted hopes for life on Mars. While none has been found on the surface, NASA’s curiosity rover recently detected methane coming from within the planet – which may be the result of subterranean organisms.

What happens to the energy of light as it crosses the universe

Light coming from ever more distant galaxies has an ever-longer wavelength, or a ‘red shift’. According to physics, that should mean the photons of light have lost energy on their journey. Yet this overlooks the weird physics that kicks in on cosmic scales. In particular, it ignores the fact that the Universe – and thus the very fabric of space and time – is expanding. This literally stretches the light, increasing its apparent wavelength while leaving its energy unchanged. This explanation is still rejected by some, who argue it’s the cosmic expansion that’s an illusion, while the energy of light really does decrease through collisions with particles in its path. This so-called ‘tired light’ idea is intuitively much more appealing, and can be put to the test. For example, it predicts that distant objects will appear much fuzzier, as the higher-energy photons striking them will be scattered more violently. Yet images of distant galaxies show they’re relatively sharp. On the other hand, the cosmic expansion theory predicts that distant supernova explosions should appear slower than nearby ones, while tired light theory predicts no such stretching of time. Observations of supernovae have confirmed a cosmic ‘slow-mo’ effect – proving tired light wrong again.

DOES  PHOTOSYNTHESIS  OCCURS WHEN  MOONLIGHT  SHINES  ON  A PLANT?

Photosynthesis uses the energy from sunlight to convert carbon dioxide (CO2) and water into glucose and oxygen. Some of this glucose is used to build plant cells and some is converted back into CO2 and water to provide energy for the plant’s metabolism. The light from a full Moon on a clear night is only about one sixthousandth the brightness of an overcast day, but photosynthesis reactions will still occur, just 6,000 times more slowly. This is too slow to be useful to the plant because it will actually gain less CO2 from photosynthesis than it loses from the respiration of its cells. As the Sun rises each day, photosynthesis becomes more and more effective until the plant absorbs just enough CO2 to keep up with the amount burned for energy. This is called the ‘compensation point’ and it occurs in the early morning and then again in the late evening as the light levels drop again. Outside of these times, photosynthesis isn’t useful to the plant and many plants close their leaves at night so it doesn’t disrupt the circadian rhythms that control flowering.

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WHY  DOES  LACTIC  ACID  BUILD  UP  IN  MUSCLE?

During aerobic exercise our muscle ‘burn’ glucose with oxygen to produce carbon dioxide, water and energy. But when we are exercising hard, the lungs can’t keep up with the muscles’ demand for oxygen. Rather than just giving up, our muscle switch to an anaerobic chemical chemical reaction that doesn’t need oxygen.

This is less efficient because it doesn’t produce as much as enegy per molecule of glucose burned, but it’s better than nothing. Unfortunately, instead of water and carbon dioxide, anaerobic respiration produces lactic acid as one of it’s waste products. If you exercise hard, this will be produced faster than your bloodstream can transport it away to your liver where it is processed and broken down.

As the level of acid builds up in your muscles, you feel a burning sensation that acts as a warning that your muscle are almost out of energy. Like other sorts of pain, the ‘purpose’ is to signal that your body needs to rest. So, next time you go for a run bear your overworked body a thought and maybe catch your breath.