Science, Art, Litt, Science based Art & Science Communication
Interactive Science series
Q: How do Oceans form? When meteorites or asteroids or comets strike Earth and form big craters?
MR: No. When such big heavenly bodies that can be as big as oceans strike Earth, everything here will get destroyed! Or perhaps a new moon will be born!
An object the size of a large house could easily wipe out a good-sized city. And the impact of an asteroid or a comet a little more than half a mile across would release about 1 million megatons of energy (several million times more than the energy released by the atomic bomb dropped on Hiroshima, Japan, in 1945). This would be enough to create a global catastrophe that would kill hundreds of millions of people and animals.
Our moon formed about 4.5 billion years ago, between twenty million and a hundred million years after Earth took shape. How exactly it got there is a matter of debate. Did it accrete in tandem with Earth, from the same proto-planetary stuff, or did it spin off afterward? Is it our fraternal twin or an identical one? Or was it adopted, drawn into our gravitational sway as it passed by? Since the nineteen-eighties, the consensus has centered on the single-impact hypothesis, sometimes known as the Big Splash or the Big Splat, which supposes that the moon formed when a planet-size object, often called Theia, crashed into Earth and sent a huge mass of debris into orbit.
About 30 million to 50 million years after the solar system’s birth, according to one theory, a Mars-size body called Theia struck the young Earth at an oblique angle. Both bodies were disrupted before gravity caused them to reassemble into a single planet (Earth) with debris orbiting around it. The debris blasted into space by the impact of Theia reassembled into two bodies orbiting Earth. The smaller moon was about 600 miles (1,000 kilometers) in diameter. Within about 100 million years after the birth of the solar system, Earth’s two moons crashed. The smaller moon became splattered across one hemisphere of the other moon.
In a paper in Nature Geoscience, a team of Israeli researchers proposed recently an equally compelling origin story: the moon, they submit, is the product not of one impact but of at least a dozen—and it isn’t just one moon but an amalgam of the many moons that came before it.
Now another theory about the origins of moon: https://blogs.scientificamerican.com/observations/a-new-theory-of-h...
Now coming to your main Q, Oceans are born at unstable seams in Earth’s crust, where plates pull apart, allowing molten rock to fill the gap and solidify. The fresh crust pushes older crust away from the seam and towards the edge of a continent. Eventually, the ocean crust crashes into continental crust and, through the process of plate tectonics, gets sucked down and recycled deep within the planet.
Because of this continuing cycle of creation and destruction, no seafloor is older than about 200 million years.
After the Ocean/sea floor was 'somewhat' established during early phases of Earth transformation into the present state, when Earth's surface had cooled to a temperature below the boiling point of water, rain began to fall—and continued to fall for centuries. As the water drained into the great hollows in the Earth's surface, the primeval ocean came into existence. The forces of gravity prevented the water from leaving the planet.
But only about half of the oceans got filled in this way. The rest of the water came from the icy comets that crashed into Earth.
Q: What is absolute zero? What exists at absolute zero?
MR: Absolute zero corresponds to the theoretical state in which particles have no energy at all. But physicists working with more exotic systems began to realise that this isn't always true! Absolute zero is the lowest possible temperature where nothing could be colder and no heat energy remains in a substance.
Absolute zero is the point at which the fundamental particles of nature have minimal vibrational motion, retaining only quantum mechanical, zero-point energy-induced particle motion.
By international agreement, absolute zero is defined as precisely; 0 K on the Kelvin scale, which is a thermodynamic (absolute) temperature scale; and –273.15 degrees Celsius on the Celsius scale.
Absolute zero is also precisely equivalent to; 0 degrees R on the Rankine scale (also a thermodynamic temperature scale); and –459.67 degrees F on the Fahrenheit scale.
But recent experiments using ultracold atoms have measured temperatures that are, in fact, negative in absolute temperature scale.
( http://science.sciencemag.org/content/339/6115/52 )
“Nothing exists at absolute zero.” According to the Laws of Thermodynamics, absolute zero is unobtainable. So nothing exists at that temperature.
The real reason nothing can exist at absolute zero is due the to 3rd Law of Thermodynamics, which states that “All systems in internal thermodynamic equilibrium at absolute zero must have the same entropy”. It was also known that as well as converging on the same point, the entropy/temperature curve of all systems would tend to have a zero gradient at absolute zero. Thus the proof is completed that it is impossible in a finite number of finite steps to bring any body to absolute zero.
But, again, recent research shows that ...
Quantum gas can go below absolute zero. Physicists have created an atomic gas with a sub-absolute-zero temperature for the first time.
( Braun, S. et al. Science 339, 52–55 (2013) ; http://www.nature.com/news/quantum-gas-goes-below-absolute-zero-1.1... )
However, some physicists say... Temperature is not defined in this way at all. They’re talking about how an expression for the internal energy of an ideal gas can be found in terms of its temperature. But in general the thermodynamic scale of temperature has nothing to do with an ideal gas.
Thermodynamic temperature, in classical thermodynamics, can be defined in terms of Boyle’s law, or in terms of the efficiency of Carnot engines running between heat reservoirs. In statistical thermodynamics it is simply related to the Boltzman factor B=1/(kT), and is defined in terms of the rate of energy transferred with respect to entropy.
It is certainly a state variable which can define a macroscopic state, and if that state is in thermodynamic equilibrium, then of course temperature is in some way a statistically interpretable quantity. Not all systems are in thermodynamic equilibrium. In a state of flux temperature is a locally defined quantity (though one that is very difficult to think about), and in continuum mechanics temperature can be given by a scalar field which obeys deterministic differential equations (that is to say, it evolves over time according to the diffusion equation or some equivalent).
Indeed, a single molecule can have a temperature. And a gas of photons can have a temperature. For example the cosmic microwave background radiation is a perfect planck distribution (black body radiation) and has a temperature of 2.7K.
So YES, temperature is a quantity associated with any substance. Not just a thermodynamic macro-state.
So, this is how science works! Trying to prove/disprove itself!
Nobody can have the last word here.
Q: In your article, ' be-alert-pseudo-science-and-anti-science-are-on-prowl ',
you wrote that science tries to disprove itself. But isn't it proof what makes scientific theories stick?
MR: Please read my previous reply. You will understand how science really works.
To be valid, a hypothesis must be falsifiable. Falsifiability is a defining characteristic of the scientific method. If a hypothesis can not be falsified, it is not a scientific hypothesis by definition.
When a scientist tests a hypothesis, he designs an experiment that could disprove the hypothesis. A good scientist does not look for evidence that a hypothesis is right, but rather that it is wrong. He makes a prediction based on the hypothesis, then seeks data about whether or not the real world conforms to that prediction.
This is probably one of the things most misunderstood by laypeople. Common people, conspiracy theorists, phony “medicine” peddlers, and other non-scientists look for evidence that their beliefs are true. That is, they seek to confirm their beliefs. This is not a good way to test whether an idea is true or not, because of confirmation bias, the mind’s tendency to see and remember things that confirm our beliefs and to ignore and forget things that do not.
A good scientist does not work that way and usually doesn't seek to “prove” a hypothesis. A scientist seeks to falsify a hypothesis. "Proof beyond doubt" means the theory had been tested
for both confirmation as well as falsification and the second one is the real proof!!!
But a hypothesis that was 'proved beyond doubt' stays that way only till somebody else finds a way to falsify it!
Still confusing?! :) Well that is the way the field tries to improve itself and is quite open to all possibilities.
Q: How do you trust something like science that changes continually?
MR: You should trust science because 'change continually' in the field means 'improve continually'.
Q: What is the science behind touch-me-not plant behaviour?
MR: Hmmm. Feel like playing once again with those wonderful leaves! Your Q brought back childhood memories.
There are certain plant species that undergo structural changes in a very short span of time; this is known as ‘rapid plant movement’. This happens when the receptors present in the plant’s body are activated by an alteration or modification of the plant’s shape. Mimosa pudica, better known as the ‘touch-me-not plant’, is one of the few plants that demonstrate this rapid plant movement. Although native to South and Central America, touch-me-nots are now found all over the world due to their amazing response to human touch.
Water within the cells and other cell contents apply a certain amount of force against the cell walls of the plant; this is called turgor pressure. It is due to turgor pressure that the leaves of this plant stay upright unless disturbed externally. Now, when you touch or shake the leaves (known as seismonastic movements), the swollen base of the leaf stalk (called the ‘pulvinus’), which contains certain contractile proteins, is activated.
When disturbed externally, certain regions of the plant trigger a release of various chemicals, including potassium ions, within the body of the plant. These chemicals make water and electrolytes flow/diffuse out of the cell, resulting in a loss of cell pressure. This causes the cell to collapse, which squeezes the leaves shut. Stimuli, in the form of touch, is sometimes transmitted to neighboring leaves as well.
Why did this plant develop such a mechanism? Researchers think that it may act as a defense mechanism of sorts for them like protecting from herbivorous insect looking for food and get confused by its folding leaves. It’s also thought that such rapid movements help the plant dislodge insects that may pose a danger to certain parts of the plant.
Q; Do frogs really freeze in very cold temperatures? How do they survive freezing?
MR: Wood frogs — native to northern regions of North America, from North Carolina up to Arctic Canada and Alaska — freeze almost completely solid during the coldest months of winter: As cold-blooded animals, their body temperatures can't resist changes in ambient temperatures. But the hoppers have evolved a mechanism to survive their frozen stupor, in which their liver breaks down a compound called glycogen into glucose (sugar), and releases that glucose into their bloodstream. The sugar behaves as a sort of anti-freeze in the animal's blood, keeping it alive as it hibernates through the coldest months of the year.
The frogs can live this way for weeks at a time, until temperatures rise back up above freezing. At this point, their hearts start to beat; they gulp for air, jiggle their legs, and hop away in search of a mate.
Q: How do animals communicate? They don't talk like us, although they make some sounds!
MR: There are three major ways how animals communicate with one another: Sound, Odour, Visual.
Q: In your article, the-most-difficult-part-of-science-communication
you wrote alternate medicines have to be tested scientifically to know their validity. Why don't we test them?
MR: Ayurveda is an old traditional branch of alternative medicine. It has several loopholes and flawed as it is untested scientifically in the modern sense. Ayurvedic medicines have been banned in several countries because of toxicity of the heavy metals used in them (they have tested them of course).
Why people don’t use scientific methods to test them? Because if tested scientifically we have to abandon several of these medicines and the practitioners of this system will lose jobs, colleges that teach this medicine will have to be closed. And these people will agitate. Moreover, the people here think we have to respect our traditions and shouldn’t desert them.
So we allow people to get cheated and bear side effects of these medicines. It is a short sighted approach.
(I will not say all the Ayurvedic medicines are bad, but some of them are. We have to test each one of them to assess their usefulness/potency/toxicity using modern scientific methods. Then only we will know how far we can really trust these alternative medicines.)
Q: In your article euthanasia-suicide-or-death-are-not-the-solutions-to-one-s-suffer you mentioned about HeLa cells and said they lost their ability to die. Can you give more information on them?
MR: On February 8, 1951 Dr. Howard W. Jones took a sample of cervix cells from a woman who had cervical cancer. Without her knowledge, researchers decided to keep those cells alive and cultivate them to investigate the nature of her tumor. The woman died in several months after that, on October 4. Her name was Henrietta Lacks.
Four years later those cells became the first successfully cloned human cells. What was unusual about them, they didn’t behave like any other human tissue. Dr. George Gey propagated the cell line and started using it in cancer research.
The abnormality discovered in that cell line was its inability to age. Most of the cells can divide only a limited number of times before they become senescent, but HeLa cells didn’t obey those laws. Given basic conditions required for cell’s survival, they were able to multiply at a staggering speed as long as those conditions were met. In other words, they were immortal.
Later HeLa cells were used for research on cancer, AIDS, the effects of radiation and toxic substances and gene mapping. Their extraordinary quick growth made it possible to produce enough material for experiments, which allowed, among others, to create polio vaccine quicker and make it ready for testing on patients. Tens of thousands of medical discoveries were made and millions of people were saved by this superpower demonstrated by a small sample of human tissue.
Dividing HeLa Cells; Picture credit: Getty Images
Q: What is cloud-seeding?
MR: The dropping of crystals into clouds to cause rain is called cloud-seeding.
Water freezes at 0 degree centigrade. That means below 0, it should turn into frozen Ice. Sometimes though, water goes into a super-cooled state. Which means, Water doesn’t get frozen even at, let’s say -30 degrees centigrade.
The important thing required for a rain to happen is having snowflakes in the clouds in the sky. So, if we need to convert this super-cooled water into snowflakes, we’ve to reduce its temperature further more.
Two things are used for that:
Q: I am a girl and I feel proud to see a woman running a science magazine. You are my role model. But I want to ask why aren't there many women in S and T field? How can we improve the situation? And who is your inspiration?
MR: Oh, thank you. Glad to hear that.
There are various reasons and I discussed a few in my article 'Being a woman is no obstacle in science'.
There should be a change in the attitude of each and every person in the society toward women. Parents have a crucial role to play too. What is more important is girls themselves should have the determination to succeed in the field. They have to lift themselves up to reach the top positions despite all the obstacles. You need great mental strength to do that. So...
all strong-willed people are my inspiration.