There are many so called “science facts” we take for granted to be true,
but I can think of at least five so-called facts that are widely-believed but aren’t actually true.
In fact they are so ingrained in our psyche that you might not believe what I am saying, and will
probably be Googling them to double check. And I encourage you to do that, because I would too.
So what are these facts that I’m going to refute? 1) There is no gravity in space. Incorrect. 2)
Nothing can go faster than the speed of light. Physics has no such limit. 3) Bees shouldn’t be
able to fly according to physics. I will explain this using Physics 4) Humans evolved from chimps.
Absolutely wrong, and 5) The Big Bang explains the creation of the universe. It does not.
If you want to know why all these facts are wrong, stay tuned because that’s coming up right now…
The most visible force on cosmic scales is without a doubt gravity. It keeps
our feet firmly planted on earth and the earth in a stable orbit around the sun.
You’ve probably been told that there is no gravity in space. That’s not true. In
fact gravity is everywhere in space. It has infinite reach. This can be seen in Newton’s
law of universal gravitation. The “r” in the denominator is the distance between
objects. This number can be as large as you can imagine, gravity would still be present.
It would be weak at very large distances from massive objects, but never zero.
This means that the sun has a non-zero gravitational effect everywhere in the universe. And so does the earth. In fact, so do you!
Again, this is going to be extremely weak the further away you go, but it's never zero.
Newton's equation also shows that close to massive object like the earch
gravity is quite strong. In fact, you might be surprised to hear that the force of gravity
on the international space station, which is in 250miles or 400km away in space,
is almost the same as on the surface of the earth.
So why are the astronauts floating when you see them on TV? Well, you feel your weight if
you stand right now because gravity of the earth is pushing you to the ground,
and so your feet exert a counteracting force upward against your body so
you can stand up as the downward force of gravity pulls you down.
In space it’s different, the astronauts and the space station have mass so the earth’s gravity
still acts on them, but because of the orbital motion they follow in space, there is a force
component going away from earth which is equal and opposite to the force of earths gravity.
Gravity is still there being so close to earth, in fact it’s about 90% of what it is on the surface
of the earth, but because there is no external contact force pushing or pulling on their body,
they feel no weight. They are in fact in freefall. An orbiting astronaut and
space station is like an untethered falling elevator; you would feel weightless
inside for the same reason. The difference is that the satellite is falling so fast
to the side that it continuously misses the Earth’s surface, allowing it to fall forever.
This is what an orbit is.
Note that when I say that gravity has infinite reach, it does not mean that the gravity of our
sun, earth and us has reached out infinitely far away. The effects of gravity travel at the
speed of light, that is, the speed of photons, so essentially our gravity extends out to everything
that we can see. And everything that we can see also affects us gravitationally to some
negligible degree. But the universe is larger than the observable universe, and so we would
not feel any of the gravitational effects of any objects whose photons have not reached us yet,
since both photons and gravity travel at the same speed. If you want to learn more about
some of the theories regarding how far our universe might extend beyond the visible,
there is a great documentary available on MagellanTV, today’s sponsor called, “Search
for the edge of space” – it shows how what we can see probably only represents only a tiny fraction
of all there is, and what might lie beyond. It tries to answer the fascinating question,
“Where does it all end?” And you can check it out for free right now by clicking the link in the
description because Magellan is offering a free one month trial to Arvin Ash viewers. So you can
not only enjoy the documentary but also support us by signing up at the link in the description.
Another common misconception is that nothing can break the speed of light because physics
said so. The truth of the matter is that physics never put in such a limit.
You might say, but Einstein’s law of relativity says so! It doesn’t actually say that. In fact,
we are quite sure that the speed of light limit has been exceeded.
What physics tells us is the following. Any massless particle must move at the speed of
light. Anything with mass cannot be accelerated to the speed of light, because it takes an
infinite amount of energy to accelerate a massive particle to the speed of light. So you can only
get a massive object infinitesimally close to the speed of light, but never at the speed of light.
Most importantly, information cannot travel faster than the speed of light,
as this would break causality.
Now you might say, but wait,
now you are telling me you can’t break the speed of light. No, I’m not.
Spacetime can for example expand faster than the speed of light,
and we believe this happened in the very early universe during what’s called the cosmic
inflation epoch. This is when space expanded exponentially in the early universe. This helps
explain many mysteries of our universe, like the homogeneity of the cosmic microwave background,
the apparent flat geometry of space, and the origin of large scale structures which
are thought to have arisen as tiny quantum fluctuations got fixed into large scales.
But information never travelled faster than the speed of light.
Similarly, there is something called the group velocity of light that can travel faster than c.
You can think of this as a pulse of light composed of the sum of various frequencies of light. The
bump is the brightest part of the light containing most of its energy. If you were to see this light
it would appear to be dim, then brighten then dim again. Such a pulse travels at c in the
vacuum of space. It travels slower in some media like water or glass. But there are some special
materials in which certain frequencies of light exhibit something called anomalous dispersion.
Without getting into the details, what this means is that the bump becomes narrower and
bunches up in the middle. This bump, as shown in this illustration travels faster than the bump
on the light traveling at c. Since the bump represents most of the energy of the wave, it
seems to appear that light energy travels faster than c. So what’s going on? Well here’s is the
key. Although the bump travels faster than c, the leading edge of the pulse travels at the
same speed as the leading edge of pulse in empty space. What’s special about the leading edge? This
is where the information is contained. It carries the information that, "aha, light has arrived."
So even in this case, information does not travel faster than the speed of light in
a vacuum. This is the main principle of Einstein’s theory of Special Relativity.
Why can’t information travel faster? Because this would break causality. Something in the
future could affect the past, such that the future never occurs – the
grandfather paradox. If you want to know the details, I made a video about that up here.
Now, let’s move on the story of the biologist and the engineer.
The story goes something like this this. A biologist and an engineer go to a bar. After
a few drinks the engineer begins talking about math and the biologist about bees.
The result of the discussion is that the engineer concludes that
according laws of aerodynamics, the bumble bee is incapable of flight,
because it cannot produce enough lift to fly. This story is almost certainly
more legend than real, but nevertheless, legends are based on a kernel of truth.
The problem can at least be traced back to 1934 when the French zoologist and
aeronautical engineer, Antoine Magnan, came to the conclusion that Bees should not be able to fly.
How did he come to this conclusion? In short, by measuring the mass of the bee,
you can calculate how much force you would need to lift the bee. Then he looked at the wings and
computed the maximum lift they could create. He found that maximum upward lift force would be
less than the gravitational force downward. So he concluded that the bee should not be able to fly.
Since bees clearly can fly, this remained a mystery for over 70 years. But researchers
at Caltech and the University of Nevada finally figured it out in the early 2000s. The solution
is very interesting. There was a mistaken assumption in Magnan’s original calculations.
The assumption was that the wings of a bee work in a similar way as the wings of a bird.
In order to fly, birds flap their wings up and down. But the thrust or lift that
enables the birds to fly is only generated during the downstroke. No lift is generated
in the upward stroke of the wings. So roughly speaking, only half of the wing movement is generating lift in birds.
As it turns out, bumble bees don’t fly like this. They don’t actually fly like birds. They
fly like bees. And bees flap their wings back and forth, not up and down. And lift is generated in
both the forward and backward stroke. So the rapid rotation of the wing as it flops over and reverses
direction, combined with a very fast wing beat creates more than enough lift for bees to fly.
You can somewhat replicate the mechanism of bees flying yourself by treading upright in water,
in other words, by trying to stay afloat in one place. As you move your hand back and forth,
the changing angle of your palm creates a lift in both the forward and backward stroke of your arms,
keeping you from sinking. In fact, many of the movements in swimming use similar techniques.
And while we are on the subject of bees, did you know that bees directly affect human nutrition.
We rely on them to pollinate many if not most of our fruit and vegetable crops. Without them,
we would lose many of these foods. So maintaining the health of bee populations is very important
to human health. But the population of earth’s bees is declining. And this is largely due to
human encroachment on their habitats. There is a fascinating documentary on MagellanTV
that looks at some really clever ways to grow the bee population while also growing
our crops. I have a link to this documentary in the description. And you can check it out
for free by taking advantage of the free one month trial offer from MagellanTV.
Staying in the realm of biology, another common science fact that’s wrong is the
idea that humans evolved from chimpanzees. They did not.
Let’s try to get the facts straight on this one.
Modern chimps and humans are related. But neither evolved from the other.
You might say they are cousins because they share a common ancestor,
that lived between 6 and 8 million years ago. This common ancestor, over time,
diverged into two different species probably due to, among other factors, environmental
variation that suited different evolutionary paths in different geographic locations.
How do we know? Well, the strongest evidence is inside us, in our DNA.
Chimps and humans share 98.8% of their DNA. They are our closest living relatives on earth. We
share more of our DNA with chimps than not only any other animal, but also more than any other
great apes such as Gorillas and orangutangs. The closer in DNA a species is to another,
the later their common ancestor would have existed. It stands to reason then that humans
and chips likely diverged relatively recently on evolutionary time scales.
One thing I want to point out, that is not readily apparent from this chart is that there was not a
smooth line from the common ancestor leading directly to humans on one branch and chimps on
the other. The fossil record shows that there were many other branches in between on the 8
million or so year journey to modern humans. And the same is likely true for modern chimps. To give
you an idea, our species, called homo sapiens, is only about 300,000 years old, and we evolved from
another human species called Homo Heidelbergensis. In fact, we coexisted for thousands of years with
other species of humans including Neaderthals and Homo erectus among others. Today, we are the only
surviving human species on earth, but if you want to learn more about the fascinating journey of how
modern humans evolved and eventually took over, check out the documentary called “Sapiens: the
new origins” on MagellanTV. This documentary shows how reexamination of an old discovery in Morocco
completely changed our view of the geographical origin of humans. That link is in the description.
And again you can see it by taking advantage of the one month free offer from MagellanTV.
Some people may say well evolution is just a theory, so all this is just conjecture. Well,
in science a theory means something different than the way this word is
used in casual conversation. It does not mean a hunch, or conjecture. It means a broad,
evidence-based, natural explanation for a phenomenon. It is a theory in the sense
that in science everything is always under scrutiny and is constantly being updated
as our knowledge continues to increase through research and evidence-gathering.
Evolution is not controversial among scientists. It’s the cornerstone of modern biology. There is
no question whether evolution occurred or whether it played a central role in the history of life
on Earth. It is widely observable in laboratory and natural populations as they change over time.
A recent example of this can be seen in the city of the world’s largest nuclear accident,
the Chernobyl exclusion zone. Biologist have found over the few decades since the accident,
how a new frog has become much more prevalent there.
Originally, Eastern tree frogs of the area would generally be
bright green. But now it’s found that they are increasingly black.
It turns out that there is a good explanation. The dark color comes from the natural skin pigment
melanin. And one of the benefits of melanin is that it protects again ionizing radiation such
as UV rays, which is why humans have developed darker skin in some regions of earth that get
a lot of sun. But Melanin also seems to protect against nuclear radiation from the accident scene.
So the frogs who had more of this pigment when the accident happened were more likely
to survive and reproduce. And since their offspring are more likely to be dark,
today we see the area dominated by dark tree frogs. Dark frogs outperformed green
frogs in this toxic environment. This is an example of evolutionary
change occurring right in front of our eyes. So there's really no question that evolution happens.
Keeping on the theme of evolution, the best theory we have on the evolution of
the universe is the Big Bang theory. But one of the biggest facts people
get wrong about it is that the theory explains how the universe came to be.
The big bang theory says nothing about how the universe was created or where it came from. This
a big misconception. What the theory describes is how we got the universe we see today from a much
hotter and denser universe near the beginning. It describes everything that happened after the
beginning, not at the beginning nor before the beginning. In other words, it explains
everything that happened after the moment of creation, not how that creation took place.
The Big Bang theory gives us an explanation of how protons and neutrons formed and later
fused together to form the atoms that make up the universe. It tells how the
universe has grown from a small size, to the huge universe we see today. And we
can trace the steps that led to this. It’s a theory with a lot of evidence to support it,
and is the best theory we have that traces the evolution of the universe from near the beginning
to today. If you want more details on the the Big Bang, check out the video I did on that up here.
As far as how the universe was created or what events may have taken place which led
to the Big Bang, we have no idea. There might not be anything like a time before
the Big Bang because time is thought to have started at the Big Bang as well.
How do we know the Big Bang even happened? Well, the Big Bang model predicts an expanding universe,
and a near uniform ever present, black-body microwave radiation, and a primordial element
ratio of approximately 75% hydrogen and 25% helium. Well, these are precisely what we
observe in the universe. While each of these on its own would not prove the Big Bang model to be
unequivocally correct, taken together, it’s almost foolproof evidence that the Big bang actually happened.
So on that explosive ending, let me know what you think of this science
debunking videos like this. Would you like to see more in the future? Let
me know in the comments. I will see you in the next video my friend.