00:01I can't believe it. The Earth's inner core has supposedly stopped rotating and
00:06changed direction. That's what a recent news report says. Surprising, isn't it?
00:11How could the core just stop rotating, man? If it stops, we're all in trouble.
00:16Hurricanes, floods, cosmic rays, God knows what awaits us. Actually, it's much
00:21simpler than that. The Earth's inner core is a solid metal ball deep inside the
00:26planet. You'd expect it to rotate in sync with the Earth's outer layers. That
00:31seems more intuitive, right? But that's not the case. This core spins a little
00:36faster or slower than the outer layers in a 70-year cycle. Sometimes the core gets
00:42ahead, other times it falls behind the outer layers. The difference in rotation
00:47is small and could only be measured by studying the seismic waves from massive
00:52earthquakes and their reflections caused by Earth's solid core. So this is
00:56about the relative movement between the rotation of the core and the outer
01:01layers. The accurate headline should have been something like this. The Earth's
01:05inner core has slowed its rotation compared to the outer layers, but it
01:09continues to spin at a dizzying speed. A piece of news that will be repeated in
01:1670 years. Leave a comment with your opinion about this misunderstanding.
01:23Another young man electrocuted on the train car. Don't do such a thing. If you
01:26think you only get electrocuted if you touch the wire, you're wrong. You are at
01:31risk of electrocution from the moment you climb onto the train car. Didn't you know
01:35that? Well, remember, you can get electrocuted even without touching the
01:39high voltage wire. It's enough to be just a meter and a half away from it. As
01:43someone once said, I know the wire has 27 kilovolts. I know electric current flows
01:48between the wire and rail to power the locomotive, and if I touch the wire, the
01:53current would pass through me to the rail, electrocuting me. But that's not all. The
01:58high voltage wire ionizes the air around it, and if you climb on the wagon, you
02:03basically become a lightning rod for the train. That means an electric arc forms
02:07through the air, and the current flows from the wire, through the air, then through you, to the
02:13ground where the rails are, even if you're one meter away from the electric wire.
02:18As a result, you'll be electrocuted instantly even if you didn't touch the
02:22wire. It'll be like a lightning strike. So, dear friends, don't go anywhere near
02:27high voltage power lines. Don't come close to them. That's why they're marked like
02:32that. You can get electrocuted even from a distance. Here's what can happen.
02:38This is a NASA simulation of a flight into a supermassive black
02:42hole surrounded by a disk of hot glowing gas. For the camera, time slows down
02:48compared to that of a distant observer. It's now moving so fast that the
02:52simulation slows down to see it better. The speed of the camera makes the light
02:57sources directly ahead much brighter. Now the camera begins its 10-minute plunge
03:02toward the event horizon. The event horizon is a spatial boundary beyond which
03:08nothing, not even light, can escape from the black hole. The camera reaches the
03:13event horizon. Now, light from outside the universe still shines in, but it can never
03:19leave. The film camera is a device. Microseconds later, it reaches the singularity.
03:27Because of turbulence in the air, a man was thrown into the overhead bin and
03:31got stuck there. How is that possible? Most often, turbulence in the air occurs
03:36because of unpredictable movements of air masses, which pilots can't see because
03:40the air is transparent. Normally, the airplane is kept in the air by its lift
03:45force. The air that flows faster over the top of the wing, the koanda effect, creates
03:51lower static pressure. And then, the air pressure on the underside of the wing
03:55efficiently pushes the airplane upward, overcoming the force of gravity acting on
04:00the airplane. The air resistance on the top side is now lower. However, the air is
04:04not still. Sometimes it stays in place. Other times it creates air currents and
04:08sometimes even vortices or turbulence. In this case, the air pressure will
04:12suddenly change on both wings and the airplane starts to behave like a car driving
04:17on a bumpy road. The passengers are thrown either upward or to the left
04:21or right by the inertial forces, just like it happens in a car. Without a seatbelt, it
04:26can be dangerous. What is recommended? Wear your seatbelt. If you're afraid, choose a
04:31seat in the center of the plane near the wings where turbulence is felt less. As a
04:36last resort, fly in the morning. Daytime flights often have more turbulence due to
04:42warmer air. Have you experienced this during a flight? We live in an internet world, but
04:47the internet we see today is seen differently by the people living on this
04:50planet. When I want to travel virtually and I'm curious about how the world looks
04:54in those countries, I use a VPN. Surfshark is a VPN that gives you access to
04:59the entire Netflix movie database and cheaper subscriptions to some platforms,
05:02YouTube, Premium, HBO, etc. Surfshark hides your IP address and thus ensures your
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05:48This is a real picture of a quasar recently taken by the James Webb Telescope.
05:52It looks like a ring. The three dots at the top are the same image of a quasar
05:56located six billion light-years away. That quasar you're looking at right now is a
06:02supermassive black hole that devoured the surrounding stars six billion years ago.
06:06The stars were pulverized, ending up falling into the black hole through a
06:10very bright accretion disk. That's the light you're seeing. Goodbye stars. But why
06:16do we see three images? Actually four. There's another one below. Because the
06:20light from the quasar before reaching us passed by a galaxy which appears blue in
06:25the center. This galaxy has distorted the space around it and the light rays were
06:30bent. This effect is known as gravitational lensing. Because of this bending of the
06:35light rays, the light from the quasar reaches us from four different
06:38directions. These are the four dots in the image. Moreover, the images of the
06:43quasar are magnified and the rays do not arrive in sync but at different times.
06:48With this information, astronomers measured the accretion disk's radius. It is
06:53only three times larger than the radius of the black hole's event horizon. From this,
06:57astronomers deduced something extraordinary. The black hole rotates
07:01around its own axis at a speed that at the event horizon is half the speed of
07:05light. Look at this image once again. There truly is another world there. Distant and
07:11strange to grasp. You can't believe this. They built the most precise atomic clock. It
07:18only loses a second every 30 billion years which is twice the age of the
07:23universe. Amazing! Instead of using the well-known atomic clocks based on microwaves,
07:29this clock uses visible light which vibrates thousands of times faster than
07:34microwaves. The clock is more precise. How does it work? By trapping tens of
07:38thousands of strontium atoms in a lattice of laser beams. The atoms are
07:43cooled to incredibly low temperatures, microkelvin, so they don't escape from the
07:48optical tweezers of the laser beams and in this way they preserve their
07:51delicate quantum states. In these states, the atoms have precise quantum
07:55transitions determined by their energy levels. Truly what's amazing is that this
08:00clock can detect the tiny changes in time dilation caused by gravity. Any clock
08:05lowered by the thickness of a human hair will lag by a few thousand billionths of a
08:11second. Did you notice that? I don't think so. But does the new clock measure
08:16something like that? Do you realize what possibilities could open up? From
08:20understanding the effects of gravity on microscopic quantum states to exploring
08:25the mysteries of dark matter and dark energy by precisely measuring what
08:30happens in the cosmos, what would you measure with a watch like this? This was
08:37filmed today over Romania Sunday at 9.25 p.m. It's clear that something is burning
08:43in the atmosphere because the front part is bright and there's a tail behind it but
08:47is it a meteor or space debris? How can we tell them apart? Well, by their speed.
08:53Meteors are cosmic rocks that enter the atmosphere at speeds greater than 10
08:58km per second, even higher than 30 km per second, which is Earth's orbital speed.
09:04On the other hand, space debris enters the atmosphere at a speed determined by its
09:08orbital velocity, 7 to 8 km per second, which is lower. Since this trail was filmed in
09:14real time, it means it moved slowly, which means it was a piece of space debris. It
09:19is now known that it was Starlink 1196, a non-functional satellite from Elon Musk's
09:25satellite constellation, which re-entered uncontrollably and disintegrated above the
09:29Balkans. Did you find any pieces of debris from it in your yard? Thank you for
09:34watching my video until the end and thanks to Surfshark for sponsoring. Don't forget
09:38about my link in the description. That way you ensure your privacy with Surfshark and
09:42get four months free. Until next time, I'm Christian Presura,
09:45Fisica Povestita. You are cool. I wish you all the best. Goodbye!
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