Brian Cox visits the world's biggest vacuum | Human Universe - BBC

BBC

24 Oct 201404:41

Summary

TLDRThe world's largest vacuum chamber at NASA's space power facility in Cleveland, Ohio, simulates outer space conditions to test spacecraft. Originally a nuclear test facility built in the 1960s, it features a concrete skin for radiation shielding and external pressure resistance. The script describes an experiment akin to Galileo's, where a bowling ball and feather are dropped in a vacuum to demonstrate the true nature of gravity, free from air resistance. It takes three hours to achieve a near-perfect vacuum, after which both objects fall at the same rate, illustrating Newton's concept of gravity and Einstein's perspective that in the absence of other forces, there is no sensation of falling.

Takeaways

🚀 Nasa's space power facility near Cleveland, Ohio, is home to the world's largest vacuum chamber.
🌌 This chamber simulates outer space conditions by reducing air pressure to near-vacuum levels.
🏗️ Originally built in the 1960s, the facility was initially designed as a nuclear test site.
🛠️ The chamber's construction uses aluminum for radiation shielding and concrete for external pressure resistance.
📚 Galileo's experiment demonstrated that in the absence of air resistance, all objects fall at the same rate due to gravity.
⏱️ It takes three hours to evacuate the chamber of its 800,000 cubic feet of air.
🎥 The script describes a demonstration where a bowling ball and a feather are dropped in a vacuum to illustrate Galileo's principle.
📉 Air resistance is shown to be a significant factor in the rate at which objects fall in Earth's atmosphere.
🌍 Newton's theory of gravity is referenced, stating that a force pulls objects down towards the Earth.
🤔 Einstein's perspective on gravity is contrasted, suggesting that objects in free fall are not falling but are in a state of weightlessness.
📖 The script concludes by emphasizing that without the influence of gravity, there would be no way to detect the acceleration of objects towards Earth.

Q & A

What is the primary purpose of NASA's space power facility near Cleveland, Ohio?
-The primary purpose of NASA's space power facility is to test spacecraft in conditions that simulate outer space.
How does the facility achieve a near-outer space environment?
-The facility achieves a near-outer space environment by pumping out the air in the chamber until only about 2 grams remain out of the original 30 tons.
What was the original purpose of the facility when it was built in the 1960s?
-The facility was originally built in the 1960s as a nuclear test facility to test nuclear propulsion systems.
Why was the facility constructed with a concrete skin?
-The facility was constructed with a concrete skin to provide radiation shielding and to serve as an external pressure vessel to withstand the force present on the outside when the chamber is pumped out to simulate outer space conditions.
What is the significance of Galileo's experiment mentioned in the script?
-Galileo's experiment is significant as it demonstrated the principle of gravity, showing that in the absence of air resistance, all objects fall at the same rate regardless of their mass.
Why did the feathers fall slower than the bowling ball in Galileo's experiment?
-The feathers fell slower than the bowling ball due to air resistance, which affected their rate of descent.
How long does it take to create a near-perfect vacuum inside the chamber?
-It takes three hours to pump out the 800 thousand cubic feet of air from the chamber to create a near-perfect vacuum.
What is the significance of the phrase 'We drop the millet in the last 30 minutes'?
-The phrase indicates that the final preparations for the vacuum test occur in the last 30 minutes before the actual drop test, ensuring the vacuum is complete.
What does the term '6104 Manual 10 percent Orbit Station One go for Drive PCB' refer to in the script?
-This term refers to a series of commands or procedures being executed to prepare for the drop test, indicating that the system is ready to proceed with the experiment.
What does the pressure set point at 240 PSI signify?
-The pressure set point at 240 PSI signifies the target pressure that the chamber should reach before the drop test can commence.
How do Newton's and Einstein's views on gravity differ as described in the script?
-Newton believed that gravity was a force pulling objects down, while Einstein imagined that in the absence of other forces, objects in free fall are in a state of weightlessness and are not accelerating towards the Earth.

Outlines

00:00

🚀 Space Power Facility and Vacuum Chamber

The script describes NASA's Space Power Facility in Cleveland, Ohio, which houses the world's largest vacuum chamber. Originally built in the 1960s as a nuclear test facility for propulsion systems, it is now used to test spacecraft in conditions that simulate outer space. The process involves removing nearly all air from the chamber to create a near-perfect vacuum, which takes about three hours to achieve. The chamber is constructed with a concrete skin that serves as both radiation shielding and an external pressure vessel to withstand the vacuum's effects.

🌌 Galileo's Experiment on Gravity

The script recounts Galileo's famous experiment demonstrating the principle of gravity. It explains how, in the presence of air, a heavy object like a bowling ball and a light one like a feather fall at different rates due to air resistance. To observe gravity in its purest form, the script describes an experiment conducted in the vacuum chamber where both objects are dropped and fall at the same rate, illustrating that in the absence of air resistance, all objects accelerate towards Earth at the same rate.

🌌 Newton vs. Einstein on Gravity

The script contrasts the views of Isaac Newton and Albert Einstein on gravity. Newton believed that a force, gravity, pulls objects downward. Einstein, however, envisioned gravity differently. He theorized that objects in free fall, like the bowling ball and feather in the vacuum chamber, are not actually falling but are in a state of weightlessness. According to Einstein, they appear to accelerate towards Earth only because there is no other reference frame to indicate that they are standing still in a curved spacetime caused by Earth's mass.

Mindmap

Keywords

💡Vacuum Chamber

A vacuum chamber is a space from which air or other gases have been removed, creating a vacuum. In the context of the video, NASA's space power facility near Cleveland, Ohio, houses the world's biggest vacuum chamber, which is used to simulate outer space conditions for testing spacecraft. The vacuum chamber's purpose is to remove air resistance to study the effects of gravity in a controlled environment, as demonstrated by dropping a bowling ball and a feather to show that they fall at the same rate in the absence of air resistance.

💡Spacecraft Testing

Spacecraft testing involves evaluating the performance, safety, and functionality of spacecraft components under conditions that simulate space. The vacuum chamber at NASA's facility is critical for spacecraft testing as it allows scientists to observe how spacecraft would behave in the vacuum of space, free from the influence of Earth's atmosphere.

💡Nuclear Test Facility

A nuclear test facility is a site designed to conduct experiments related to nuclear reactions or propulsion systems. The video mentions that the vacuum chamber was originally built in the 1960s as a nuclear test facility. This historical context is important as it shows the evolution of the facility's purpose from nuclear testing to space exploration, reflecting changes in scientific priorities and technological advancements.

💡Radiation Shielding

Radiation shielding is a material or substance used to block or reduce the passage of radiation. The video explains that the vacuum chamber was constructed with a concrete skin that serves as part radiation shielding. This is crucial because during nuclear tests, shielding is necessary to protect the surrounding environment and personnel from harmful radiation.

💡Gravity

Gravity is the force that attracts two objects with mass towards each other. In the video, the concept of gravity is central to the experiment conducted in the vacuum chamber. By removing air from the chamber, scientists can observe the true nature of gravity as it acts on objects without the interference of air resistance, as demonstrated by the simultaneous fall of a bowling ball and a feather.

💡Air Resistance

Air resistance, also known as drag, is the force that opposes the motion of an object through the air. The video script uses the example of a feather falling slower than a bowling ball in normal atmospheric conditions due to air resistance. In the vacuum chamber, air resistance is eliminated, allowing for a clearer demonstration of gravitational forces.

💡Galileo's Experiment

Galileo's experiment, mentioned in the video, is a historical demonstration of the principle that objects of different masses fall at the same rate in a vacuum. The video references this experiment to set up the scenario where a bowling ball and a feather are dropped in the vacuum chamber to show that they fall at the same rate, illustrating Galileo's findings.

💡Einstein's Theory of Relativity

Einstein's theory of relativity, particularly his 'happiest thought,' is alluded to in the video. It challenges the traditional view of gravity by suggesting that objects in free fall are not actually falling but are in a state of weightlessness, moving along a straight path in the absence of other forces. The video script contrasts Newton's and Einstein's views on gravity, highlighting the shift in scientific understanding.

💡Orbit

Orbit refers to the path of an object in space as it moves around another object due to gravity. The term '10 percent orbit' mentioned in the script likely refers to a setting or condition within the vacuum chamber that simulates a fraction of the gravitational conditions experienced in space. This term is important as it relates to the broader context of space travel and the conditions that spacecraft must endure.

💡Pressure Vessel

A pressure vessel is a closed container designed to hold gases or liquids at a pressure different from the ambient pressure. In the video, the vacuum chamber's concrete skin serves as an external pressure vessel, capable of withstanding the external forces when the chamber is evacuated to simulate the vacuum of space.

💡Pumping Out Air

Pumping out air refers to the process of removing air from a confined space, such as a vacuum chamber. The video describes how it takes three hours to pump out 800,000 cubic feet of air from the chamber to create a near-perfect vacuum. This process is essential for achieving the experimental conditions necessary to study the effects of gravity in isolation.

Highlights

Nasa's space power facility near Cleveland, Ohio, is the world's biggest vacuum chamber.

The chamber is used to test spacecraft in conditions simulating outer space.

The process involves pumping out 30 tons of air until only about 2 grams remain.

The facility was originally built in the 1960s as a nuclear test site.

Aluminium was chosen for construction due to its radiation shielding properties.

The vacuum chamber is reinforced with a concrete skin for external pressure resistance.

Galileo's experiment is referenced to demonstrate the effect of air resistance on falling objects.

In a vacuum, a bowling ball and feather fall at the same rate, illustrating the true nature of gravity.

It takes three hours to achieve a near-perfect vacuum by removing 800 thousand cubic feet of air.

The final 30 minutes of the process involve dropping millet to prepare for the experiment.

The vacuum chamber is pressurized to 240 PSI before the drop.

The bowling ball and feather are dropped to demonstrate the absence of air resistance.

The simultaneous fall of the bowling ball and feather confirms the theory of gravity.

Isaac Newton's theory of gravity is explained through the falling objects.

Einstein's perspective on gravity is contrasted with Newton's, emphasizing the lack of force on the objects.

Einstein's 'happiest thought' is described, suggesting objects in free fall are in a state of weightlessness.

The conclusion is that in the absence of air resistance, all objects fall at the same rate due to gravity.