Fun video: A bowling ball and feather fall in world's biggest vacuum chamber

bowling-ball-featherNASA’s Space Power Facility in Sandusky, Ohio, is the biggest vacuum chamber in the world, measuring 30.5 meters by 37.2 meters, and has a volume of 22,653 cubic meters.  If you watched Commander David Scott drop a hammer and a feather on the televised Apollo 15 mission, then you probably already know how this one ends, but that doesn’t make watching it play out any less spectacular.

It was Galileo who first discovered that in a vacuum, if you were to drop two objects from the same height, they’d hit the ground at exactly the same time, regardless of their respective mass. In the atmosphere of Earth, we rarely – if ever – get to see this phenomenon. That’s where this big vacuum chamber comes in

British physicist Brian Cox wanted to see this  phenomenon play out in a vacuum, where there is zero air resistance to affect the acceleration of Earth’s gravity. This was filming done for the BBC 2 show, Human Universe,


newest oldest most voted
Notify of

That was very cool! Thanks for sharing it!! 😊

Bob F

And don’t forget, he is a 100% rabid warmist…


It’s required in his line of work.


And your point?

Gary Hladik

I can’t speak for Bob F, but I saw two possible points, if Dr. Cox is indeed a “100% rabid warmist”:
Cox either (1) is as gullible as anyone else, and does not really believe in his hero Dr. Feynman’s description of the scientific method (take nothing on authority), or (2) has no problem “stretching the truth” when it suits him.

Yes, Brian Cox is indeed a 100% AGW believer. You should read what Lubos Motl thinks of him. We should remember that Cox is just a TV performer. He hasn’t written any groundbreaking papers. He’s just the BBC’s male equivalent of a big pair of tits. He will be remembered when temps start to cool.

Janice Moore

Has to be #2, Mr. Hladik.
Anyone that un-photogenic who can get PAID to do stuff like that(!) may be dull, but he has “the dull cunning of the snake.”

Janice Moore

Also… the BBC, short on cash, is probably paying the man in windmill shares… MOTIVATION!
Producer: Go, boy, go! Push the ‘Human CO2 is Evil’ program for all you’re worth.

Big Jim Cooley says that Cox has written no ground-breaking papers. True, but on p95 of Cox’s book “Wonders of the Solar System” he writes that the diameter of Saturn’s moon Iapetus is 1.471km, and just to show that he means this, states it in Imperial: 0.912 miles. Now how the heck did they see such a tiny body in 1671? If he wrote that, then he’s an idiot; if he didn’t write it then what’s he doing putting his name to it?


– State-approved science demonstration at work. No CG animation required.
– Now demonstrate that global warming from 1977 to ~1999 was due to increasing pCO2 without a contrived CG animation.


He has to be.
It’s the reason he is the “go to scientist” for theBBC. They’d never use a “Denier”.

Mr Grace,
Not clear to me how that can be true (i.e. “100% Physicist”).
The theory of CAGW essentially predicts (yes this is a very brief and possibly poorly worded paraphrasing)…
>>We will have a tropospheric hot spot that will transport heat to the poles: oops, no hot spot according to observation (data 1: models 0)
>>We will continue to see global average temperature increase: oops, satellite temperature measurements (best approximation of something that can be called global average temperature) are flat in spite of 1/4 of all CO2 ever emitted by humans occurring in the past 18 years. (data 2: models 0)
>>Increasing violent weather: oops, tornados, hurricanes, droughts, etc globally are down. (data 3: models 0)
>>decreasing sea ice: oops, antarctic ice hits record high extent in the satellite era this year and has had a positive anomaly (above the baseline average) CONTINUOUSLY for the last three years. Arctic ice has grown from a minimum over the past two years. (according to Nobel Laureate Gore, arctic ice was to be at zero last year but MINIMUM arctic ice extent this year was more than SEVEN times the size of the state of Texas). (data 4: models 0)
>>Positive feedbacks due to increasing CO2 in the atmosphere: oops, no positive feedbacks otherwise the satellite measured temperature would be going up right now. (data 5: models 0)
>>Sea level rise will accelerate: oops, there are peer reviewed papers showing rate of sea level rise unchanged to actually decreasing/decelerating. (data 6: models 0)
>>Climate sensitivity to CO2 forcing is somewhere north of 3C for doubling of CO2 concentration: oops, based on observations (data), 41 peer reviewed papers now put this at 2C or less. (data 7: models 0)
I could go on with the absolute fail of this theory to have any predictive value. And your 100% Physicist is all in for CAGW?
Mr Grace, do I really need to paste in a link to Mr Feynman explaining how falsifying scientific theories works?
Mr Grace, do I really need to paste in a link to Mr Feynman explaining cargo cult science?
Could it be that under a thin veneer of physics that he’s really a politician? Or, he is a religious zealot? Or, is he just another example of an eco-loon who has educated himself beyond his IQ?
Just asking…

Mr Green Genes

Wrong. 80% physicist, 20% polemicist.
I have no doubt that he is a very intelligent man and, on most subjects in his field, is extremely knowledgeable and has the ability to put complex ideas over in a way that even I can understand. However, he has supped extensively at the kool-aid of CAGW. I genuinely don’t know if he actually means it, or if he’s come to the conclusion that to keep in the puiblic eye he needs to parrot the line. One thing’s for certain though, this former keyboard player with D:Ream does like being in the public eye!


It was stil a cool demonstration though. Cox is orthodox and his paycheque comes from the BBC. He is not going to bite the hand that feeds him as all he has to sell is his screen presence and his scientific background.
Beats working for a living I would say.


50% rock musician. 30% showman. 20% scientist.
Cox only came to the attention of the BBC because he had the ‘right-on’ credentials. He was a rock musician, and therefore ‘cool’. He was a liberal, and therefore ‘safe’. He was bright and photogenic, and therefore ‘sexy’. Phisics never came into it.
However, in praise of Cox, he had a right go at the BBC for favouring inane commentry over real science, in a recent live show. So much so, that his co-presenter had to shut him up. So well done that man – perhaps he has some science spunk in him after all.

Walt Allensworth

Wow, that’s one big vacuum chamber.

Jeff Alberts

It really sucks.

Anthony Hanwell

I like it!


but nature abhors it!


one explanation of his reasoning goes something like this … Take 3 cannon balls the exact same weight … hold them apart by several inches and drop them from a height. They will, as expected hit the ground at the same time … now weld 2 of the balls together and drop the welded (but weighting twice as much) and single ball again together … the 2 objects will still hit the ground at the same time … gravity doesn’t work on weight, gravity in fact creates weight … or at least our measure of weight …


It would be good to see an experiment to verify another counter intuitive gravity issue. Hold a pistol outstreched in one hand and a bullet in your other outstreched hand. Fire the gun and drop the bullet. They would hit the ground at the same time.
It would I suppose require a very big vacuum chamber and / or a very small popgun.

george e. smith

So was he expecting a different result.
That begs the question: is it possible to fly cast with a fly line and fly rod, while standing outside on the space shuttle ??
Why not ??


Sure it is… it would just take a different technique than what people are used to.

Bryan A

It also depends on the location of the Space Shuttle. The Endeavour is currently housed at the California Science Center in Los Angeles So fly casting there might be troublesome. In space though, you would need to be formly attached to the Space Station or orbiting Shuttle prior to the attempt due to Sir Isaac Newton’s 3rd law of motion.
That Equal but Poopsite reaction tends to rob 1/2 of the monentum from your Fly Casting Endeavour

Bryan A

Equal but OPPOSITE reaction rather than Poopsite


Yeah, truth be told, I kind of glossed over the ‘on the Space Shuttle’ part.

I got caught up trying to figure how the poopposite was going to get out of his space suite ….


I’d put a big roll in it, cut the line before it’s all the way out, and watch it roll away. If you cast in the direction of the orbit, it would move higher and fall behind me with respect to the earth. Opposite the orbit and it should fall below you and move ahead.
Either way, my body would start moving with respect to the shuttle in the direction opposite the cast, but it wouldn’t be by much and I’d be tethered. 🙂

george e. smith

Well it was a totally trick question. Fly casting has nothing at all to do with the weight of anything, it is all about mass and acceleration, and none of that is changed by the absence of gravity. In fact you can fly cast perfectly in the graviationless vacuum of space. The biggest problem would be in the design of the space suit, to allow free arm motion.
Fly casting, is about a massive fly line dragging along a massless fly, instead of having a massive lure dragging out a massless fishing line, as in conventional casting.
And yes, I have discussed this with Lefty Kreh.

Jeff Alberts

I just want to know how Poopsite ended up in Bryan A’s autocorrect dictionary.

Marilynn in NorCal

Brian, are you referring to this Poopsite?
or this one?
or perhaps this one?
So may Poopsites, so little time…


You would need something to trap the fly at the end of the cast otherwise it would snap back. It’s been 3 or 4 decades since I fly fished but I recall needing to lay that line down on the water and gravity along with surface tension hold it there… not gonna happen in a vacuum and microgravity.

You might have problems on the back cast if the hook penetrates your spacesuit. Don’t try this at home!


What you all are fly casting for?, gimme a bass lure and I’ll catch any thing up there, you know it’s all about trolling!


Please do not say “begs the question” when you mean “raises the question”. Begging the question is the name of the logical fallacy of assuming what you intend to demonstrate, as for instance IPCC does with its GIGO GCMs.
Pardon my being pedantic, but this growing misuse of the term annoys me.


A good example of why calling gravity a force just confuses the issue. Gravity is an acceleration, and the force is only a pseudo-force.



Actually, not quite, I believe…
F = d(mv)/dt = m*dv/dt + v*dm/dt (i.e. force equals the time derivative of momentum)
While dm/dt is zero in many physical problems (leaving F = m*dv/dt = ma), that dm/dt thingy (or mdot) is really important for rockets.


Gravity is a property of mass and two (or more) masses may impart an acceleration on each other due to that property.


Only in a Higgs Field.


I agree that calling gravity a force just confuses the issue, but disagree that the gravitational force is a pseudo-force. The force is real, just like other forces, for example the electrostatic force. Gravity is an acceleration field (gravitational field, g = F(g)/m). It’s just like the electric field, E = F(e)/q. F(g) is gravitational force, F(e) is electrostatic force, m is mass of the body in the gravitational field, q is charge in the electrostatic field.

I like the punchline at about 3:55. In a perfect vacuum extending down through the center of the Earth and back to surface on the opposite side, the ball and feathers would oscillate for many years. Is that falling?


Isn’t this what Hooke and Newton discussed in their famous exchange of letters in 1679?
There is in fact no effective gravity at the centre of the earth as the forces counteract each other.

Physics Major

The most accurate description of gravity is general relativity. In GR, mass curves space-time. Things move through curved space-time from point A to point B following the path of least space-time distance ( a geodesic). This is free fall. We feel a “force’ of gravity because our free fall has been interrupted by the electrostatic repulsion of the electrons in our feet trying to get close to the electrons in the floor. This is a constant acceleration that prevents us from continuing along a geodesic to the center of the earth. So, in GR there is no force of gravity, only forces that cause things to deviate from following the geodesic path of free fall.

Why are they acting so happy and surprised? For hundreds of years, we’ve known that this would be the result.


It goes hand in hand with Cox’ aforementioned denial of physics.

Bob B.

Careful how you say that. Sorry.


They are getting to play with an enormous, expensive, taxpayer funded toy in order to film a segment for a TV show, and they are being paid by the taxpayer to do it… of course they’re happy.

Yes, I was wondering how much money this “experiment” cost us taxpayers.

Better that than spending taxpayer money to figure out how to justify some sort of “carbon” tax! It’s on youtube, so its not like NASA will record over the tapes to save money like they did on the first moon landing, so it’s educational value will last for generations. You do have to admit that no matter how many times you say this is the result of dropping a bowling ball and a feather in a vacuum, actually seeing it at that scale is impressive.

The SPF is available on a full-cost reimbursable basis to government, universities, and the private sector.


I wondered the same thing. There was an even more expensive test video of that experiment shot on the moon, see here:


Yes but it was still amazing to see this happening which we know is true but counter-intuitive


“It was Galileo who first discovered that in a vacuum, if you were to drop two objects from the same height, they’d hit the ground at exactly the same time, regardless of their respective mass.”
Doesn’t that rely on one mass (earth) dwarving the test masses (balls and feathers)?
m1 and m2 are both in the equation for Fg, but you can toss m2 because it is diminishingly small (assumed to be).
I therefore call Galileo as quoted a liar.

Technically, Galileo could NOT have discovered this effect, though he might have theorized it.
Galileo was limited by the lack of experimental equipment (no watches, no clocks, no vacuum chambers, no precision mass balances,etc. He did PROPOSE the theory, but could only experiment with two balls rolling down an inclined plane.
But, the question: Does the “discovery” of a physics theory require a “proof”?

That’s not true. This experiment does not need a vacuum chamber unless you want to include the extreme, like a bowling ball vs feather or parachute. For most objects at modest heights, two balls of different masses hit the ground simultaneous regardless of air friction


Two balls of different size rolling down an inclined plane would be even more complicated, since a portion of their gravitational potential energy would be converted into rotational kinetic energy. You’d have to get the densities or mass distributions of the two balls ‘just right’ to get a scalable model where you’d the same proportion of rotational versus translational energy.
I may not have done all that well on my first midterm in my Kinetics class in college, but the tests on momentum and energy saved my bacon. Ended up with a solid A- in the class. And I ended up truly understanding calculus, once I had a practical application for it.

Robert Doyle

A wonderful gift to share with my grandchildren.
Thank you Anthony!

Brian Cox needs to get his physics correct.
Newton implied not only that force of gravity was moving the ball towards the floor, but however little the floor with the building, the Earth and the rest of the universe was moving towards the ball too.

The least you could have done was calculate the acceleration of the floor and the force on Brian Cox.
He was close enough, well within the range of measurement error.


I appreciate I may be getting repetitious so I apologise
Robert Hook proposed in 1666
”1. That all the heavenly bodies have not only a gravitation of their parts to their own proper centre, but that they also mutually attract each other within their spheres of action’.
2. That all bodies having a simple motion, will continue to move in a straight line, unless continually deflected from it by some extraneous force, causing them to describe a circle, an ellipse, or some other curve.
3. That this attraction is so much the greater as the bodies are nearer. As to the proportion in which those forces diminish by an increase of distance, I own I have not discovered it….”
In 1670 he further proposed that this force applied to “all celestial bodies” even if he did not postulatre universal gravity.
Like other people Hooke suspected that the force decreased with distance, probably an inverse proportion between gravity and the square of distance.
It was Newton, when prompted, who worked out the maths that proved it. Newton did not invent or discover gravity and was not the first to propose his famous laws. Newton did of course pioneer the concept of a mathematical approach to science. As a deeply religious man Newton was in fact somewhat troubled by the concept of univerasal gravity.

Michael E. Newton
November 4, 2014 at 12:11 pm
Why are they acting so happy and surprised? For hundreds of years, we’ve known that this would be the result.
November 4, 2014 at 12:11 pm
It goes hand in hand with Cox’ aforementioned denial of physics.
I suspect (although i could obviously be wrong) that their delighted reactions are because this is a stunning example of science at work.
When Galileo made his hypothesis there was absolutely no way it could be confirmed experimentally. There wasn’t the technology to form good enough large vacuums, let alone the camera and timing technology to confirm the result. In the 400 years since, technology has developed beyond anything he could have imagined, and can now confirm his result in such a simple and visual way. That’s the essence of science bin stunning slo-mo video.
The smaller minds of people like Mann are the ones that would go “meh, the models told us that already” at such a beautiful demonstration.

Wasn’t this theory proven when Galileo did his inclined plane experiments using spheres of varying mass?

Yes it was. Not the leaning tower of Pisa like its often shown.

Only indirectly – those experiments relied on the newfangled (at the time) algebra to translate the results for a freefall object. Show it to someone with no scientific or mathematical background, and you’ll have to explain why it means what it means.
They also introduced extra variables such as friction against the ramp, and the results were only accurate as far as measurements of the time allowed. Enough to confirm the result, maybe, but still only indirectly – almost, if you like, by proxy. And we all have views on those 😉
Dropping a feather and a ball through maybe 50 feet of almost perfect vacuum with high-speed photography monitoring them is as close to a direct test of the theoy as we’re ever likely to get. Hugely complicated technology but a perfectly simple experimental test with no extraneous factors to skew the results. Show it to anyone and they’ll understand what they see, which is scienctific confirmation at it’s most pure.


Pisa. My friend ….
i think even the Mann knew that.


It is a cool experiment, but I imagine at least a portion of the elation was on cue from the director.
Wish they had measured the ball’s velocity at impact under both conditions. I guess I could measure the time of each fall, derive the height using the time of the vacuum fall, and then determine the braking effect of the air; but that seems like a lot of work…..


Models are all well and good, but I still remember a black and white film of a feather some heavy object falling at the same speed from, oh, about fifth grade. Cox may have been able to do it on a bigger scale in a better vaccuum, but it’s been done before.

Noticing the indentation in the foam when they hit the bottom, I’m thinkin’ I’d rather be standing under the feather than the bowling ball, assuming I have a choice.
Just sayin’.


I wouldn’t want to be inside at all when they ran the test under vacuum.


Makes me wonder what a falling bowling ball would do to the helmet of a space suit.
Any volunteers?

the CAGW crowd never have fun….good video
off subject – artic ice update which is also fun to watch


I’ve been checking that daily too. Once the Red Line hits the little blue dotted line (by early/mid-December based on back of the envelope calculations), expect all sorts of MSM denials from NASA and NOAA “scientists” that it means nothing. They’ll all then scurry back to their caves and draw more circles on top of already epi-circles to explain it to their Congregations while asking for more money to study how warming makes more ice.

John Catley

Is this a case of hide the incline?

David A

Tony, of S Goddard fame, projected this a week or two ago. Since computer models project, as opposed to predicting, I thought skeptics should get equitable treatment.

Mark Bofill

:> Outstanding, I was talking to my little ones about this the other day. The video will help, can’t wait to show them!


Error here according to Wikipedia, Simon Stevin, a Dutch mathematician and physicist had previously
claimed that all objects falling in a vacuum would descend at the same rate. In reading of Galileo’s various theories, etc. we find a number of false beliefs he held – for example, his theories of tides were all wrong, while his contemporary Johannes Kepler correctly deduced they were due to the moon. He also refused to accept Kepler’s laws of planetary motion, which held their orbits to be elliptical, believing that only circular orbits would occur, since they were in heaven and a circle is perfect. He also was wrong in his belief of how swinging pendulums behave, something Christiaan Huygens discovered when he built he first pendulum based clocks. Huygens also realized that Saturn had rings, something that had confused Galileo. Galileo also observed, but failed to realize that Neptune was a planet, not a star. Galileo was one of history’s great scientists, but also an example that there have yet to exist any infallible scientists.


It’s interesting to note that this vacuum chamber can have a “cryoshroud” around the device under test, a high-absorptivity/emissivity shell that can be super-cooled to simulate the radiative conditions of space, eliminating the typical ~400 W/m2 “back radiation” that is present at typical earth ambient temperatures.
This is crucial for the proper thermal testing of space craft, which can only exchange energy with their environment by radiative means. It is very important to get the balance correct.

Remember seeing this on live TV about 40+ years ago: Hammer vs feather drop on the moon:

Joel O'Bryan

I think the amazing thing is that there obviously are BIRDS on the moon!!! Who knew?

Well, it was a Hollywood set and the feather was fabricated out of lead.

Stephen Richards

I worked for several years with a high vacuum ion implantation machine. I used to pump it down to 10^-6. It took a long time and was a chamber of about 3m3.
This room is just awesome and the pumps needed to get it down to a “perfect vacuum” (incidently impossible) must be just incredibly large and effective.
I used molecular pumps. God only knows what they were using.


They use “The Al Gore machine.” Mechanistically, that explains the Gore Effect on local weather as well.

Peter Plail

They needed some pretty big suckers, so I think they probably used a team of warmists.


What is the initial ‘blowback’ on the feather at the start of the 2nd fall? Incomplete vacuum? Electrostatic? Shouldn’t all parts of the feather accelerate at the same rate?


Gravity between the feather and the crane? A small disturbance by the release device? They should do a sequel.

Crane gravity way too small. I think they spliced the close up of the first fall to the beginning of the last.


Flex in the branches (flue) of the feathers, as they change from 1 G while hanging to an almost zero G state, while they fall…

What causes the flex? Every atom should fall at the same rate, even if they are not connected – that’s the whole point of the experiment.


bobby: Think carefully about upcountrywater’s argument. When the feather is attached to the bar, the branches are cantilevered (hanging) from the stalk, and the ends sag under the gravity. When the feather is released and the stalk falls, this sag disappears. And since the change is sudden, there is the possibility of “overshoot” in the reaction.
The next time you fly on a plane, get a window seat just behind the wing. When the plane is on the ground and the fuselage is holding up the wing, note the curvature of the wing. When the plane is in flight and the wing is holding up the fuselage, the curvature of the wing is very different. (In free fall, the curvature would be in between these.)

Jeff Alberts


Joel O'Bryan

The feather is an extended structure with weights suspended on elastic (a bio-polymer arm) barbs attached to the central shaft.
– As the feather is suspended by the shaft, the barbs are pulled down (flexed) by their own weight and of the associated feather material (called “hooklets”). This mechanical flexure in the extended structure generates the static opposing force (via mechanical stress in the bio-polymer) to the downward weight of each barb as it hangs in the vacuum at 1 g. Everything is in equilibrium prior to release.
-Soon as the shaft is released, the feather enters free fall, now experiencing zero g (as it is accelerating into the gravity well). This means the barbs now flex back to an unstressed (relaxed) state, they release the stored energy like a spring. You see the transient flex back to its relaxed state.

Yes, got it.

I noticed that too. Before its dropped, parts of it are sagging under the 1 g condition. After its dropped, and all parts of the feather are under zero g, those parts that were sagging a bit spring back a bit.
There is a very interesting high speed video on one of the interwebs showing a slinky under zero g as it falls; under various starting conditions and orientations.


Flex in the branches (flue) of the feathers, as they change from 1 G while hanging to an almost zero G state, while they fall…
bobbyvalentine466921 Says:
What causes the flex? Every atom should fall at the same rate, even if they are not connected – that’s the whole point of the experiment.
Let me try and clarify;
The main shaft of the feather is not under much of a flexing load as it hangs straight down.The branches (flue) are connected to the main shaft and are perpendicular to the shaft and are under a under a load of 1G,
At the moment of release, the load falls off to almost zero-G. The parts of the flue that were under load while hanging are now relieved the tension and compression forces equalize and the flue moves to it’s free fall (almost zero G) state.


I saw that too, figured it was ‘Moment of inertia’ (‘traagheid van massa’ as we say in Holland), but I could be completely wrong.

Crispin in Waterloo but really in Beijing

Scarface, I believe the extended components of the feather (as a group) rotate about the Moment of Inertia, the position of which can be accurately calculated (modeled) if you have a good enough description of the feather.
I was trying to be technically ‘general’ there. As there is no traction point involved I may be wrong.
What we can see is that the whole feather will tend to rotate about the Polar Moment of Inertia if there is any lateral stress on the clip holding it when it is released. Can someone confirm that this point does not have to be the centre of gravity, or does the fact that it is falling force it to be so?

That’s cool
My wife runs a summer science camp at the college for 7 to 11 year olds e. I built a glass vacuum chamber to play with. It does the feather/steel ballbearing drop. A little marshmallow astronaut demo (with and without clear plastic spacesuit, and shaving cream that bursts out of a plastic Easter egg. Has a large face vacuum gage calibrated with a biplane, a B-17, a jetliner, and sr71 looking thing and a space shuttle. Also has a little bell that goes silent.
My wife said it was a huge hit.


I wonder how they troubleshoot that giant container for tiny leaks.

I suspect its not really that great of a vacuum chamber, other than its size

10^-6 torr is pretty darn good…
and the chamber is also useful in letting Loki onto earth


Same as most trouble shooting for leaks in pressurized air/gas systems,just in reverse;
1) You can hear large leaks and the pumps will not be able to bring the pressure down
2) You spray a liquid on suspected leaks and it will “bubble” as air is drawn through it into the chamber
3) Dyes sprayed on the outside of the chamber/piping will be sucked in marking the leak path
4) Ultrasonic directional microphones can also amplify leaks and convert them to normal frequencies

M Courtney

Yes Cox is an anti-science warmist who openly asserts that sceptics are mad and dangerous.
But you’ve got to love this experiment. It confounds the poetic expectations of light and heavy objects with practical experience.
Just try to write a poem that describes the players (feather and bowling ball) and their race towards the centre of the earth. It always sounds like the tortoise and the hare – we instinctively know that this shouldn’t happen.
But that’s the way it is.

A few years ago – before he was the go-to scientist for the beeb – Cox, in one of his programs, said something I agreed with. It was something like:
“Cheap, reliable, and easily accessible energy is what makes civilisation.”
I agreed with him then.
I guess the corollary is:
“Expensive, unreliable, and hard to access energy destroys civilisation.”
‘Nuff said.

Philip Mulholland

Great to see the result a real physics experiment and not the output of a computer model masquerading as data.
From the same BBC2 episode of Human Universe –A Place in Time and Space – there is an interview with Astronaut Major General Bill Anders, the 1968 Apollo 8 Lunar Module pilot.
On passing into the Moon shadow he described the experience as follows:-
“The stars just exploded, I mean there were every star you ever thought about was visible, to the degree that it was very difficult to pick out constellations and yet as I look back over my shoulder the stars suddenly stopped and there was this big black hole and that was the Moon and I must say that got the hair on my back of my neck standing up a little bit.”

Why is this guy talking like he is tickled all the time, or on drugs, or talking to imbeciles, or something is wrong with him. Some kind of artificial, unnatural excitement squeezed out, over-sweet, saccharine. Can anybody but a far-out pervert make a career in BBC?

Thank you I have heard this guy before, I wasn’t sure if it his British accent or my hearing, or if he really sounds like that to other people. He sure sounds overly excited to be in a large room.


He comes from a place called Oldham in Northern England. We all talk a little bit like that, y’know, in Northern England.

John Catley

Professor Cox has made a name for himself and is well regarded by the BBC because he has the ability to make complex subjects easier for the TV audience to grasp. To some extent that requires him to adopt a condescending attitude. Having watched many presenters of science programs, I have to agree that Cox is quite good at what he does There are three earlier TV series – Wonders of The Solar System, Wonders of The Universe and Wonders of Life, all of which have received acclaim.
If off the wall presenters are to be discussed, I could nominate a boat load of them from “The Universe” on Discovery and other similar programs.
Perhaps it goes it goes the territory.

I’ve seen some of his “Wonders” series, and also was quite repelled by his over-exited, “talking to imbeciles” attitude. Acclaim? Not from me. I don’t like to be treated like a tawdry high-school run-of-the-mill idiot.

Björn from Sweden

Did Einstein really say falling objects do not move?


In a way, Yes. Measurement of velocity and acceleration depend on the Reference frame of the observer.
It is embodied in the Equivalence Principle in Einstein’s Theory of General Relativity.
Underlying all of that is the key Einstein insight that no matter the observer reference frame, all observers would measure the Speed of Light as a constant, c. i.e. the same value.

Gunga Din

In a way, Yes. Measurement of velocity and acceleration depend on the Reference frame of the observer.

I hope a cop doesn’t give me a speeding ticket while I’m sitting at my computer!
Or maybe he couldn’t catch up with me?
Does that mean I’m evading arrest just sitting here?
(Just in case someone couldn’t figure that out. I’d say “just in case they were slow” but maybe there’s no such thing?8-)


That wasn’t really Einstein’s insight. It had already been established by the Michaelson-Morely experiment. Einstein’s great epiphany was that time did not have to run at the same pace for all observers, and that resolved the conundrum of how light could appear to travel at the same speed for all observers.

No, he was trying to point out that the falling object does not experience acceleration. We, standing there watching it fall, describe it as acceleration, but that is because we ourselves are the ones in the accelerated frame. That is the acceleration that when multiplied by our mass, is the force that holds us against the earth! It is so obvious and was right under our noses the whole time till Einstein worked out the principle and carried it to its logical conclusion.

I don’t like this, I wanted to see it at full speed at least once. Because of the 1/6th gravity The David Scott moon experiment looks in slow motion. I want to see full speed so it looks like I expect things to look wehn they fall.

bruce ryan

remarkable you can evacuate 800,000 lbs of air and have only a few grams left.

David A

If those grams were just CO2, the whole chamber could have exploded.


The early scientists were satarised for trying to weigh the air.

Alan Robertson

That was fun.


I’ve always enjoyed watching him talk about things like the sun expanding to engulf the earth – he’s always so happy about the destruction. Seems to be a thing with the TV physisisisists (as my mother in law calls them).
Would have been really cool to see the whole drop at actual speed though.

Mike G

After what happened a Mann’s place of employment, this town in Ohio should consider changing its name.


I have to say that the whole concept is so counter-intuitive that it is positively miraculous that Galileo was willing to consider this as a possibility and undertake experiments to disprove his theory. Me, I would have just used a model and not bothered to do the empirical stuff after all models are always right and nigh-on impossible to disprove.

michael hart

Anyone know the evacuated volume, or evacuated diameter, of the Large Hadron Collider (LHC)?
I read that the circumference of the circle is 27 kilometers.

Crispin in Waterloo but really in Beijing

How big is the vacuum chamber at the Pickering Nuclear Power Station? It looks bigger than the NASA one.

Steve Oregon

Just last week I ran my own experiment. I put an alarmist and skeptic in a vacuum chamber to see if they would react differently.
The skeptic’s head exploded and it was quite messy. Grey matter all over the place.
The alarmist’s head merely expanded like an inflating balloon. For the sake of equality, and my research, I punctured the alarmists head. It did in fact pop like a balloon.
Never put live human research subjects into a vacuum.
Alarmists are air heads.
I was going to ask if someone would peer review my research but was afraid I’d get snipped if I went [too] far.


Fun video. It reminded me of a favorite riddle of mine when I was a kid.
Which weighs more; a ton of lead or a ton of marshmallows?

Jeff Alberts

Well, you’d certainly weight a ton after eating all those marshmallows.

FYI. Marshmallows in a vacuum chamber are a blast!


@ Steve R –
They’re more of a poof than a blast.

Jeff Alberts

What if they filled the chamber with CO2 instead?
Oh, right, they can’t. The universe would spontaneously combust.

James Strom

After seeing a few posts on this website bemoaning the lack of efforts to reproduce scientific claims, it’s good to see that experiment from 400 years back confirmed. My confidence in Galileo’s work has been boosted incrementally.

M Courtney

The more relevant point would be if the objects didn’t fall at the same rate. If the theory made a prediction that didn’t match reality.
That would be like the pause – proof that the theory was wrong.

James Strom

Yes, falling at different rates–that would be a real theory-popper, wouldn’t it?


There must be a cartoon somewhere of Galileo at the Leaning Tower of Pisa saying to someone “Of course the feather and the cannonball will land at exactly the same time, it’s basic physics”.

Björn from Sweden

It is alarming to see all deniers so impressed with this voodoo-science. Only a computer model can tell us what would happen in the experiment. My simulation shows that after 7 hours of free fall, a black hole opens up and swallows the ball and feather. This explains the bursts of gamma radiation that satellites frequently detect. I wil have the simulation peer reviewed and published in nature and it will magically become truth.

West Clintwood

Cox is a puerile pillock paid by the bbc warmistas.


In an article in the Guardian on 3 September 2014, Professor Cox states:
‘ … But what you’re not allowed to do is to claim there’s a better estimate of the way that the climate will change, other than the one that comes out of the computer models’
Is it any wonder, therefore, that we find him in the third episode of BBC2’s ‘The Human Universe’ giving uncritical airtime to the (in)famous Drake equation, aptly characterised by Michael Crichton as ‘… literally meaningless’?


Very poor production quality. Disappointing.


I was quite disappointed that they never showed the full drop at normal speed. It would take, what, 1-2 seconds? That’s way more impressive than slo-mo.
Here’s the feather/hammer video from the moon.


Woops. Someone beat me to it. Sorry.

Hey, I played your version just to see if it was the same. I think it’s OK to post this twice on this thread (worthwhile).

Great video and a great example of the physics involved for the lay audience, as well, I might add, of the tremendous impact of air resistance on objects generally.

Michael Larkin

So: they pump out all but 2g of the air. What happens to that remaining 2g? Is it evenly distributed throughout the chamber? It’s still millions if not billions of molecules, I suppose. I had this crazy notion that maybe they would fall like the ball and feathers (but during the evacuation period). Then I thought they’d still possess momentum and might be going in all directions.
Anyone care to enlighten me? I’m no physicist, unfortunately.

No, a few more than a billion actually.
You probably don’t want all of the molecular chemistry and standard gas law equations of analytical chemistry, but essentially, all gasses expand to fit into the space available. As they expand, their molecules move further and further apart, but the density remains “even” under normal circumstances near the earth’s surface. So, in this large room, the density of the 2 grams of air will be essentially uniform.
There are 2 grams in one “mol” of hydrogen H2. A weight of 1 in each hydrogen, times 2 hydrogens, ok?
There are 32 grams in one “mol” of oxygen O2. A weight of 16 in each oxygen 16 times 2 oxygens.
There are 28 grams in one “mol” of nitrogen N2. A weight of 14 in nitrogen times 2 nitrogens. See the pattern?
OK, well dried air is a mix of O2 and N2, with a molecular weight of 28.97.
Every gas “mol” has 6.022 x 1023 molecules in it. Look up Avogadro Law for the details.
So, 2 grams of hydrogen has 6.022 x 10^23 molecules in it, all zooming around the room at a near-perfect vacuum.
Air weighs more than hydrogen, so there are .415 x 10^23 “air molecules” in the chamber, all zooming around as pairs of nitrogen atoms and oxygen atoms.


That’s right. Dalton’s Law of Partial Pressure explains it.

Lloyd Martin Hendaye

Believe that Buzz Aldrin demonstrated this Galilean effect on his Apollo mission, dropping a golf ball and a feather simultaneously to the high-vacuum surface of the moon. His comment “This had better work” is an unsung Aristotelian classic… as a high-tech astro/engineer, just what in fact did he expect?


Does anyone know if bacteria could survive in such a vacuum chamber?


Positive about bacteria in general. They convert themselves to spores; in this form, their survival depends more on the presence of things that “go through” vacuum — photons and other particles that can damage them (although the idea of particles in vacuum seems a bit oxymoronic). Let’s say, most bacteria will survive “quiet” vacuum — without UV or “cosmic rays”.
Yeast can survive as-is (not to mention they ordinarily form spores as well). I have seen Aspergillus regrow from an electron microscopy sample, after having been frozen, metallized, and bombarded by electrons in vacuum.
Then there are Tardigrades, whose ability to survive both vacuum and exposure to solar radiation makes the successes of bacteria seem trivial.


A note to those folks who dig the coolness of this demo: there is one other effect that you can only see in vacuum, and it is just as spectacular, if not more; unlike balls and feathers, it is not part of our cultural background so it is truly surprising to see: in vacuum, liquids don’t splash.
Splashing is an atmospheric phenomenon; it weakens and even disappears in rarefied air, at about 1/3rd of atmospheric pressure. So I think it was a huge waste of vacuum (if I can say so) not to have dropped a gallon of water during the same event.


Tens of thousands of dollars spent to pump down and operate the largest vacuum chamber in the world to demonstrate a basic premise of physics known for hundreds of years. And to wreck a perfectly good bowling ball by drilling ANOTHER hole in it…
Your tax dollars at work.


Its called education and will no doubt be played at science classes. Worthwhile. You cannot help but be amazed and delighted by it.