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rancherbill
07-17-2009, 01:16 PM
Canadian Guys

There is is alway interest in space. This Sunday on Discovery Channel is, IMHO, one of the Top Ten documentaries of all time

Journey to the Edge of the Universe (http://www.discoverychannel.ca/Showpage.aspx?sid=14312) you can also watch it online.

Fasttrack
07-17-2009, 01:23 PM
Be suspicious. You may not believe the number of times there have been blatant errors in both the History Channel and the Discovery Channel programs, to say nothing of inaccuracies or "lie by omission" type mistakes. They are great programs for entertainment, but don't take anything too seriously.

It is a problem that the scientific community has been working very hard to fix - television producers want drama and a show that sells, not science. Often the information is manipulated and incorrect.

Nevertheless, it is far better programming than some of the trash on the tube these days... :D

Evan
07-17-2009, 06:18 PM
The title alone is highly misleading. The edge of the universe is beyond our event horizon by a very large amount. We can never reach it even traveling at the velocity of light since it initially expanded at a velocity far higher before all the "rules" froze in place. You can't go there and you can't see it but if our current understanding of the initial expansion phase is at all close to correct there is "stuff" out there that is originally of this Universe.

Don't ask what is beyond that as it represents "time" before the big bang. I forgot who said it but when asked that question a famous scientist replied "God made hell for people that ask that question". :D

tattoomike68
07-17-2009, 07:02 PM
The big bang theory is every bit as Kooky as the beared man in the sky made everything.

If you ask me some people just smoke WAY TOO MUCH DOPE.

Evan
07-17-2009, 09:22 PM
The reason the Big Bang hypothesis was developed was because there is a lot of observable evidence that can't be explained any other way. The evidence came first and then the cosmologists tried to find a way to explain it. Big Bang with a number of modifications from the original concept is the best explanation there is to date. Nothing else even comes close.

Your Old Dog
07-17-2009, 09:30 PM
Be suspicious. You may not believe the number of times there have been blatant errors in both the History Channel and the Discovery Channel programs, to say nothing of inaccuracies or "lie by omission" type mistakes. They are great programs for entertainment, but don't take anything too seriously.

It is a problem that the scientific community has been working very hard to fix - television producers want drama and a show that sells, not science. Often the information is manipulated and incorrect.

Nevertheless, it is far better programming than some of the trash on the tube these days... :D

ditto that. Hard to believe a program by the name of "history", which to me imparts data, fact and evidence can be so strewn with inuendo, opinion and half-truths can be presented as fact. Talk about agenda driven media. I now question everything I've seen or heard on National Geographic Channel

doctor demo
07-17-2009, 09:39 PM
.

If you ask me some people just smoke WAY TOO MUCH DOPE.
How much is too much? Er a I'm asking for a friend, ya thats it... a friend.

Steve:D

tony ennis
07-17-2009, 09:43 PM
Don't ask what is beyond that as it represents "time" before the big bang.

Assuming "time" has a meaning before the BB.

doctor demo
07-17-2009, 09:46 PM
The edge of the universe is beyond our event horizon by a very large amount. We can never reach it even traveling at the velocity of light since it initially expanded at a velocity far higher before all the "rules" froze in place. ". :D

Evan, I'm asking this....not to start a debate as I am not up on this stuff.
Doesn't the String Theory allow for the edge to be reached?

Steve

tattoomike68
07-17-2009, 10:58 PM
How much is too much? Er a I'm asking for a friend, ya thats it... a friend.

Steve:D

5 grams of killer a day is too much. you best be sharing.

tattoomike68
07-17-2009, 11:04 PM
The reason the Big Bang hypothesis was developed was because there is a lot of observable evidence that can't be explained any other way. The evidence came first and then the cosmologists tried to find a way to explain it. Big Bang with a number of modifications from the original concept is the best explanation there is to date. Nothing else even comes close.

So a microdot went BOOM and made everything, thats just as crazy as god making everything.

Both types ate too many microdots of LSD 25 and never came down. I take back what I said about pot smokers.

Evan
07-18-2009, 01:12 AM
So a microdot went BOOM and made everything, thats just as crazy as god making everything.


But, we are here. So is the Universe. To me it's all highly unlikely too. So is winning the lottery. Perhaps the only thing more unlikely is to assume this all has been and will be for infinite time, a condition required of the Steady State Hypothesis. Funny thing, Big Bang doesn't rule out God either, one can always posit that it was His work. It's as good an explanation as anything else, which is to say we don't have an answer and cannot discover why this all exists. One thing to realize is that no matter how improbable an event may be if it isn't ruled out then it may happen. When it happens the probability collapses to 100%.

Steve,

String Theory is very undeveloped. It makes no testable predictions about the real world. Until it does it isn't even a hypothesis, never mind a theory.

Tony,

Time has no meaning at the quantum level now, never mind then. Events are reversible and only a very special type of interaction has a preferred direction which displays an irreversiblity giving rise to what is called the "arrow of time"

As Einstein said "Time exists to prevent everything from happening at once".

rancherbill
07-18-2009, 08:41 AM
Would you guys crank down the discussion of whether any TV program is as accurate as a Post Doc seminar.

It's entertainment that also educates. It's 'Astronomy for Dummies' and I'm a dummy. When I was in High School no one had walked on the moon and an atom just had three parts.

This program integrates all those pretty Hubble pictures, and others, into a program and explains to lay people what the heck they are.

Not starting an argument. I read somewhere in a 'Dummy' magazine 'time does not exist' in physics. Some guy works at 10^-43 (??) seconds. At that level there is no time, only states. If he makes a series of observations of the state, there is a change in states, which the people call time. What is happening that causes electron's state that cause it to orbit the nucleus? Orbiting is not caused by the four forces in nature. There see - that's something I picked up on these science for Dummies shows - the four forces of nature.

What are they?
Which one is lower that expected?
Why?
What will you do with all the science groupie chicks, if you can answer the third question?

tony ennis
07-18-2009, 09:11 AM
So a microdot went BOOM and made everything, thats just as crazy as god making everything.


Those two suppositions aren't mutually exclusive.

rotate
07-18-2009, 10:08 AM
Although there's lots of misinformation in these science shows, I think it still serves a valuable purpose. It gives general public (at least those public that watch these type of shows) a better idea that the universe that we live in is "knowable" to a great extent. The alternative is ignorance, superstition, and silly religious tales.

Evan
07-18-2009, 10:37 AM
What are they?
Which one is lower that expected?
Why?
What will you do with all the science groupie chicks, if you can answer the third question?


Gravity, electromagnetism, strong force and weak force. But there are really only three since at high energies the electromagnetic and weak forces unite to become the electroweak force.

Gravity. Oddly enough although it is by far the weakest of all the forces by a huge amount it is also the one that ends up overcoming the others.

Why? Nobody knows. Nobody knows how gravity really works at all. We don't even know how fast it propagates for sure.

In my experience they don't really care if you know the answer. :D

Fasttrack
07-18-2009, 12:20 PM
Really there is only two. The coupling constants can be run to just one point in r-parity conserving SUSY (SU(3), for instance). Plus it explains mass and dark matter and matter/anti-matter asymmetry and solve other hierarchy problems in the standard model. There are several viable models for gravity right now, although none of them is really "satisfactory" by physicists' standards.


I will say that the science shows at least encourage enthusiasm for the sciences, which is important. But it is also important that viewers be a responsible audience and realize that the program they are watching is not neccessarily accurate. I think that is less of an issue with people on this forum than it is with some other groups of people.

Fasttrack
07-18-2009, 12:21 PM
In my experience they don't really care if you know the answer. :D


Damnit - all my hopes thrown out the window... :D

Evan
07-18-2009, 01:27 PM
Damnit - all my hopes thrown out the window...

You are taking that the wrong way. The don't call it the student union for nothing. Just go sit for a while with a dense textbook and pretend to study. Make sure the title is visible. Something entirely obscure such as "Transport Phenomena by Bird, Stewart, Lightfoot" will get attention (It's on my shelf, all about heat flow :D). Make sure there is room beside you.

If you wait they will come.... :D

BTW, if you need to buy that book for any of your courses you can have my copy. The most recent edition is $152 CDN. :eek:

Fasttrack
07-18-2009, 09:13 PM
LMAO - thanks for the tip ;) :D

Luckily the only thermodynamics class I have left to take uses a book that is no longer in print. We pay $8 for it - most of which goes to pay for a xerox copy and the other $2 goes to the publisher for rights to copy the book. Not sure why we haven't changed books, but I guess I won't complain since that's about the cheapest text book I'll ever buy. Thanks for the offer though! Text books sure can add up in a hurry!

oldtiffie
07-18-2009, 09:30 PM
There are some - many?? - outside the USA - of course - who will tell you that so far as they can ascertain from the "noise" that the end and beginning of the world and the universe and the centre of creation is the big black hole inside the US continental shelf (or is it the high or low water line/s?).

Or is it just introspection?
http://en.wikipedia.org/wiki/Introspection

Or retrospection?
http://en.wikipedia.org/wiki/Rosy_retrospection

Or just "noise"?
http://en.wikipedia.org/wiki/Noise

Your Old Dog
07-19-2009, 10:05 AM
Although there's lots of misinformation in these science shows, I think it still serves a valuable purpose. It gives general public (at least those public that watch these type of shows) a better idea that the universe that we live in is "knowable" to a great extent. The alternative is ignorance, superstition, and silly religious tales.

Nah, it's worse then that. It causes society in general to be afraid to question for fear of being made an outcast. How many bright young scientist are out there telling us all that global warming crap is based on junk science? Not many. But there are many senior scientist making the junk claim. That's because the young have their careers in front of them and can't risk the ridicule of others who have already bought into it. One good belch from a volcano that spreads ash around the globe would do us in anyway much faster then global warming. Not only that, as people we will adapt to global warming just like we've been adapting to the planet since time began. That's only part of the tale.

Here's another aspect of mass media. It's vital that these programs keep professing doom as that's what sells. You have to keep telling people that the world is near it's end either from global warming, aids, earth quakes, volcanos and astroids. People are controlled better with fear then with comfort. All this doom and gloom starts to stick in the minds of the people. It's "advertising", we just don't call it that but minds are being led to buy into a thought the same as a product and it frequently goes against whats best for all. Will more people gain jobs from the "green" bs then will loose them?

Fasttrack
07-19-2009, 01:29 PM
LOL - is anyone here familiar with the story behind the two students who proposed that electrons have intrinsic spin? (Uhlenbeck and Goudsmit)

Their advisor told them to submit their paper for publication because they were young and could afford to be wrong. In physics, as the physicists become older they tend to become more conservative in their claims as they have a reputation to uphold. Students, on the other hand, have no reputation and can risk being wrong - at least according to their advisors. :)

Evan
07-19-2009, 02:22 PM
I hate the word "spin" as it applies to electrons. It gives an image of a toy top madly spinning on the floor. Then you need to figure out how it can be up spin or down spin. That's not too bad but what the heck is half spin? :D

I much prefer the naming conventions for quarks. They make absolutely no sense at all which is entire in keeping for something that can only be inferred to exist.

Fasttrack
07-19-2009, 03:10 PM
Well half spin is just a matter of units - namely half h-bar. That never bothered me, but the concept of intrinsic spin is misleading. So, too, are the colors of quarks but they both have their place.

Incidently, quark confinement is not directly provided in QCD. There is alot of work going on to refine the field theory so that quark confinement is directly predicted by the theory. It turns out that there may be some analog to models for superconducting single pole magnetic fields (of course single pole magnets are theoretical, only!) But there seems to be a tantalizing similarity that gives us GUT enthusiasts some hope that we are on the right track in our belief of some larger unity.

I don't know alot about the subject myself, but I had the good fortune to speak with some QCD folks here during a dinner party. Very interesting theoretical work being done right now. I'm working on the ATLAS detector, trying to improve reconstruction of missing energy so I don't get into the theory very deeply.

Evan
07-19-2009, 04:13 PM
But there seems to be a tantalizing similarity that gives us GUT enthusiasts some hope that we are on the right track in our belief of some larger unity.


You mean such as gravity I presume, which as far as we know is strictly monopole. I personally KNOW there must be a GUT theory that works. We happen to be living in the middle of extremely compelling evidence. :D

Teenage_Machinist
07-19-2009, 06:07 PM
I find this thread pathetically hilarious


1. Actually string theory IS testable but we will not have the tech to test it very will for a long time. The Large Hadron Collider is part of that.
2. The universe does not have an edge. It goes on forever. One of the central assumptions of cosmology is that the universe is homogenous, but we are in the middle of a low-density zone, that could explain the rather weird "acceleration".
3. Laypeople should not bash well-validated, though weird, theories based on their apparent absurdity.
4. The views of the scientific community on global warming are NOT propagandized whether or not the danger is exaggerated or downplayed by politics. Astroid strikes are a risk, easily solvable with thruster packs, or, in a pinch, thermonuclear weapons in conjunction with an early warning system.
4. Dissent is an essential part of science, though unfortunately things can occasionally become dogmatic. However, our science is much more complete than it was, and many movements seem to me like a kind of denialism. I believe that global warming and depletion of resources pose a very severe danger to "homeworld security" but it is easily within our grasp to solve this problem through a great project that would generate hundreds of millions of jobs and possibly elevate the starving millions to a state of civilization.

I do not see, in addition, why you care about those jobs. When October has come, you will only care whether or not global warming prevents enough food from being grown.

Fasttrack
07-19-2009, 06:57 PM
I find this thread pathetically hilarious


1. Actually string theory IS testable but we will not have the tech to test it very will for a long time. The Large Hadron Collider is part of that.


Actually no. The LHC was built primarily to detect the Higgs Boson, although the Tevatron has a shot at that, now. Next up on the list is SU(3) stable particles. Evidence for string theory will be non-conclusive and suggestive, at best. In fact, the only really viable string theory models depend upon the gauge symmetry of SUSY models. There are no directly testable predictions from string theory. The only way that string theory and the LHC are related is that string theories have a lot of "if's" that must be satisfied for the theory to be viable. The LHC will be examining those "ifs".

3. That gives the scientific community a bad name and I would appreciate it if you amend your statement. We are not "gods" and we are just as likely to be wrong as the next person. We try to promote communication between "laypeople" and the scientific community and the first step to doing this is to recognize that we are all people and we all have a right to our opinions, however misguided. Unfortunately, it has been estimated that 80% of the American population is "science illiterate". :( Our goal is to involve more people and teach them the basics of scientific reasoning. The reason why people bash theories is because they don't understand them. The best way to solve this problem is to educate them. "Open-mindedness" is important for both parties.

You might also check your numbering :)

Evan
07-19-2009, 07:16 PM
1. Actually string theory IS testable but we will not have the tech to test it very will for a long time. The Large Hadron Collider is part of that.
As I first said and as FT confirmed, String Theory makes no predictions about matter and energy that we can test.

2. The universe does not have an edge. It goes on forever.

If the Big Bang or any variation of it is correct then it does have an edge. We can't see it or go there but it "exists". There are even estimates of the distance to the edge.

"All the pieces add up to 78 billion-light-years. The light has not traveled that far, but 'the starting point of a photon reaching us today after travelling for 13.7 billion years is now 78 billion light-years away,' Cornish said. That would be the radius of the universe, and twice that -- 156 billion light-years -- is the diameter. That's based on a view going 90 percent of the way back in time, so it might be slightly larger."
http://www.space.com/scienceastronomy/mystery_monday_040524.html




3. Laypeople should not bash well-validated, though weird, theories based on their apparent absurdity.

They can't help it. The are not educated in science.


4. The views of the scientific community on global warming are NOT propagandized whether or not the danger is exaggerated or downplayed by politics. Astroid strikes are a risk, easily solvable with thruster packs, or, in a pinch, thermonuclear weapons in conjunction with an early warning system.

Yeah sure. We couldn't get a rocket put together to put something like that on an asteroid in under two to three years. We do have a warning system, it's called LINEAR. Look it up. The last close call was detected AFTER it passed between the Earth and Moon.


4. Dissent is an essential part of science, though unfortunately things can occasionally become dogmatic. However, our science is much more complete than it was, and many movements seem to me like a kind of denialism. I believe that global warming and depletion of resources pose a very severe danger to "homeworld security" but it is easily within our grasp to solve this problem through a great project that would generate hundreds of millions of jobs and possibly elevate the starving millions to a state of civilization.


Idealism belongs to the young, realism comes with maturity. We will never stop war or be able to prevent starvation. We are predators which is why we are at the top of the dung pile. Predators kill their food and their competition.

Fasttrack
07-19-2009, 07:32 PM
Idealism belongs to the young, realism comes with maturity. We will never stop war or be able to prevent starvation. We are predators which is why we are at the top of the dung pile. Predators kill their food and their competition.

:) I enjoyed that post very much. The cost for "civilization" is human suffering. For every good thing that I have, someone else is making a sacrafice so I can have it. Not every one gets to be on top - the best I can do is appreciate my position and do my best to ease the suffering of the less fortunate, imho.

I agree with TM that dissent is an essential part of science. However, I will admit I didn't read past that. I don't have an opinion on the problems of tomorrow. The problems of today are enough to worry about :D

aostling
07-19-2009, 09:21 PM
Something entirely obscure such as "Transport Phenomena by Bird, Stewart, Lightfoot" will get attention (It's on my shelf, all about heat flow. Make sure there is room beside you.


That book is heavy reading. Have you actually cracked it, hoping it might bring some shuteye at 3 AM?

I thought the hardest subject was compressible fluid flow. Does your shelf have a volume or two by Ascher Shapiro too?

Evan
07-19-2009, 09:42 PM
I have read of it here and there. It has information I have required from time to time for various projects. I find it interesting. Shapiro doesn't ring a bell.

Compressible fluid flow is an entirely different beast than low velocity air or liquids. There is a lot of nonlinearity to deal with. Have you ever done any studying of driven shock waves such as from explosives?

Evan
07-19-2009, 09:58 PM
I meant to add that I just gained ownership of a sturdy 30 foot galvanized steel tower in good shape. I am planning to do some experimentation with shock wave forming of metal. Explosives annoy the neighbours and I don't have enough high voltage capacitors to use spark but dropping 50 lbs of lead from 30 feet in a controlled manner will provide about 800 ft lbs energy to the target in a few milliseconds.

dp
07-19-2009, 10:08 PM
I agree with TM that dissent is an essential part of science. However, I will admit I didn't read past that. I don't have an opinion on the problems of tomorrow. The problems of today are enough to worry about :D

I get a giggle when a teen describes in grand prose how lay people should behave or think. There's just something pontificatious in that.

dp
07-19-2009, 10:15 PM
I meant to add that I just gained ownership of a sturdy 30 foot galvanized steel tower in good shape. I am planning to do some experimentation with shock wave forming of metal. Explosives annoy the neighbours and I don't have enough high voltage capacitors to use spark but dropping 50 lbs of lead from 30 feet in a controlled manner will provide about 800 ft lbs energy to the target in a few milliseconds.

Harley-Davidson uses that technique to form the frames of the V-Rod motorcycles. They had and possibly still have an interesting video of the process. The part has to be a pretty close fit to go into the forms but one ka-bang and it's a perfect fit. There must be a way to expel air from the form quickly to avoid being trapped.

aostling
07-19-2009, 10:39 PM
Compressible fluid flow is an entirely different beast than low velocity air or liquids. There is a lot of nonlinearity to deal with. Have you ever done any studying of driven shock waves such as from explosives?

I did an analysis of a detonation of a LOX tank. This was for an installation at MERDI in Butte, Montana, in 1978. A few years earlier there had been a LOX accident when an aluminum tank detonated, I think at a facility in Alabama or Tennessee. It was thought that a stress crack had brought the LOX into contact with metallic aluminum, which as you stated in an earlier post is very explosive. I'm not sure I buy into that scenario, but the detonation which did happen resulted in some fatalities. They wanted to know how big a berm to hide the tank behind to prevent this from happening in Butte. My analysis was rather simple, first law and thermodynamic state properties, to get a good estimate.

I spent most of my career doing analysis, mostly fluids and heat transfer. The two most lucrative specialties for contract mechanical engineering are stress, and thermal. I did the latter. In some ways it was a strange way to make a living, predicting temperatures in aircraft and spacecraft components, long before the vehicles existed. We thermals always felt superior to the stress analysts, who we thought just "turned the crank" on tedious software without really having to think about what they were doing. I usually managed to come up with temperature predictions by modeling no more than a few dozen "nodes." A node is any modeled entity assumed to have a uniform temperature and heat capacity, and since so much of aircraft is aluminum (with high thermal conductivity), it is often appropriate to lump lots of connected parts into a single node. But there are guesses involved, for contact conductance and convection heat transfer coefficients, which the stress analysts called our "agreed-upon lies."

Once the nodes and the connecting "conductors" are defined, it is easy to predict temperature transients with the SINDA software. This was developed by Chrysler in 1962 for the Apollo project, when it was called CINDA (Chrysler Improved Numerical Differencing Analyzer). It is still in use today.

Evan
07-19-2009, 11:23 PM
Once the nodes and the connecting "conductors" are defined, it is easy to predict temperature transients with the SINDA software. This was developed by Chrysler in 1962 for the Apollo project, when it was called CINDA (Chrysler Improved Numerical Differencing Analyzer). It is still in use today.

No doubt written in Fortran. Fortran is the BASIC of numerical analysis and has survived probably longer than any other high level language. BTW, the name is a contraction of Formula Translator.

Evan
07-19-2009, 11:35 PM
Dennis,

The trapped air problem is best dealt with by pulling a vacuum under the part. If that isn't possible perhaps because the part isn't strong enough then filling with helium works well. I have a small tank of pure helium which I plan to use for that purpose if I can find the time. What brought this to mind is your copper egg. It should be easy to form an egg in two halves using lead positives as "stretch over molds" cast from plaster negatives made from a real egg. I figure the force can be transmitted to the copper blank by fastening it to the bottom of a heavy wall tube partly filled with jello and a ram above that with a striking surface for the weight to fall on.

The essential part of explosive forming is that it be very fast. The metal flows instead of stretching and so can be made to assume shapes not possible by using an ordinary press. I was also thinking of boosting the power a little bit by using an ounce or so of black powder for the weight to set off by compression at it hits.

Fasttrack
07-19-2009, 11:47 PM
Fortran is just now begining to decline in popularity in the scientific community, especially in the HEP community. All the trigger software and nearly all of the analysis software in use (or about to be put into use) at CERN is based on C. It is much easier to handle vast amounts of data with C than with Fortran, but Fortran certainly kicks butt when it comes to number crunching!

andy_b
07-22-2009, 11:36 PM
I believe that global warming and depletion of resources pose a very severe danger to "homeworld security" but it is easily within our grasp to solve this problem through a great project that would generate hundreds of millions of jobs and possibly elevate the starving millions to a state of civilization.


yeah, if that "great project" is building the soylent green processing vats to feed those starving millions.

andy b.

tony ennis
07-23-2009, 12:47 AM
Fortran ... has survived probably longer than any other high level language.

COBOL is #1, methinks.

It's hard to think of a reason to use Fortran instead of C.

Evan
07-23-2009, 06:32 AM
Nope. FORTRAN was defined in 1957, COBOL in 1960.

sch
07-23-2009, 12:52 PM
Re explosive forming: There is a video probably from a Mil channel or that
ex seal guy basically showing how easy an IED is to make. Expert shows
a chunk of plastic sched 80 pipe about 4-6" ID with a glued on cap, about
3" deep. Packs cylinder full of plastique and puts a conical cap of copper
with the pointy part inward in the plastique. Covers with a second cap,
fuses with electric blast cap and points cylinder, copper end first toward
a 3' square plate ~0.5" or maybe 0.75" (max) thick about 20' away.
Bang and there is a 1" hole in the plate with blast pits around it from other
fragments. Scale it up and you can blow an Abrams.

camdigger
07-23-2009, 01:25 PM
Re explosive forming: There is a video probably from a Mil channel or that
ex seal guy basically showing how easy an IED is to make. Expert shows
a chunk of plastic sched 80 pipe about 4-6" ID with a glued on cap, about
3" deep. Packs cylinder full of plastique and puts a conical cap of copper
with the pointy part inward in the plastique. Covers with a second cap,
fuses with electric blast cap and points cylinder, copper end first toward
a 3' square plate ~0.5" or maybe 0.75" (max) thick about 20' away.
Bang and there is a 1" hole in the plate with blast pits around it from other
fragments. Scale it up and you can blow an Abrams.

What you're describing is a primitive shaped charge. The copper liner is converted to a plasma jet by the plastique that will burn through just about anything including steel, concrete, and rock. Shaped charges were originally only for demolition or armed conflict type applications, but have been applied to other things too. Most of the oil and gas wells completed in the last 40 years used shaped charges to perforate the steel casing cemented in place to establish a flow path from the payzone into the cased well bore.

Modern super deep penetrating charges can put a roughly 1/2" hole 39" deep into solid rock with a mere 25 grams of HDX or RDX. Different liner compostion and shape along with various loads of RDX or HDX give predictable and sometimes surprising performance. Performance sheets are available online from Owen, Innicor, Titan, etc.