Modern Warfare in the 20th Century

The development of weapons researchThe development of weapons laboratoriesThe emergence of modern science

World War I Trenches

Marne 1914Ypres 1915

Verdun 1916Somme 1916

Cambrai 1917

Tanks

New Weapon Technologies

A British army officer, Colonel Ernest Swinton and the Secretary

of the Committee for Imperial Defense, Maurice Hankey, were

enthusiastic about the development of a new “armored caterpillar” (landship) for breaking through enemy trench defenses. It was Churchill who sponsored the

establishment of the Landships Committee to investigate the potential of constructing what

amounted to a new kind ofmilitary weapon in the 20th century.

Tanks to get the battles moving

First used by Britisharmy at the Somme; initial surprise but

attack stalled

First major British tank attack at battle

of Cambrai with more than 400 tanks!

New Weapons at Air

Rapid development of air force leading from observation purpose toplane to plane air battle to bomb raid techniques.First restricted to raidson enemy combatantsbut rapidly used for airraids on industry, towns,villages, and civilianspaving the way for theair raid techniques inWorld War II and after.

The Development of Chemical Weapons

1915 tear gas1915 Chlorgas1916 Phosgen1916 Senfgas1916 Grünkreuz1917 Blaukreuz1917 Gelbkreuz

125,000 tons of gas1 Million dead

Violation of Hague agreementfrom 1899 against the use of chemical weapons. Allnations signed except forthe United States!

Gas War

1st use of gas in 1915 at the second battle of Ypres

1906: Professor for Physical-ChemistryUniversity Karlsruhe

1911: Director , Kaiser Wilhelm Institutefor Physical-Chemistry, Berlin

1919: Nobel Prize in Chemistry For development of Haber Bosch method(extracting atmospheric Nitrogen and converting it to Ammonia)

1933: Resignation from his post asKWI director and emigrationto Cambridge, UK; died 1934.

Fritz Haber1868-1934

During the war Haber threw his energies and those of his institute into support for the German army. He developed a new weapon—poison gas, he supervised its initial deployment on the Western Front at Ypres, Belgium, in 1915.

Background Information

In 1981 as a young undergraduateHaber presumably synthesized first3,4-methylenedioxy-methamphetamine(MDMA, called now "Ecstasy")

3,4-methylenedioxy-methamphetamine

Clara Immerwahr-Haberwas the first women who attained a PdD in Chemistry (Breslau, 1900). She believed that science should be used for constructive purposes, not for weapons of mass destruction. Fritz Haber tried to keep Clara in the dark about his work on poison gas. During the night after the Gas attack in Ypres with ~5000 dead and ~2000 blinded she committed suicide.

The Kaiser Wilhelm Institutefor Physical Chemistry, Berlin

From applied research to war research

The beginning of a modern dayweapon laboratory, volunteeredfor weapon research in 1914 withthe start of WW-I, 25 years laterit was ordered to weapon researchin 1939 with the begin of WW-II.

The Great War generated a new mind set for the 20th Century

NA400,000325,000Turkey2,200,0003,620,0001,200,000Austria- Hungary

618,0004,247,0001,808,000Germany4.500206,000115,000United States

530,000947.000460,000Italy2,500.0004,950,0001,700,000Russia

446,0003,044,0001,385,000France192,0002,122,000947,000Great Britain

PrisonerWoundedDeadCountry

The Development of Nuclear Science

From 1900 - 1939

The Development of Scientific Thought in the 20th Century

Discovery & study of radioactivity 1898 Marie &.Pierre CurieIntroduction of quantum concept 1900 Max Planck hTheory of special relativity 1905 Albert Einstein E=m·c2

Quantization of light (photoelectric effect) 1905 Albert Einstein E=h·ν

Discovery of atomic nucleus 1911 Ernest Rutherford Interpretation of atom structure 1913 Nils Bohr

Particle waves 1924 Louis de BroglieWave mechanics 1925 Erwin SchrödingerUncertainty principle 1927 Werner Heisenberg

Discovery of Neutron 1932 James ChadwickArtificial Radioactivity (Reactions) 1934 Frederic Joliot & Irene CurieDiscovery of fission 1938 Otto Hahn, Fritz StrassmannInterpretation of fission 1938 Liese Meitner, Otto FrischPrediction of thermonuclear fusion 1939 C.F. v. Weizsäcker, H. Bethe

∆x·∆p=ђ

The new radiating material

Radioactive material such as Uranium- first discovered by Henri Becquerel –was studied extensively by Marie andPierre Curie. They discovered othernatural radioactive elements such as Radium and Polonium.

Nobel Prize 1903 and 1911!Unit of radioactivity:

The activity of 1g Ra=1Ci=3.7·1010 decays/s

Discovery triggered a unbounded enthusiasm and led to a large number of medical and industrial applications

Applications for radioactive

elements

Explanation of natural radioactivity

Ernest Rutherford's picture of transmutation. A radium atom emits an alpha particle,turning into “Emanation” (in fact the gas radon). This atom in turn emits a particle to become “Radium A” (now known to be a form of polonium). The chain eventually ends with stable lead. Philosophical Transactions of the Royal Society of London, 1905.

Radioactivity comes in three forms α, β, γ

Nobel Prize 1908

The radioactive decay law

( )t

t

eBtA

eBtB⋅−

⋅−

−⋅=

⋅=λ

λ

1)(

)(

0

0

λ≡decay constant;a natural constant for each radioactiveelement.Half life: t1/2 = ln2/λ

Activity A of radioactive material is proportional to its amount N

teNtN ⋅−⋅= λ0)(

Example: Radioactive DecayPlutonium 239Pu, has a half life of 24,360 years.1. What is the decay constant?2. How much of 1kg 239Pu is left after 100 years?

kgyN

kgyN

kgyN

kgyN

kgyN

ekgyNeNtN

yyt

Pu

Pu

Pu

Pu

Pu

yyPu

tPu

0578.0)000,100(

5.0)360,24(

7520.0)000,10(

9719.0)000,1(

9972.0)100(

1)100()(

1085.224360

2ln2ln

239

239

239

239

239

15

2392391001085.2

0

15

2/1

=

=

=

=

=

⋅=⇒⋅=

⋅===

⋅⋅−⋅−

−−

−−λ

λ

The first step: E=m·c2"It followed from the special theory of relativity that mass and energy are both but different manifestations of the same thing - a somewhat unfamiliar conception for the average mind. Furthermore, the equation E is equal to m c-squared, in which energy is put equal to mass, multiplied by the square of the velocity of light, showed that very small amounts of mass may be converted into a very large amount of energy and vice versa. The mass and energy were in fact equivalent, according to the formula mentioned before. This was demonstratedby Cockcroft and Walton in 1932, experimentally."

Nobel Prize 1921

Albert Einstein

Example: Mass-Energy

smc

smkgJmcE 8

22 10311 ⋅=

==

1kg of matter corresponds to an energy of:

( ) JsmkgsmkgE 16

21628 1091091031 ⋅=

⋅=⋅⋅=

Definition: 1 ton of TNT = 4.184 x 109 joule (J).

1 kg (2.2 lb) of matter converted completely into energy would be equivalent to the energy released by exploding 22 megatons of TNT.

By 1932 nucleus was thought to consist of protons and electrons which were emitted in β-decay. NewChadwick’s experiment revealed a third particle, the neutron

The discovery of the neutron

Nobel Prize 1935

Strong Polonium source emitted α particles which bombarded Be;radiation was emitted which – based on energy and momentumtransfer arguments - could only be neutral particles with similar mass as protons ⇒ neutrons: BEGIN OF NUCLEAR PHYSICS!

011 H

011 H

The model of the nucleus

Nucleus with Z protons (p) and N neutrons (n) with a total mass number A=Z+N

Hydrogen: 1 p, 0,1 n

Helium: 2 p, 1,2 n

Lithium: 3 p, 3,4 n

Carbon: 6 p, 6,7 n……

Uranium: 92 p, 143,146 n

242 He

011 H

6126C

363 Li

7136C

14623892U

121 D

132 He

473 Li

14323592U

N

ZModern Picturenuclide chart

Z=8, Oisotopes

A=20isobars

N=12 isotones

hydrogen isotopes: Z=1Isotopes: Z=constant, N varies!Isotones: N=constant, Z varies!Isobars: A=constant, Z,N varies!

Energy in NucleiAccording to Einstein’s formula each nucleus with certain mass m stores energy E=mc2

Proton mp = 1.007596 · 1.66·10-24 g = 1.672·10-24 gNeutron mn = 1.008486 · 1.66·10-24 g = 1.674·10-24 gCarbon m12C = 12.00000 · 1.66·10-24 g = 1.992·10-23 gUranium m238U= 238.050783 · 1.66·10-24 g = 3.952·10-22 g

B = (Z · mp+ N · mn- M) · c2

B(12C) = 1.47 · 10-11 J; B/A=1.23 · 10-12 JB(238U) = 2.64 · 10-10 J; B/A=1.21 · 10-12 J

Binding energy B of nucleus

Breaking up nuclei into their constituents requires energy

1 amu=1/12(M12C)=1.66 · 10-24 g

Nuclear Binding EnergyB

/A

in u

nits

MeV

A

1 MeV = 1.602·10-13 J

Binding energy normalized to mass number B/A

Example: Nuclear Binding EnergyConversion of nuclei through fusion or fission leads to release of energy!

( )

JJJQ

UBPdBPdBQ

QPdU

JJJQHBHBHeBQ

QHeHH

111010146

2389273

1194673

11946

7311946146

23892

121213

2242

421

211

21

1006542.31059633.121088631.2

)()()(

2

108647.31053295.41034131.32)()(2)(

−−−

−−−

⋅=⋅⋅−⋅=

−+=

+⇒

⋅=⋅−⋅⋅=

+⋅−=

+⇒+

2.88631·10-10238U1.59643·10-10119Pd1.47643·10-1112C4.53297·10-124He3.34131·10-132H

B (J)isotope

http://ie.lbl.gov/toimass.htmlhttp://nucleardata.nuclear.lu.se/database/masses/

Nuclear Energy possible through fission and fusion

In January 1933 Hitler was appointed byPresident Hindenburg asnew German Chancellor

Democratic partiesRight wing partiesLeft wing parties

-Reichstagsbrand-27 February 1933

This Decree of the Reich President for the Protection of the People and State abrogates the following constitutional protections: • Free expression of opinion • Freedom of the press • Right of assembly and association • Right to privacy of postal communications • Protection against unlawful searches & seizures • Individual property rights • States' right of self-government

A supplemental decree creates the SA (Storm Troops) and SS (Special Security) Federal police agencies.

The Reichstag building, seat of the German parliament, burns after being set on fire. This enabled Adolf Hitler to seize power under the pretext of protectingthe nation from threats to its security. (Photo credit: U.S. National Archives)

Consequences for Science and Academia

Removal from all Jewish faculty members from their posts(Law of restoration of Career Civil Service 1933).Many of the leading figures emigrated. Bernhard Rust becameMinister of Education tookMore flexible stand. Jewishscientists were allowed to holdtemporary assistant postsBut were facing increasing administrative difficulties.

KWI under Planck tried firstto remain independent butgot more involved in war relatedresearch during WW-II.

KWI for Physics in Berlin with van de Graaff Accelerator tower in front

Nuclear Reactions and Energy Release

Nobel Prize 1938

Frederic Joliot and Irene Curie at Paris had observed the first nuclear reaction. Enrico Fermi showed the existence of neutron induced reactions which produce artificial radioactivity.Nuclear reactions can produce energyQ > 0 exothermicor need energy Q < 0 endothermic

aA(a,b)B Q = (mA+ ma- mB- mb)·c2

Q = BB+ Bb- BA-BB

A

The discovery of fission 1938Search for transuranium elements Z>92238U (n, γ) 239U92 (β-) 239E93 (β-) 239E94

Hahn and Strassmann identified broad variety of elements, they thought those to be near Uranium, e.g. Z=88 Radium

Nobel Prize 1944

The interpretation of fission IHahn and Strassmann repeated the experiment numerous times and were never able to isolate the ‘radium’ from barium. They reported their results as follows: "As chemists, we must actually say the new particles do not behave like radium but, in fact, like barium; as nuclear physicists, we cannot make this conclusion, which is in conflict with all experience in nuclear physics." Hahn, the chemist, was reluctant to go against the ideas of nuclear physicists, despite clear chemical evidence of barium.

Close correspondence with collaborator Lise Meitner who had emigrated to Stockholm in 1938 to Manne Siegbahn.

The Interpretation of Fission IINow whenever mass disappears energy is created, according to Einstein's formula E = mc2, and... the mass was just equivalent to 200 MeV; it all fitted!Meitner was convinced that the product actually was Barium rather than a homologue. The nightmare of contradictory evidence all fit the explanationthat Uranium had fissioned (broke into pieces) rather than form a heavier element. Frisch calculated the energy needed, and Meitner calculated the energy available. The other fragment must be Krypton to conserve atomic number. 10n + 238

92U -> 137?56Ba + 84?

36Kr + 18? 10n

Niels BohrBrought news of fission to the US at the fifth Washington Conference on Theoretical Physics.Several researchers went back to their labs and confirmed the work and reported back before the conference was over.

Within a few month Bohr and Wheeler predicted the possibility ofchain reaction by fission of 235U with similar energy out put as 238U.Problem was to generate 235U, which is a very rare Uranium isotope.

Germany stopped all Uranium exports

Chain Reaction (?)

⇒ Chain reaction

10n + 235

92U → 14256Ba + 91

36Kr + 3 10n

The following is an example of a predicted fission reactions which generates neutrons besides energy.

The two fission products are very radioactive as they have far too many neutrons in their nuclei. Theneutrons are ejected and will then trigger subsequent fission processes

1939 Begin of World War II• Japan Invades

China

Hitler Invades PolandFrance

Belgium NetherlandsNorway DanmarkYugoslavia Greece

Concept of Strategic Air Bombing introduced by Sir Hugh Trenchard

World War II Weapons of Mass Destruction

W W II (1939-1945)

1940-41: Battle for BritainCivilian population targeted

1941-1944: Allied Bombing Campaign:Incendiary bombsCarpet bombingArtificial firestorms

~1000 planes/ severaltons of bombs eachSir Arthur Harris

(Bomber Harris)

Bombing Technique Developments

British and US air raids against Germany killed approximately 300,000 civilians and seriously injured about 780,000 more.

German air raids against Britain killed approximately 60,000 civilians and seriously injured about 80,000 more.

Large 500-1000 plane bombing armadas (limited defense)As well as area bombing techniques and firestorm techniques

Technological Escalation in WW II

Technological escalation during World War II was more profoundthan any other period in human history. More new inventions, certainlyas measured by such means as patent applications for dual-use

technology and weapon contracts issued to private contractors, were deployed to the task of killing humans more effectively, and to a much lesser degree, avoiding being killed. Unlike technological escalation during World War II, it was generally believed that speed and firepower, not defenses or entrenchments, would bring the war to a quicker end.