Even diverting the entire present-day human energy consumption of ~1013 watts, already approaching the hypsithermal limit for Earth1, exclusively to nanotech gold extraction from crustal rock would produce only ~300 tons/yr of new gold. This won't seriously disrupt international gold prices, because world gold production already averages ~1500 tons/yr6 using 5,000-10,000 ppb ores, and because a total of ~100,000 tons of gold has been extracted throughout history7, most of it still extant, worth ~$1 trillion at today's prices. Perhaps you are thinking that it might make more sense to do a
little environmental remediation while reworking the mining industry
tailings, which are typically ~1,000 ppb gold6, and extracting
all of the remaining precious metal. Working on the richer tailings
rather than raw crustal rock, our nanotech desktop refinery could
produce ~300 troy ounces of pure gold per year, worth $100,000/yr
at current market prices. Unfortunately, the energy cost is still
$900,000/yr at today's $0.10/Kw-hr electric rates. If future energy
rates are a lot cheaper than today's rates, well and good. But note
that only ~108 tons of new mine tailings are piled up
annually, with each year's leavings containing ~100 tons of unextracted
gold. Even if completely extracted, all of the gold in these tailings
would still be far less than the total aboveground worldwide stockpile
of the metal. What about seawater extraction8? Gold is
~100 times less plentiful in seawater than in the crust, though
gross filtration and bulk preprocessing might improve throughput.
Other potentially inflationary imports into the world economy from
future extraterrestrial sources of monetary gold -- such as metal-rich
asteroids -- may be largely offset by relatively high prospecting
and shipping/insurance costs, and by a fast-growing economy able
to fully absorb a rapidly expanding money supply. The bottom line is that at ~$200/cm3, gold at least
minimally satisfies our eight criteria for an ideal tangible nanomoney.
Its rareness will not be decisively altered by nanotechnology. But
the "precious yellow" owes its historical preeminence
to the fact that gold is the most easily extractible inert rare
element in the Earth's crust. In the nanotech era, other alternatives
may exist. Antimatter
|
Table 2. The Rarest Natural Isotopes and
Their Current Prices11-13
|
Relative Isotopic Abundance
|
Terrestrail Crustal Rock Abundance
|
Actual or Estimated Current Prices
|
Notes
|
|
Tc97 (Note 1) |
-
|
~0
|
$30,000000000/gm
|
(est.)
|
Tc98 (Note 2) |
-
|
~0
|
$30,000000000/gm
|
(est.)
|
He3 |
(0.000137%)
|
0.000007535
|
$637.31/gm
|
|
Xe126 |
(0.090%)
|
0.000018
|
$28,948.49/gm
|
|
Xe124 |
(0.096%)
|
0.0000192
|
$15,483.24/gm
|
|
Os184 |
(0.018%)
|
0.000324
|
$30,000,000/gm
|
(est.)
|
Xe128 |
(1.92%)
|
0.000384
|
$7,000/gm
|
(est.)
|
Kr78 |
(0.35%)
|
0.000525
|
$6,923.26/gm
|
|
Xe130 |
(4.08%)
|
0.000816
|
$3,900/gm
|
(est.)
|
Te120 |
(0.089%)
|
0.00089
|
$1,400,000/gm
|
(est.)
|
Xe136 |
(8.87%)
|
0.001774
|
$2,156.21/gm
|
|
Xe134 |
(10.44%)
|
0.002088
|
$2,389.46/gm
|
(Note 3)
|
Kr80 |
(2.28%)
|
0.00342
|
$5,791.52/gm
|
|
Xe131 |
(21.18%)
|
0.004236
|
$1,658.94/gm
|
|
Pt190 |
(0.0127%)
|
0.00470
|
$1,347,960/gm
|
(Note 4)
|
Xe129 |
(26.44%)
|
0.005288
|
$691.31/gm
|
|
Xe132 |
(26.89%)
|
0.005378
|
$700/gm
|
(est.)
|
Te123 |
(0.89%)
|
0.0089
|
$140,000/gm
|
(est.)
|
Kr83 |
(11.49%)
|
0.017235
|
$2,600/gm
|
(est.)
|
Kr82 |
(11.58%)
|
0.01737
|
$2,580.90/gm
|
|
Ru98 |
(1.87%)
|
0.0187
|
$323,040/gm
|
|
Te122 |
(2.55%)
|
0.0255
|
$76,850/gm
|
|
Kr86 |
(17.30%)
|
0.02595
|
$196.51/gm
|
|
Os186 |
(1.59%)
|
0.02862
|
$600,500/gm
|
(Note 5)
|
Os187 |
(1.96%)
|
0.03528
|
$159,060/gm
|
(Note 6)
|
Te124 |
(4.74%)
|
0.0474
|
$29,230/gm
|
|
Ru96 |
(5.54%)
|
0.0554
|
$100,000/gm
|
(est.)
|
Pd102 |
(1.02%)
|
0.06426
|
$893,800/gm
|
(Note 7)
|
Te125 |
(7.07%)
|
0.0707
|
$16,040/gm
|
|
Kr84 |
(57.00%)
|
0.0855
|
$338.33/gm
|
|
Hg196 |
(0.146%)
|
0.09782
|
$3,141,500/gm
|
(Note 8)
|
Ru100 |
(12.60%)
|
0.1260
|
$43,170/gm
|
|
Ru99 |
(12.76%)
|
0.1276
|
$39,040/gm
|
|
Ir191 |
(37.3%)
|
0.1492
|
$12,070/gm
|
|
Ru101 |
(17.06%)
|
0.1706
|
$35,050/gm
|
|
Ru104 |
(18.62%)
|
0.1862
|
$27,300/gm
|
|
Te126 |
(18.84%)
|
0.1884
|
$8,950/gm
|
|
Ta180m |
(0.0123%)
|
0.2091
|
$17,095,890/gm
|
(Note 9)
|
U234 |
(0.0057%)
|
0.228
|
$61,800/gm
|
(Note 10)
|
Os188 |
(13.24%)
|
0.23832
|
$31,200/gm
|
|
Ir193 |
(62.7%)
|
0.2508
|
$6,070/gm
|
|
Pt192 |
(0.782%)
|
0.28934
|
$139,600/gm
|
(Note 11)
|
Os189 |
(16.15%)
|
0.2907
|
$25,260/gm
|
|
Ru102 |
(31.55%)
|
0.3155
|
$20,410/gm
|
|
Te128 |
(31.74%)
|
0.3174
|
$4,340/gm
|
|
Te130 |
(34.08%)
|
0.3408
|
$4,490/gm
|
|
Se74 |
(0.89%)
|
0.445
|
$761,190/gm
|
(Note 12)
|
Os190 |
(26.26%)
|
0.47268
|
$13,720/gm
|
|
Rh103 |
(100%)
|
0.70
|
$29/gm
|
|
Pd104 |
(11.14%)
|
0.70182
|
$63,800/gm
|
|
Os192 |
(40.78%)
|
0.73404
|
$10,400/gm
|
|
Pd110 |
(11.72%)
|
0.73836
|
$67,090/gm
|
|
Re185 |
(37.40%)
|
0.9724
|
$9,400/gm
|
|
Ag |
(nat. isot. mix)
|
80
|
$0.20/gm
|
|
Au |
3.1
|
$10/gm
|
||
Pt |
(nat. isot. mix)
|
37
|
$12/gm
|
|
Diamond |
(natural)
|
-
|
$28,000/gm
|
(Note 13)
|
- moderately radioactive, decays by gamma emission and electron capture to Mo97, t1/2 = 2.6 ×106 yr;
- moderately radioactive, decays by gamma and beta emission to Ru98, t1/2 = 4.2 ×106 yr;
- only 51% enrichment;
- only 4.19% enrichment of this slightly radioactive alpha emitter, t1/2 = 7 ×1011 yr;
- only 79.48% enrichment;
- only 70.43% enrichment;
- only 78.18% enrichment;
- only 31%-48% enrichment;
- only 5.70% enrichment, as oxide;
- moderately radioactive alpha emitter, t1/2 = 2.48 ×105 yr;
- only 41.63% enrichment of this slightly radioactive alpha emitter, t1/2 ~ 1015 yr;
- 77.71% enrichment;
- investment grade D flawless, cut gemstones, 1-carat size (1997 JCK market quotes).
Technetium (Tc) is present in the Earth's crust only as minute
traces from the spontaneous fission of natural uranium; the short
half-life precludes primordial technetium on Earth. The element
is also observed in the stellar atmospheres of S-, M-, and N-type
stars. Tc is artificially created on Earth by bombarding molybdenum
or rhodium targets with protons or deuterium nuclei, producing some
isotopes at a cost of ~$30 billion/gm14 (~$350 billion/cm3).
Alternatively, technetium-99 is a fission byproduct of nuclear reactors
and is harvested by the nuclear fuel reprocessing industry, a vastly
cheaper source which allows kilogram-quantity production of Tc99
at a cost of ~$100/gm15. Technetium is a silvery grey
metal that tarnishes slowly in moist air, density 11.5 gm/cm3,
melting point 2157ºC. It would require airtight encapsulation
in a shell of chemically inert metal such as gold or platinum. But
its use in specie is unlikely because the metal is moderately radioactive.
For example, even with a 2.6 million-year half-life, Tc97
emits ~30 microwatts/cm3 of decay energy or ~600 million
Bq/cm3 (~0.3 rad/sec), compared to a background count
of ~7000 Bq16 for the natural human body.
The rarest nonradioactive isotopes found naturally on Earth are
the three gaseous isotopes He3 (1 atom per 24 trillion
atoms in Earth's crust), Xe126 (1 atom per 370 trillion
crust atoms), and Xe124 (~1 atom per 350 trillion crust
atoms), all available commercially17. The precious metal
atoms gold, silver, and platinum are about 10 million times more
abundant.
Noble gas atoms may be encapsulated in fullerene cages such as
C6018, 19. One present-day encapsulation technique
involves heating bulk fullerenes to 650°C at 3000 atm gas pressure,
a procedure which entrains 1 of every 1000 fullerene molecules with
a single noble gas atom19. With proper chemical treatment,
a C60 molecule can also have a stable orifice of fixed
diameter opened up in its side, only allowing atoms smaller than
a certain size to enter90, 91; radioactive holmium atoms
trapped in C82 cages are already used in biodistribution
experiments92. If we can find a low-cost method of purifying
the gas-entrained cage molecules, or can devise a more efficient
production method that achieves closer to ~100% entrainment, then
closely-packed roughly spherical C60 molecules each of
volume ~0.70 nm3 with a volumetric packing factor of 68% would allow
~0.95 ×1021 noble gas atoms/cm3 to be
stably stored, equivalent to a net storage pressure of 30-40 atm.
This gives an effective storage density of 0.005 gm/cm3
for He3 (specie value $3/cm3 20)
but 0.20 gm/cm3 for Xe126 (specie value $5,800/cm3
21). Although very rare, He3 is paradoxically
a relatively cheap isotope because of the vast supply of helium
produced by the petroleum industry -- gas-well helium averages 1.5
×10-5 % He3 22.
If we could raise the storage pressure to 1000 atm (12.3 ×1021
He3 atoms/cm3 or 9.48 ×1021
Xe atoms/cm3) and pack these gas atoms into sturdy single-walled
carbon nanotubes (SWCTs), then storage density rises to ~0.061 gm/cm3
for He3 (specie value $39/cm3) and ~2.0 gm/cm3
for Xe126 (specie value $58,000/cm3). Note
that the Van der Waals gas equation governs at such high pressures1,
not the ideal gas law, so still greater compression permits little
improvement in packing density.
For comparison, the volumetric values of more traditional specie
are $2/cm3 for silver, $200/cm3 for gold,
$260/cm3 for platinum, and $100,000/cm3 for
late-20th-century investment-grade diamonds.
NMR (nuclear magnetic resonance) could be used to noninvasively
measure the quantity of fullerene-entrained He3 present
inside the cladding because He3 is an excellent spin-1/2
NMR nucleus with a high gyromagnetic ratio19 at a resonance
frequency of ~7618 MHz. Xe129 (spin 1/2, ~2781 MHz) and
Xe131 (spin 3/2, ~824 MHz) are also known to be NMR active12.
Gold cladding would be NMR active at ~175 MHz (Au197,
nuclear spin 3/2), the only natural isotope12. The most
abundant platinum isotope (Pt195, 33.832%) is also NMR
active with a nuclear spin of 1/2 and a resonance at ~2141 MHz,
but the other two most common natural platinum isotopes (Pt194
at 32.967% and Pt196 at 25.242%) would provide a completely
NMR-inactive cladding12. Diamond cladding with pure C12
crystal would also be NMR-inactive, but may be too brittle for practical
use in circulating coinage.
Helium is not known to form covalent compounds, but by 1999 ~80
covalent compounds had been produced with xenon bonded to fluorine
and oxygen23, one of which possibly might provide a slightly
higher effective storage density of rare-isotope atoms than the
compressed gas. Unfortunately, xenon compounds tend to be highly
toxic because of their strong oxidizing character23,
hence represent a health threat to users in the event of breach
of the cladding material. Pure He and Xe are biologically harmless
in trace quantities, though in larger quantities xenon gas has been
used as an experimental surgical anesthetic in humans for several
decades11, 24.
The rarest and possibly most expensive nonradioactive isotope found
naturally on Earth that is a solid at normal room temperature and
pressure is an isotope of osmium, Os184. Osmium25
is a lustrous bluish white metal that is extremely hard. After iridium,
it is the densest known element (22.61 gm/cm3) and has
the highest melting point (3033°C) of the platinum group metals.
Solid metal won't tarnish in air, but finely powdered or spongy
metal slowly oxidizes, giving off caustic osmium tetroxide. OsO4
is highly toxic and is a powerful oxidizing agent with a low vapor
pressure (e.g. boiling point is 130°C at 1 atm) -- air concentrations
as low as 100 nanograms/m3 can cause lung congestion,
skin or eye damage25. Since the tetroxide has a strong
odor, osmium particles that oxidized and volatized after being exposed
to ambient air following a breach of the inert cladding would be
immediately detectable. Still, the potential for toxicity is a distinct
drawback to its use in nanospecie.
Os
Another candidate for the most expensive nonradioactive solid natural
isotope -- and perhaps the ideal candidate for tangible nanomoney
-- is an isotope of tantalum, Ta180m. After He3
and Ca46, Ta180m is the third rarest naturally
occurring stable isotope on Earth on a relative abundance basis.
First discovered in 195427, tantalum-180m has long been
believed to be so rare because it is largely bypassed in the two
processes that produced most of the heavy elements found in the
ground here on Earth -- (1) the s-process (slow neutron capture
during stellar helium burning) and (2) the r-process (rapid neutron
capture during supernova explosions)27-30. Apparently
in 1999, the entire world's supply of Ta180m was only
6.7 milligrams30.
Interestingly, the naturally-occurring isotope is not in the ground
state but is a nuclear isomer at an excitation energy of 73 KeV
with a spin parity of Jp = 9-28. In the ground
state, Ta180 decays in 8.15 hours by electron-capture
(EC) to Hf180 and by beta-decay to W180. It was originally predicted
that Ta180m would exhibit similar decay routes, but the most recent
experimental search28 has found no evidence of radioactive
decay products distinguishable from background levels, establishing
a lower limit on the Ta180m half-life of > 3.0 ×1015
yr for EC and > 1.9 ×1015 yr for beta-decay
and raising the possibility that these atoms are completely stable.
Tantalum is a hard, greyish-silver, heavy (16.6 gm/cm3)
metal that can be drawn into a very fine wire (high ductility),
and has a high melting point (3017°C) exceeded only by osmium,
rhenium, and tungsten. The metal is completely immune to chemical
attack at temperatures below 150°C and above this temperature
is attacked only by hydrofluoric acid, acidic solutions containing
the fluoride ion, and free sulfur trioxide, and only very slowly
by alkalis. Coins minted of pure Ta180m extracted using
current bulk separation methods would have a value of at least $284
million/cm3, or even more because the value given in
Table 2 is for 5.7%-enriched metal only. Natural tantalum metal
and its stable pentoxide are biologically inert31-34,
so the metal is widely used in medical implants such as sutures,
cranial repair plates, and other prostheses. But Ta180m
coins might still be cladded with gold or platinum to forestall
a decline in their value due to wear abrasion. Coin purity can be
determined by bremsstrahlung irradiation photoactivation analysis
30 or by other means; a cheap cladding made of Ta181,
the most abundant natural isotope, would be NMR-active (spin 7/2,
~1199 MHz).
Couldn't we just buy some natural bulk pure tantalum (mostly Ta181),
currently costing $1.20/gm89, then use nanotech concentrators
to perform an isotopic separation to extract the 1 atom in every
81,300 that is a Ta180m atom? We could indeed! Neglecting
chemical pre- and post-processing expenses, a 0.02 M aqueous solution
of TaF5 fed into a 32-stage teragravity nanocentrifuge
cascade1 could have its Ta180m content enriched
from 0.0123% to 5.7% for an energy cost of ~$1,000/gm ($16,600/cm3),
assuming $0.10/Kw-hr.
But keep in mind that today's relatively cheap natural tantalum
is derived from concentrated tantalite ores, not from random crustal
rocks. The total quantity of Ta180m available in the
entire 1996 world reserve base of tantalum (including all known
economic, marginal, and even subeconomic reserves still in the ground)
was a mere 4,200 kg93. At $1,000/gm, our 4,200 kg of
metal is only worth $4.2 billion -- a spit in the bucket against
today's $20 trillion world money supply. Once the whole 4,200 kg
has been extracted and there is still demand, the metal price must
rise sharply or else new (but presumably poorer, harder to find)
ore deposits must be discovered. How high could the price go? Who
knows? But we do know that the world reserve base for gold in 1996
was 61,000,000 kg 93, and at ~$350/oz the market was
valuing this reserve base of monetary metal at ~$0.7 trillion. If
the world reserve base of Ta180m is assigned gold's monetary
function and is similarly valued at $0.7 trillion, and if vast new
tantalum ore deposits prove difficult to find, then the price of
Ta180m could rise to ~$170,000/gm ($2.8 million/cm3).
Note also that tantalum is more than 1000 times rarer than gold,
in seawater12.
Ta181 would be a convenient "base" substance
with which to dilute the Ta180m down to minute concentrations,
in order to make lower-denomination coins. Nanotech coin-verifying
machines could quickly clean and map the worn, scratched exterior
surface of a specimen coin to atomic resolution, then weigh the
specimen coin to single-proton mass accuracy1, allowing
the computation of the precise number of Ta180m atoms
present within the cladding on the assumption that Ta180m
is the only impurity in the Ta181 base metal. In theory,
a more detailed assay could be done, with the coin completely deconstructed,
counted and verified atom by atom, then reconstructed back into
the original form in a few minutes, perhaps using a verification
machine similar in size and speed to the desktop manufacturing appliance
mentioned earlier.
Can we breed new Ta180m atoms more cheaply by artificial
means, avoiding the costly enrichment process from limited and dilute
natural sources? Maybe, maybe not. Five nucleosynthetic techniques
have been proposed for making Ta180m 29, 30.
Two seem to require Type II supernova conditions, and another is
now believed not to work. The other two methods involve a rare s-process
neutron capture synthesis. One of these is at most ~0.01% efficient29.
The other method requires nuclear precursors to be held near 300,000,000
degrees K to induce transformation, but at this temperature the
normally stable Ta180m has a half-life of only 130,000
sec30. Additionally, the high-nuclear-energy Ta180m
isomer thus produced then decays into the stable Ta180m
isomer with only 3.8% probability, so this method also appears very
inefficient. A 0.01% production efficiency, requiring ~10,000 26-KeV
neutrons per atom of Ta180m synthesized, would imply
a minimum energy cost of $40,000/gm (~$600,000/cm3) to
manufacture stable Ta180m, assuming the current $0.10/Kw-hr
electric rate. The apparent difficulty of making this isotope may
be a fundamental physical limitation which the future advent of
nanotechnology is not likely to substantially alter.
One drawback to any natural material is that a plentiful natural
source might conceivably be found someday, devaluing the currency
and triggering rampant inflation. Ideally, we'd prefer a substance
for which no natural sources are available or likely, and which
is intrinsically very difficult to produce artificially. This leads
us to the superheavy elements or SHEs70-74.
The number of elements is limited because nuclei become increasingly
unstable against spontaneous fission and alpha-decay as proton number
increases. For example, between thorium and the heavy fermium isotopes,
the spontaneous fission half-life plunges by 30 orders of magnitude76.
But in 1948, Goeppert-Mayer35 pointed out that nuclear
shell closure effects would substantially increase nuclear stability,
and Wheeler36 in 1955 and Scharff-Goldhaber in 195737
postulated the existence of transactinide elements with atomic numbers
above 103, the SHEs. By equating Coulombic and surface energy of
the nucleus, Huizenga38 had argued that the maximum number
of chemical elements should be ~125, but in 1990 Seaborg estimated
that more than 500 undiscovered transuranic isotopes might exist73,
and in 1996 Seaborg reproduced a "Futuristic Periodic Table"
with atomic numbers running as high as hypothetical element 16839
similar to other hypothetical tables published decades earlier40,
62. There have been speculations on the possible chemical
properties of elements with atomic numbers up to 18461, 64
and on the nuclear stability of elements with atomic numbers up
to 27441.
Starting in the 1960s and 1970s, theoretical research on the SHEs
largely centered on a hypothesized nuclear "island of stability"
centered on element 114298 42-48, with half-life
predictions ranging from a few months49 for 114310,
5 years74 for 118302, 1000 years41
for 112296, and 1079 years74 for 116300,
up to as high as 0.1 million years41, 50, 20 million
years51, 1 billion years 41, or 2.5 billion
years52 for 110294. The stabilization near
114298 is due to the complete filling of nuclear proton
and neutron shells, analogous to the complete filling of electronic
shells in the noble gases in chemistry. Another "island of
stability" was predicted to exist around element 164472
by Sobiczewski et al53, with half-lives ranging from
105-107 years. Taking spontaneous fission,
alpha and beta decay, proton emission and electron-capture decay
modes simultaneously into account, others have estimated more pessimistic
half-lives74-78. On the other hand, if certain unconventional
assumptions are made about nuclear shapes and deformations54,
some elements with atomic numbers above 134 might be stable.
The possibility of very long-lived SHEs triggered a major hunt
for these atoms in nature. Searches of various ores and minerals,
meteorites and hot brines, leaded glass, cosmic rays, and even lunar
samples for evidence of SHEs came up empty45, 74. Flerov
and Ter-Akopian45 report negative detection limits as
low as 10-14 - 10-17 gm/gm. Thus any natural
SHEs that might be present must be 1-1000 times rarer than He3
atoms and 0.01-10 million times rarer than Ta180m atoms.
Current thinking is that it is unlikely that the r-process (rapid
neutron capture in supernovae, >~1027 neutrons/cm2-sec
for 1-100 sec55) of heavy element nucleosynthesis will
lead to the production of SHE nuclei56, 73. (Nuclear
explosions typically produce neutron fluxes of >~1031
neutrons/cm2-sec for ~10-6 sec55, 57;
light-water nuclear reactors generate 2-5 ×1015
neutrons/cm2-sec for > 107 sec73.)
However unlikely, the possible existence of SHEs in nature cannot
yet be positively excluded58. For instance, a black hole/neutron
star binary system might provide an appropriate mechanism59.
The chemical nature of hypothetical SHEs has been extensively investigated60-70
although the theory is complicated by the need to include relativistic
effects70 -- e.g., for atomic numbers greater than 90,
orbital electron velocities exceed 50% of the speed of light73.
Pitzer63 concluded that elements 112 ("eka-mercury")
and 114 ("eka-lead") might be slightly metallic gases
or volatile liquids near room temperature, and element 118 ("eka-radon")
should also be a gas or volatile liquid. Fricke 64 agreed
that element 112 should be "a distinctly noble metal"
in macroscopic quantities with a density of 16.8 gm/cm3,
but "the interatomic attraction in the metallic state will
be small, possibly leading to high volatility as in the noble gases."
Hulet79 predicted that element 112 will boil at or below
room temperature. Keller et al60 estimated a melting
point for element 113 ("eka-thallium") of 430°C and
a density of 16 gm/cm3. For element 114, Keller et al60
estimated a melting point of 67°C, a boiling point of 147°C,
and a density of 14 gm/cm3. Element 114 is likely to be very chemically
inert64, 69. (Note again that gaseous or liquid atoms
can be entrained in fullerene cages, and thereby embodied in useful
specie.) Fricke64 estimated a density of 13.5 gm/cm3
and a melting point of 400°C for element 115. Stable element
164, if it exists, might have the highest density of any element,
~46 gm/cm3 64.
During the 1970s and 1980s, SHE element 106 was produced from O18
+ Cf249 with a cross section of 0.3 nanobarns81
and element 108 was made from the Fe58 + Pb208
reaction at 0.02 nanobarns82. In the 1990s, efforts to
create SHEs met with increasing success. For example, by 1999 four
isotopes of the famed element 114 (eka-lead or "ununquadium"
(symbol "UUQ"), the provisional IUPAC designation) had
been created artificially83-86, including 114285
(t1/2 = 0.6 millisec), 114287 (t1/2
~ 5 sec), 114288 (t1/2 < 0.03 sec), and
114289 (t1/2 = 30.4 sec). In Oganessian's
group85, 114289 was produced by bombarding
a Pu244 target with a 236-MeV Ca48 beam of
intensity 4 ×1012 ions/sec, making just one atom
of the SHE with a cross-section of ~1 picobarn -- out of 5.2 x 1018
incident calcium ions over a 34-day period, only one fusion event
corresponded to a compound nucleus that survived to give a Z = 114
nucleus48. By late 1999, elements 110277,
112281, 116289, and 118293 had
also been synthesized84.
Even if stable, long-lived SHEs can be artificially manufactured,
they are likely to remain extremely rare. There is a rapid decrease
in the production cross section, with increasing nuclear charge,
typically <~1 nanobarn for elements above 10579, 80.
For example, Wolf et al87 predicted the peak cross-section
for making element 106 from the Es253 + Xe136
deep inelastic transfer reaction to be 10 nanobarns, but only ~1
picobarn for producing element 110 and ~0.1 picobarn for making
114290 in the same reaction. Nitschke88 estimated
the cross-section to produce element 114 from the U238
+ U238 reaction as ~0.1 nanobarns, and from a variety
of other reactions as from 0.00002-20,000 picobarns. Production
rates of SHEs are on the order 1 atom/hour or less70
and Coulomb barrier energies are on the order of 200-300 MeV79.
Seaborg and Loveland73 note that the predicted cross-sections
for heaviest element formation by heavy ion bombardment are less
than 10-8 of the total reaction cross section, "corresponding
to the production of less than 1 atom per day of irradiation"
using incident beam particle fluxes of 1013-1015
ions/sec from modern accelerators.
We see that stable superheavy atoms could be perhaps a trillion
times more costly to manufacture than artificial Ta180m,
suggesting a very speculative value of ~$0.001/atom (~$2 ×1018/gm)
using our customary electric rate assumptions. Even if the material
was slightly radioactive, very few SHE atoms would be required to
impart great value to the specie, substantially eliminating the
radiation risk. For example, a coin with $1 million face value need
contain only 109 SHE atoms worth $0.001/atom. Assuming
a 106-year half life, there are only ~2 disintegrations
per day, well below the background count from today's circulating
base-metal coins (~3-30 counts/day, per gram). Our million-dollar
coin would lose only ~$0.50/yr (~$500/millennium) of intrinsic value
due to radioactive decay.
Aside from the radioactivity, any biotoxicity of SHEs is unlikely to be of much importance since the concentration of SHE would be so low and because the bulk of the coin would consist primarily of "cheap" bioinert material such as gold, platinum (failure strength ~100 times greater than gold), or diamond. Such coins, perhaps containing trace amounts of ununquadium or some other relatively stable SHE, might prove to be the ultimate tangible nanomoney.
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[Post New Comment]
Mind·X Discussion About This Article:
Future of Physical Money |
[Top] [Mind·X] [Reply to this post] |
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This article is certainly a change from RF's other work on nanomedicine, quite intriguing, too! I tend towards the view that cultures and social groupings may well choose their own forms of coinage et al, but the matter of counterfeiting is well-raised. For those who eschew technology, the question of making a money supply trustworthy seems difficult to resolve to any degree of success. And I recall from Ray Kurzweil's last book that he fully anticipates nanotechnology to be superseded in a few decades after its arrival by picotechnology, and thence onwards (and downwards!) to femtotechnology and presumably attoechnology and so forth. I wonder if his new bok will explore that notion, in the event he still holds to it. If so, it might give the matters posed in this article a use-by date! One possibility is the creation of artificial atoms, which I recall reading in Wired a little while ago. It may turn out that especially sophisticated and naturally non-occuring atomic structures could offer a means to constructing a safe money supply, when the means become available and nanotechnology is superseded. As the pace of technology becomes more advanced, the designs for the coinage's matter could be upgraded to something far harder to replicate. In which case, the compute-cycles involved in the money's design and construction may well be reflected in the value of the coin itself. I wonder what the rest of the visitors here think! |
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Re: Future of Physical Money |
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I think at some point we won't use money anymore. |
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Re: Future of Physical Money |
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I only use it for about 10% of my purchases already. My ATM card buys most of what I need and the government fills my bank account every month with the credit to back it up. The only thing I use money for is purchases from small businesses that only take cash. The money I keep in my wallet for emergencies seems to last forever. |
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Re: Future of Physical Money |
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Actually, I meant that you won't need a credit card either, because the cost of everything will tend toward zero.
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Re: Future of Physical Money |
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It's likely that VR will become popular, but it's also likely that people will still take trips.
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Errrrr . . . |
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Ok, I will first confess my general ignorance in the more hard-science ends of this. But, my general educational background and interests in the general fields allow me to at least comment on this. In essence, while reading through this and similar articles, it seems to me that this is the wrong question to be asking entirely.
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Re: Errrrr . . . |
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GAJ
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