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#31
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"Pioneer anomalous acceleration" and Cassini
"Asimov" schrieb im Newsbeitrag ... If there was a recoil then a source such as an electron would be losing or gaining mass simply by a change in temperature. This hasn't been reported yet. Do electrons have a temperature? I thought they only have a speed. Lots of Greetings! Volker |
#32
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"Pioneer anomalous acceleration" and Cassini
"Asimov" wrote in message ... "Jim Greenfield" bravely wrote to "All" (05 Nov 03 21:28:55) --- on the heady topic of " "Pioneer anomalous acceleration" and Cassini" JG From: (Jim Greenfield) JG Subject: "Pioneer anomalous acceleration" and Cassini JG Organization: http://groups.google.com JG Xref: aeinews sci.astro:7536 JG "Asimov" wrote in JG message . .. "Jim JG Greenfield" bravely wrote to "All" (04 Nov 03 23:57:09) --- on the JG heady topic of " "Pioneer anomalous acceleration" and Cassini" JG From: (Jim Greenfield) The question was settled years ago. There *is* definitive anomalous acceleration in pioneer and the voyagers. No theoretical explanation has yet been settled on. JG Finally gathered the courage to tentatively suggest that when photons JG are emmitted, they give a 'recoil' against the source. If radiation JG from within the craft is directed in a particular direction, a thrust JG might occur. (I thought that this would be so insignificant as to be JG immesurable and undetectable, but maybe not) JG What would happen to a high-power laser carefully suspended- any JG chance of detecting an observable thrust counter to beam direction??? Saying a photon is "emitted" is a bit of a misnomer. I'd rather say a photon is released or let go. The momentum recoil is in the photon. That momentum is what results in radiation pressure on the receiving end. A photon is not so much emitted as the rest of the universe leaves it behind in time since after all the photon sees zero time elapsed. Anyways for whatever it's worth, photons interact with spacetime and in a sense it is spacetime that moves not the photon. The photon is just a little bit of history or information left behind and telling what the universe was doing at that instant. JG I am not interested in the photon after it leaves its source, but in JG its EFFECT on that source- as in the recoil of my rifle against my JG shoulder. JG George and Lupus seem to think there is a counter-push on the source JG caused by beam emmission, but you claim all energy is retained in the JG photon (correct?) If there was a recoil then a source such as an electron would be losing or gaining mass simply by a change in temperature. This hasn't been reported yet. |
#33
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"Pioneer anomalous acceleration" and Cassini
"Asimov" wrote in message ... "Jim Greenfield" bravely wrote to "All" (05 Nov 03 21:28:55) JG George and Lupus seem to think there is a counter-push on the source JG caused by beam emmission, but you claim all energy is retained in the JG photon (correct?) If there was a recoil then a source such as an electron would be losing or gaining mass simply by a change in temperature. This hasn't been reported yet. I have no idea what you mean. I suggest you look at Compton scattering regarding electrons. There is a recoil because momentum is conserved. The energy of a photon is E=hv and the momentum is p=E/c so the same momentum must be imparted to the emitting object but in the opposite direction. Force F=dp/dt and power P is dE/dt so F=P/c. For Pioneer the power is 8W so the force is 2.67*10^-8 N. The mass is about 240kg so the acceleration is 1.10*10^-10 m/s^2 or 1.10*10^-8 cm/s^2 as you will find it stated in Table II in the paper by Anderson et al, or see eqn (33) in section VIII, A. http://www.arxiv.org/abs/gr-qc/0104064 George |
#34
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"Pioneer anomalous acceleration"
"kurtan" wrote in message news:T7Lpb.851$%W3.1296@amstwist00... Perhaps some of you clever guys could care to bestow an opinion on findings at www.estfound.org/pioneer.htm . Is it go again for "Tired Light" redshift? No. If the craft was at a fixed distance, the shift from Tired Light would be constant. Doppler gives a constant shift for constant velocity. What is measured is an apparent acceleration hence it is the rate of change of the frequency shift. Since the shift depends on distance, the rate of change of the shift must depend on the speed of the craft. That speed doesn't even appear in their equations. In fact the shift produced by Tired Light is about four orders of magnitude less than the Pioneer anomaly. George |
#35
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"Pioneer anomalous acceleration" and Cassini
"George Dishman" wrote in message ...
"Asimov" wrote in message ... "Jim Greenfield" bravely wrote to "All" (05 Nov 03 21:28:55) JG George and Lupus seem to think there is a counter-push on the source JG caused by beam emmission, but you claim all energy is retained in the JG photon (correct?) If there was a recoil then a source such as an electron would be losing or gaining mass simply by a change in temperature. This hasn't been reported yet. I have no idea what you mean. I suggest you look at Compton scattering regarding electrons. There is a recoil because momentum is conserved. The energy of a photon is E=hv and the momentum is p=E/c so the same momentum must be imparted to the emitting object but in the opposite direction. Force F=dp/dt and power P is dE/dt so F=P/c. For Pioneer the power is 8W so the force is 2.67*10^-8 N. The mass is about 240kg so the acceleration is 1.10*10^-10 m/s^2 or 1.10*10^-8 cm/s^2 as you will find it stated in Table II in the paper by Anderson et al, or see eqn (33) in section VIII, A. http://www.arxiv.org/abs/gr-qc/0104064 Thanks George. I find the idea of the transfer of matter from atom - electron - photon - "somewhere in the universe" an interesting issue. Now can I have a set of scales sensitive enough to measure the weight difference as a (sealed) battery runs down? Jim G |
#36
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"Pioneer anomalous acceleration" and Cassini
"Jim Greenfield" wrote in message om... "George Dishman" wrote in message ... There is a recoil because momentum is conserved. The energy of a photon is E=hv and the momentum is p=E/c so the same momentum must be imparted to the emitting object but in the opposite direction. Force F=dp/dt and power P is dE/dt so F=P/c. For Pioneer the power is 8W so the force is 2.67*10^-8 N. The mass is about 240kg so the acceleration is 1.10*10^-10 m/s^2 or 1.10*10^-8 cm/s^2 as you will find it stated in Table II in the paper by Anderson et al, or see eqn (33) in section VIII, A. http://www.arxiv.org/abs/gr-qc/0104064 Thanks George. OK, if you have any lingering doubts, just remember: solar sails work ;-) I find the idea of the transfer of matter from atom - electron - photon - "somewhere in the universe" an interesting issue. If we get into SR, it will make the relationship between energy and mass clearer, and move you on to the next set of interesting questions ;-) Now can I have a set of scales sensitive enough to measure the weight difference as a (sealed) battery runs down? That might be tricky, but the Sun loses about 4 million tons per second this way. We still can't measure it though, but we can measure the difference between the sum of an electron and a proton versus the mass of a hydrogen atom. George |
#37
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"Pioneer anomalous acceleration" and Cassini
In message , George Dishman
writes OK, if you have any lingering doubts, just remember: solar sails work ;-) Not according to Thomas Gold! -- Rabbit arithmetic - 1 plus 1 equals 10 Remove spam and invalid from address to reply. |
#38
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"Pioneer anomalous acceleration" and Cassini
"George Dishman" wrote in message ...
"Jim Greenfield" wrote in message om... "George Dishman" wrote in message ... There is a recoil because momentum is conserved. The energy of a photon is E=hv and the momentum is p=E/c so the same momentum must be imparted to the emitting object but in the opposite direction. Force F=dp/dt and power P is dE/dt so F=P/c. For Pioneer the power is 8W so the force is 2.67*10^-8 N. The mass is about 240kg so the acceleration is 1.10*10^-10 m/s^2 or 1.10*10^-8 cm/s^2 as you will find it stated in Table II in the paper by Anderson et al, or see eqn (33) in section VIII, A. http://www.arxiv.org/abs/gr-qc/0104064 Thanks George. OK, if you have any lingering doubts, just remember: solar sails work ;-) Since I read of laser "tractors" pushing beads, I never doubted that they would (so long as there is a net "push" in one direction) I find the idea of the transfer of matter from atom - electron - photon - "somewhere in the universe" an interesting issue. If we get into SR, it will make the relationship between energy and mass clearer, and move you on to the next set of interesting questions ;-) Now can I have a set of scales sensitive enough to measure the weight difference as a (sealed) battery runs down? That might be tricky, but the Sun loses about 4 million tons per second this way. We still can't measure it though, but we can measure the difference between the sum of an electron and a proton versus the mass of a hydrogen atom. George Off to the shed to design a rocket which collects inter-stellar hydrogen, runs it through a reactor to convert to EMR, and sends (most) of the radiation out the "back". Not much accelleration, but outside the solar system?? Jim |
#39
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"Pioneer anomalous acceleration" and Cassini
In message , Jim
Greenfield writes Off to the shed to design a rocket which collects inter-stellar hydrogen, runs it through a reactor to convert to EMR, and sends (most) of the radiation out the "back". Not much accelleration, but outside the solar system?? A Busssard ramjet, as you may already know. Doesn't work, for all sorts of reasons. -- Rabbit arithmetic - 1 plus 1 equals 10 Remove spam and invalid from address to reply. |
#40
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"Pioneer anomalous acceleration" and Cassini
In article ,
Jonathan Silverlight writes: A Busssard ramjet, as you may already know. Doesn't work, for all sorts of reasons. Hard to build, no doubt, but "doesn't work?" Why not? Are you thinking of the mythical "ramjet speed limit?" -- Steve Willner Phone 617-495-7123 Cambridge, MA 02138 USA (Please email your reply if you want to be sure I see it; include a valid Reply-To address to receive an acknowledgement. Commercial email may be sent to your ISP.) |
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