Good question. It’s very hard to proof physical things on the blockchain. The term is called oracles. You can reward validators to tell the truth. For example, if you want to bet on a football game, the result of the game needs to be put on the blockchain were everyone agrees that the result is right. It’s a hard problem.
But for crypto payments it’s easier, because you could use a decentralized stable coin or something. Otherwise you need to trust that the stable coin is backed by money. It’s a bit like the same problem of dollars being backed by real gold. You always need some level of trust
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Greetings 
Your questions are not noobs questions. 
They are questions that people that are years in cryptography and busines with programming still try to solve. Also don’t forget that blockchain came out 11 years ago and is still an evolving ecosystem in programming and computers. Nakamoto gave us the “first linux version” of blockchain and we have to bring out the best version that is possible and fair enough for buyers and sellers(or givers and takers). For the charity one good evolution is the binance corona charity in which you have the transparency who gives and who takes but to be actually transparent you need a type of KYC rules and this is something that blockchain and cryptography wants to avoid, because it should be open source. So one big problem is make personal authentications which will stay private on an open source program. That the goals are beeing reached is easy through smart contracts which will say to the blockchain if “this goal is reached” then “reliese the money or the product” to the customer. (more about this on programming section) Also in agricultual and logistic we have solved until now the problem that the seller will not lose his money, but not that the buyer can be sure that he will get his product. This has come up later as a problem which has to be solved and some blockchains try to do, also one good way may be smart contracts that release your money to the seller only if he scans the barcode from the product that he is sending at the time he gives it to the delivery section. Two of my favourite quotes in combination “one makes the start others follow” plus “the student becomes better than the teacher” . Stay safe 
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hi once more. 
I agree with you partly about that the course is a litle short but don’t forget that there are more courses about ethereum and the point of 101 courses is to understand the simple basics, take a taste on what ethereum is and believe me many people don’t even know for example what an erc20 token is, although they may already have one. Also the questions you have set are questions that where not active when this course was made, they came up later and schould be answered from the ethereum comunity and programmers first and they can’t answer them 100% accurate because they are still in a testing point. For example scalability is one problem and can be solved maybe through POS , but no one thought about it when the ethereum came out because no one could have thought that so many users will adopt this system and more are comming. But without testing something which didn’t exist you can’t be sure you have the perfect product for everything. It’s up to us, as people to evolve the systems and our selves 
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Hi Ivan, do ethereum contracts have to be open or can they be hidden from those not authorised to read them?
thanks Ethereum for expanding the use of Blockchain!!!
Having a hard time grasping why the accounting model used by ethereum Is not as private as the UTXO model…
In bitcoin when change is reverted back to the senders wallet . why is that wallet address not the same as the original address that send the money? if that money is going back to the orginal sender??
On ethereum If you cant tell the owner of either of the wallets Why is does this mean its less private?
Thank you!
I will try to explain it quite simple to see if you can understand it better
The UTXO model work with inputs and outputs, inputs for those incoming/received transactions transferred to your wallet, outputs/sent transactions are those payouts you made to another wallet.
When you receive an input lets say 0.5 btc, its received to 1 wallet that you control, now lets say you want to send 0.2 btc to pay something that you buy, you will generate an output of 0.2 btc, but there is 1 input of 0.5 btc, so in order to be able to send only 0.2 btc, you will have to payback yourself the remaining amount(0.3 btc), for that reason, the UTXO model will generate 2 outputs: 1 to the wallet your about to pay for the item you bough and 1 back to you as the remaining (0.3 btc) of the Input that your using (usually that remaining is send to a new fresh wallet that you control too) . This process make a little harder to track the provenance of the funds (but not impossible) from one wallet to another, for that reason you can think that bitcoin UTXO model does offer a “layer” of privacy to any transaction.
You can not payback to the same wallet that your using to send the funds, but off course you can send the funds from 1 wallet/account that you control, to another one of your own control.
The Account model is less private than UTXO because you can track “from, to, quantity, hash, time” on the blockchain in a way more simple than UTXO.
Hope this gives you a clear view of the subject, keep learning! 
If you have any doubt, please let us know so we can help you!
Carlos Z.
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Thank you @Fabrice and @AlexParas for your answers. It feels amazing to receive such consistent replies 
The reason why I asked this specific question is because I am currently working on a school project. With my team I have to develop a (fictitious) business from scratch in the e-commerce sector. So here’s the thing : we want to be an intermediary between local Belgian web shops and local Belgian charities and promote “free donations”. When a consumer buys a product / service on a platform, a reasonable percentage is automatically taken from the total amount and the user sends it to his/her favorite charity. 80% of the amount goes to charity and 20% to keep the business running. So people don’t have to create a wallet and send tokens since we are still at an early adoption stage in crypto. At the end of the day, the consumer doesn’t have to spend an extra euro to donate. It is the seller that makes the financial effort. That is when the blockchain solution comes in. The donation is locked in a smart contract vault until the charity has reached its goal. Then the money is released and the consumer can see the transactions on a dedicated blockchain.
So it may look good (or not) on the paper, but I’m still struggling with the technical part. First for the tokenization part. I know Alice.si uses Tramonex Labs services (a UK fintech startup developed within the Financial Conduct Authority) to do that. Are there any equivalent in Belgium ?
Then the blockchain part. How to evaluate if a charity is trustworthy ? Aidcoin.com created a blockchain (and a token) to broadcast donations. How charities can prove their integrity through blockchain solutions ? And also how businesses such as Aidcoin actually make money ?
My questions go completely Brrrrrrrrrrrrrrr but so is the fog which I can’t escape from. Thanks a lot if your read until the end 
Cheers
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No intro video, just the link to get you going
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Same. Just this link for discussion.
Perhaps will make sense later.
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hi @kyliezz and @Cryptojunkie the first step is introduction to the discussion forum about Eth. Not every intro has a video and the second lesson actually is the intro to the topic.
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Yes I totally get that
Thank you
Yes, yes, I follow. Thank you!
In regards to UTXO concept having more anonymity that the account concept…
Couldn’t you just program a UTXO concept in a smart contract? couldn’t you write a smart contract to pay multiple wallets. is it because the smart contract is just made up of different single transactions, and mainly what is holding Ethereum back is not being able to send " change " in one transaction?
I am just struggling to understand the traceability because at the same time, a single bitcoin can be traced back and you could see exactly that bitcoin comes from, isn’t that saying bitcoin or UTXO concept has LESS anonymity?
@ivan in the Eth description on the first page of the course there is one small spelling error.
This course is perfect for someone who is new to blockchain and is looking to lean(it should be learn) the basics of one of the fastest growing blockchain ecosystems in the world. After this course, you could move on to one of our many programming courses where you can learn how to program smart contracts on Ethereum.
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Thank you sir, will be fixed ASAP. 
Carlos Z.
I’m still a bit confused why BTC contains more privacy than ETH. On the ETH network it’s always clear who sends and who receives. In BTC you could in principle send an amount to somebody and another back to the sender, in the same TX and it’s apprantly not clear who’s who. But why is that? Are the addresses somehow differently interpreted of the recipients on a BTC network TX than on an ETH network TX?
Hello sir, you might want to check this answer that i made for another student days ago, if you still have some doubts on the subject, please feel free to reply here so we can help you to understand it even further!
Ethereum/BTC/Account Model/UTXO.
Hope this gives you a clear view of the subject, keep learning!
If you have any doubt, please let us know so we can help you!
Carlos Z.
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With no introduction information and starting from zero, I’ll come back later to “discuss” when I have some ideas to ask about.
Cheers
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